litmus-rt.git - The LITMUS^RT kernel.

diff options

Diffstat (limited to 'drivers/usb/host/xhci-hcd.c')

-rw-r--r--

125

1 files changed, 125 insertions, 0 deletions


diff --git a/drivers/usb/host/xhci-hcd.c b/drivers/usb/host/xhci-hcd.c index 17f1caf2af64..c8573f874ec4 100644 --- a/drivers/usb/host/xhci-hcd.c +++ b/drivers/usb/host/xhci-hcd.c
@@ -1443,6 +1443,131 @@ void xhci_endpoint_reset(struct usb_hcd *hcd,
1443	}	1443	}
1444		1444
1445	/*	1445	/*
		1446	* This submits a Reset Device Command, which will set the device state to 0,
		1447	* set the device address to 0, and disable all the endpoints except the default
		1448	* control endpoint. The USB core should come back and call
		1449	* xhci_address_device(), and then re-set up the configuration. If this is
		1450	* called because of a usb_reset_and_verify_device(), then the old alternate
		1451	* settings will be re-installed through the normal bandwidth allocation
		1452	* functions.
		1453	*
		1454	* Wait for the Reset Device command to finish. Remove all structures
		1455	* associated with the endpoints that were disabled. Clear the input device
		1456	* structure? Cache the rings? Reset the control endpoint 0 max packet size?
		1457	*/
		1458	int xhci_reset_device(struct usb_hcd hcd, struct usb_device udev)
		1459	{
		1460	int ret, i;
		1461	unsigned long flags;
		1462	struct xhci_hcd *xhci;
		1463	unsigned int slot_id;
		1464	struct xhci_virt_device *virt_dev;
		1465	struct xhci_command *reset_device_cmd;
		1466	int timeleft;
		1467	int last_freed_endpoint;
		1468
		1469	ret = xhci_check_args(hcd, udev, NULL, 0, __func__);
		1470	if (ret <= 0)
		1471	return ret;
		1472	xhci = hcd_to_xhci(hcd);
		1473	slot_id = udev->slot_id;
		1474	virt_dev = xhci->devs[slot_id];
		1475	if (!virt_dev) {
		1476	xhci_dbg(xhci, "%s called with invalid slot ID %u\n",
		1477	__func__, slot_id);
		1478	return -EINVAL;
		1479	}
		1480
		1481	xhci_dbg(xhci, "Resetting device with slot ID %u\n", slot_id);
		1482	/* Allocate the command structure that holds the struct completion.
		1483	* Assume we're in process context, since the normal device reset
		1484	* process has to wait for the device anyway. Storage devices are
		1485	* reset as part of error handling, so use GFP_NOIO instead of
		1486	* GFP_KERNEL.
		1487	*/
		1488	reset_device_cmd = xhci_alloc_command(xhci, false, true, GFP_NOIO);
		1489	if (!reset_device_cmd) {
		1490	xhci_dbg(xhci, "Couldn't allocate command structure.\n");
		1491	return -ENOMEM;
		1492	}
		1493
		1494	/* Attempt to submit the Reset Device command to the command ring */
		1495	spin_lock_irqsave(&xhci->lock, flags);
		1496	reset_device_cmd->command_trb = xhci->cmd_ring->enqueue;
		1497	list_add_tail(&reset_device_cmd->cmd_list, &virt_dev->cmd_list);
		1498	ret = xhci_queue_reset_device(xhci, slot_id);
		1499	if (ret) {
		1500	xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
		1501	list_del(&reset_device_cmd->cmd_list);
		1502	spin_unlock_irqrestore(&xhci->lock, flags);
		1503	goto command_cleanup;
		1504	}
		1505	xhci_ring_cmd_db(xhci);
		1506	spin_unlock_irqrestore(&xhci->lock, flags);
		1507
		1508	/* Wait for the Reset Device command to finish */
		1509	timeleft = wait_for_completion_interruptible_timeout(
		1510	reset_device_cmd->completion,
		1511	USB_CTRL_SET_TIMEOUT);
		1512	if (timeleft <= 0) {
		1513	xhci_warn(xhci, "%s while waiting for reset device command\n",
		1514	timeleft == 0 ? "Timeout" : "Signal");
		1515	spin_lock_irqsave(&xhci->lock, flags);
		1516	/* The timeout might have raced with the event ring handler, so
		1517	* only delete from the list if the item isn't poisoned.
		1518	*/
		1519	if (reset_device_cmd->cmd_list.next != LIST_POISON1)
		1520	list_del(&reset_device_cmd->cmd_list);
		1521	spin_unlock_irqrestore(&xhci->lock, flags);
		1522	ret = -ETIME;
		1523	goto command_cleanup;
		1524	}
		1525
		1526	/* The Reset Device command can't fail, according to the 0.95/0.96 spec,
		1527	* unless we tried to reset a slot ID that wasn't enabled,
		1528	* or the device wasn't in the addressed or configured state.
		1529	*/
		1530	ret = reset_device_cmd->status;
		1531	switch (ret) {
		1532	case COMP_EBADSLT: /* 0.95 completion code for bad slot ID */
		1533	case COMP_CTX_STATE: /* 0.96 completion code for same thing */
		1534	xhci_info(xhci, "Can't reset device (slot ID %u) in %s state\n",
		1535	slot_id,
		1536	xhci_get_slot_state(xhci, virt_dev->out_ctx));
		1537	xhci_info(xhci, "Not freeing device rings.\n");
		1538	/* Don't treat this as an error. May change my mind later. */
		1539	ret = 0;
		1540	goto command_cleanup;
		1541	case COMP_SUCCESS:
		1542	xhci_dbg(xhci, "Successful reset device command.\n");
		1543	break;
		1544	default:
		1545	if (xhci_is_vendor_info_code(xhci, ret))
		1546	break;
		1547	xhci_warn(xhci, "Unknown completion code %u for "
		1548	"reset device command.\n", ret);
		1549	ret = -EINVAL;
		1550	goto command_cleanup;
		1551	}
		1552
		1553	/* Everything but endpoint 0 is disabled, so free or cache the rings. */
		1554	last_freed_endpoint = 1;
		1555	for (i = 1; i < 31; ++i) {
		1556	if (!virt_dev->eps[i].ring)
		1557	continue;
		1558	xhci_free_or_cache_endpoint_ring(xhci, virt_dev, i);
		1559	last_freed_endpoint = i;
		1560	}
		1561	xhci_dbg(xhci, "Output context after successful reset device cmd:\n");
		1562	xhci_dbg_ctx(xhci, virt_dev->out_ctx, last_freed_endpoint);
		1563	ret = 0;
		1564
		1565	command_cleanup:
		1566	xhci_free_command(xhci, reset_device_cmd);
		1567	return ret;
		1568	}
		1569
		1570	/*
1446	* At this point, the struct usb_device is about to go away, the device has	1571	* At this point, the struct usb_device is about to go away, the device has
1447	* disconnected, and all traffic has been stopped and the endpoints have been	1572	* disconnected, and all traffic has been stopped and the endpoints have been
1448	* disabled. Free any HC data structures associated with that device.	1573	* disabled. Free any HC data structures associated with that device.

/* * linux/drivers/char/tty_io.c * * Copyright (C) 1991, 1992 Linus Torvalds */ /* * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles * or rs-channels. It also implements echoing, cooked mode etc. * * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0. * * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the * tty_struct and tty_queue structures. Previously there was an array * of 256 tty_struct's which was statically allocated, and the * tty_queue structures were allocated at boot time. Both are now * dynamically allocated only when the tty is open. * * Also restructured routines so that there is more of a separation * between the high-level tty routines (tty_io.c and tty_ioctl.c) and * the low-level tty routines (serial.c, pty.c, console.c). This * makes for cleaner and more compact code. -TYT, 9/17/92 * * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines * which can be dynamically activated and de-activated by the line * discipline handling modules (like SLIP). * * NOTE: pay no attention to the line discipline code (yet); its * interface is still subject to change in this version... * -- TYT, 1/31/92 * * Added functionality to the OPOST tty handling. No delays, but all * other bits should be there. * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993. * * Rewrote canonical mode and added more termios flags. * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94 * * Reorganized FASYNC support so mouse code can share it. * -- ctm@ardi.com, 9Sep95 * * New TIOCLINUX variants added. * -- mj@k332.feld.cvut.cz, 19-Nov-95 * * Restrict vt switching via ioctl() * -- grif@cs.ucr.edu, 5-Dec-95 * * Move console and virtual terminal code to more appropriate files, * implement CONFIG_VT and generalize console device interface. * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97 * * Rewrote init_dev and release_dev to eliminate races. * -- Bill Hawes <whawes@star.net>, June 97 * * Added devfs support. * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998 * * Added support for a Unix98-style ptmx device. * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998 * * Reduced memory usage for older ARM systems * -- Russell King <rmk@arm.linux.org.uk> * * Move do_SAK() into process context. Less stack use in devfs functions. * alloc_tty_struct() always uses kmalloc() * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01 */ #include <linux/types.h> #include <linux/major.h> #include <linux/errno.h> #include <linux/signal.h> #include <linux/fcntl.h> #include <linux/sched.h> #include <linux/interrupt.h> #include <linux/tty.h> #include <linux/tty_driver.h> #include <linux/tty_flip.h> #include <linux/devpts_fs.h> #include <linux/file.h> #include <linux/console.h> #include <linux/timer.h> #include <linux/ctype.h> #include <linux/kd.h> #include <linux/mm.h> #include <linux/string.h> #include <linux/slab.h> #include <linux/poll.h> #include <linux/proc_fs.h> #include <linux/init.h> #include <linux/module.h> #include <linux/smp_lock.h> #include <linux/device.h> #include <linux/idr.h> #include <linux/wait.h> #include <linux/bitops.h> #include <linux/delay.h> #include <asm/uaccess.h> #include <asm/system.h> #include <linux/kbd_kern.h> #include <linux/vt_kern.h> #include <linux/selection.h> #include <linux/kmod.h> #include <linux/nsproxy.h> #undef TTY_DEBUG_HANGUP #define TTY_PARANOIA_CHECK 1 #define CHECK_TTY_COUNT 1 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */ .c_iflag = ICRNL | IXON, .c_oflag = OPOST | ONLCR, .c_cflag = B38400 | CS8 | CREAD | HUPCL, .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN, .c_cc = INIT_C_CC, .c_ispeed = 38400, .c_ospeed = 38400 }; EXPORT_SYMBOL(tty_std_termios); /* This list gets poked at by procfs and various bits of boot up code. This could do with some rationalisation such as pulling the tty proc function into this file */ LIST_HEAD(tty_drivers); /* linked list of tty drivers */ /* Mutex to protect creating and releasing a tty. This is shared with vt.c for deeply disgusting hack reasons */ DEFINE_MUTEX(tty_mutex); EXPORT_SYMBOL(tty_mutex); #ifdef CONFIG_UNIX98_PTYS extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */ extern int pty_limit; /* Config limit on Unix98 ptys */ static DEFINE_IDR(allocated_ptys); static DEFINE_MUTEX(allocated_ptys_lock); static int ptmx_open(struct inode *, struct file *); #endif static void initialize_tty_struct(struct tty_struct *tty); static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *); static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *); ssize_t redirected_tty_write(struct file *, const char __user *, size_t, loff_t *); static unsigned int tty_poll(struct file *, poll_table *); static int tty_open(struct inode *, struct file *); static int tty_release(struct inode *, struct file *); int tty_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg); #ifdef CONFIG_COMPAT static long tty_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg); #else #define tty_compat_ioctl NULL #endif static int tty_fasync(int fd, struct file *filp, int on); static void release_tty(struct tty_struct *tty, int idx); static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty); static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty); /** * alloc_tty_struct - allocate a tty object * * Return a new empty tty structure. The data fields have not * been initialized in any way but has been zeroed * * Locking: none */ static struct tty_struct *alloc_tty_struct(void) { return kzalloc(sizeof(struct tty_struct), GFP_KERNEL); } static void tty_buffer_free_all(struct tty_struct *); /** * free_tty_struct - free a disused tty * @tty: tty struct to free * * Free the write buffers, tty queue and tty memory itself. * * Locking: none. Must be called after tty is definitely unused */ static inline void free_tty_struct(struct tty_struct *tty) { kfree(tty->write_buf); tty_buffer_free_all(tty); kfree(tty); } #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base) /** * tty_name - return tty naming * @tty: tty structure * @buf: buffer for output * * Convert a tty structure into a name. The name reflects the kernel * naming policy and if udev is in use may not reflect user space * * Locking: none */ char *tty_name(struct tty_struct *tty, char *buf) { if (!tty) /* Hmm. NULL pointer. That's fun. */ strcpy(buf, "NULL tty"); else strcpy(buf, tty->name); return buf; } EXPORT_SYMBOL(tty_name); int tty_paranoia_check(struct tty_struct *tty, struct inode *inode, const char *routine) { #ifdef TTY_PARANOIA_CHECK if (!tty) { printk(KERN_WARNING "null TTY for (%d:%d) in %s\n", imajor(inode), iminor(inode), routine); return 1; } if (tty->magic != TTY_MAGIC) { printk(KERN_WARNING "bad magic number for tty struct (%d:%d) in %s\n", imajor(inode), iminor(inode), routine); return 1; } #endif return 0; } static int check_tty_count(struct tty_struct *tty, const char *routine) { #ifdef CHECK_TTY_COUNT struct list_head *p; int count = 0; file_list_lock(); list_for_each(p, &tty->tty_files) { count++; } file_list_unlock(); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_SLAVE && tty->link && tty->link->count) count++; if (tty->count != count) { printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) " "!= #fd's(%d) in %s\n", tty->name, tty->count, count, routine); return count; } #endif return 0; } /* * Tty buffer allocation management */ /** * tty_buffer_free_all - free buffers used by a tty * @tty: tty to free from * * Remove all the buffers pending on a tty whether queued with data * or in the free ring. Must be called when the tty is no longer in use * * Locking: none */ static void tty_buffer_free_all(struct tty_struct *tty) { struct tty_buffer *thead; while ((thead = tty->buf.head) != NULL) { tty->buf.head = thead->next; kfree(thead); } while ((thead = tty->buf.free) != NULL) { tty->buf.free = thead->next; kfree(thead); } tty->buf.tail = NULL; tty->buf.memory_used = 0; } /** * tty_buffer_init - prepare a tty buffer structure * @tty: tty to initialise * * Set up the initial state of the buffer management for a tty device. * Must be called before the other tty buffer functions are used. * * Locking: none */ static void tty_buffer_init(struct tty_struct *tty) { spin_lock_init(&tty->buf.lock); tty->buf.head = NULL; tty->buf.tail = NULL; tty->buf.free = NULL; tty->buf.memory_used = 0; } /** * tty_buffer_alloc - allocate a tty buffer * @tty: tty device * @size: desired size (characters) * * Allocate a new tty buffer to hold the desired number of characters. * Return NULL if out of memory or the allocation would exceed the * per device queue * * Locking: Caller must hold tty->buf.lock */ static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size) { struct tty_buffer *p; if (tty->buf.memory_used + size > 65536) return NULL; p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); if (p == NULL) return NULL; p->used = 0; p->size = size; p->next = NULL; p->commit = 0; p->read = 0; p->char_buf_ptr = (char *)(p->data); p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size; tty->buf.memory_used += size; return p; } /** * tty_buffer_free - free a tty buffer * @tty: tty owning the buffer * @b: the buffer to free * * Free a tty buffer, or add it to the free list according to our * internal strategy * * Locking: Caller must hold tty->buf.lock */ static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b) { /* Dumb strategy for now - should keep some stats */ tty->buf.memory_used -= b->size; WARN_ON(tty->buf.memory_used < 0); if (b->size >= 512) kfree(b); else { b->next = tty->buf.free; tty->buf.free = b; } } /** * __tty_buffer_flush - flush full tty buffers * @tty: tty to flush * * flush all the buffers containing receive data. Caller must * hold the buffer lock and must have ensured no parallel flush to * ldisc is running. * * Locking: Caller must hold tty->buf.lock */ static void __tty_buffer_flush(struct tty_struct *tty) { struct tty_buffer *thead; while ((thead = tty->buf.head) != NULL) { tty->buf.head = thead->next; tty_buffer_free(tty, thead); } tty->buf.tail = NULL; } /** * tty_buffer_flush - flush full tty buffers * @tty: tty to flush * * flush all the buffers containing receive data. If the buffer is * being processed by flush_to_ldisc then we defer the processing * to that function * * Locking: none */ static void tty_buffer_flush(struct tty_struct *tty) { unsigned long flags; spin_lock_irqsave(&tty->buf.lock, flags); /* If the data is being pushed to the tty layer then we can't process it here. Instead set a flag and the flush_to_ldisc path will process the flush request before it exits */ if (test_bit(TTY_FLUSHING, &tty->flags)) { set_bit(TTY_FLUSHPENDING, &tty->flags); spin_unlock_irqrestore(&tty->buf.lock, flags); wait_event(tty->read_wait, test_bit(TTY_FLUSHPENDING, &tty->flags) == 0); return; } else __tty_buffer_flush(tty); spin_unlock_irqrestore(&tty->buf.lock, flags); } /** * tty_buffer_find - find a free tty buffer * @tty: tty owning the buffer * @size: characters wanted * * Locate an existing suitable tty buffer or if we are lacking one then * allocate a new one. We round our buffers off in 256 character chunks * to get better allocation behaviour. * * Locking: Caller must hold tty->buf.lock */ static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size) { struct tty_buffer **tbh = &tty->buf.free; while ((*tbh) != NULL) { struct tty_buffer *t = *tbh; if (t->size >= size) { *tbh = t->next; t->next = NULL; t->used = 0; t->commit = 0; t->read = 0; tty->buf.memory_used += t->size; return t; } tbh = &((*tbh)->next); } /* Round the buffer size out */ size = (size + 0xFF) & ~0xFF; return tty_buffer_alloc(tty, size); /* Should possibly check if this fails for the largest buffer we have queued and recycle that ? */ } /** * tty_buffer_request_room - grow tty buffer if needed * @tty: tty structure * @size: size desired * * Make at least size bytes of linear space available for the tty * buffer. If we fail return the size we managed to find. * * Locking: Takes tty->buf.lock */ int tty_buffer_request_room(struct tty_struct *tty, size_t size) { struct tty_buffer *b, *n; int left; unsigned long flags; spin_lock_irqsave(&tty->buf.lock, flags); /* OPTIMISATION: We could keep a per tty "zero" sized buffer to remove this conditional if its worth it. This would be invisible to the callers */ if ((b = tty->buf.tail) != NULL) left = b->size - b->used; else left = 0; if (left < size) { /* This is the slow path - looking for new buffers to use */ if ((n = tty_buffer_find(tty, size)) != NULL) { if (b != NULL) { b->next = n; b->commit = b->used; } else tty->buf.head = n; tty->buf.tail = n; } else size = left; } spin_unlock_irqrestore(&tty->buf.lock, flags); return size; } EXPORT_SYMBOL_GPL(tty_buffer_request_room); /** * tty_insert_flip_string - Add characters to the tty buffer * @tty: tty structure * @chars: characters * @size: size * * Queue a series of bytes to the tty buffering. All the characters * passed are marked as without error. Returns the number added. * * Locking: Called functions may take tty->buf.lock */ int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars, size_t size) { int copied = 0; do { int space = tty_buffer_request_room(tty, size - copied); struct tty_buffer *tb = tty->buf.tail; /* If there is no space then tb may be NULL */ if (unlikely(space == 0)) break; memcpy(tb->char_buf_ptr + tb->used, chars, space); memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space); tb->used += space; copied += space; chars += space; /* There is a small chance that we need to split the data over several buffers. If this is the case we must loop */ } while (unlikely(size > copied)); return copied; } EXPORT_SYMBOL(tty_insert_flip_string); /** * tty_insert_flip_string_flags - Add characters to the tty buffer * @tty: tty structure * @chars: characters * @flags: flag bytes * @size: size * * Queue a series of bytes to the tty buffering. For each character * the flags array indicates the status of the character. Returns the * number added. * * Locking: Called functions may take tty->buf.lock */ int tty_insert_flip_string_flags(struct tty_struct *tty, const unsigned char *chars, const char *flags, size_t size) { int copied = 0; do { int space = tty_buffer_request_room(tty, size - copied); struct tty_buffer *tb = tty->buf.tail; /* If there is no space then tb may be NULL */ if (unlikely(space == 0)) break; memcpy(tb->char_buf_ptr + tb->used, chars, space); memcpy(tb->flag_buf_ptr + tb->used, flags, space); tb->used += space; copied += space; chars += space; flags += space; /* There is a small chance that we need to split the data over several buffers. If this is the case we must loop */ } while (unlikely(size > copied)); return copied; } EXPORT_SYMBOL(tty_insert_flip_string_flags); /** * tty_schedule_flip - push characters to ldisc * @tty: tty to push from * * Takes any pending buffers and transfers their ownership to the * ldisc side of the queue. It then schedules those characters for * processing by the line discipline. * * Locking: Takes tty->buf.lock */ void tty_schedule_flip(struct tty_struct *tty) { unsigned long flags; spin_lock_irqsave(&tty->buf.lock, flags); if (tty->buf.tail != NULL) tty->buf.tail->commit = tty->buf.tail->used; spin_unlock_irqrestore(&tty->buf.lock, flags); schedule_delayed_work(&tty->buf.work, 1); } EXPORT_SYMBOL(tty_schedule_flip); /** * tty_prepare_flip_string - make room for characters * @tty: tty * @chars: return pointer for character write area * @size: desired size * * Prepare a block of space in the buffer for data. Returns the length * available and buffer pointer to the space which is now allocated and * accounted for as ready for normal characters. This is used for drivers * that need their own block copy routines into the buffer. There is no * guarantee the buffer is a DMA target! * * Locking: May call functions taking tty->buf.lock */ int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size) { int space = tty_buffer_request_room(tty, size); if (likely(space)) { struct tty_buffer *tb = tty->buf.tail; *chars = tb->char_buf_ptr + tb->used; memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space); tb->used += space; } return space; } EXPORT_SYMBOL_GPL(tty_prepare_flip_string); /** * tty_prepare_flip_string_flags - make room for characters * @tty: tty * @chars: return pointer for character write area * @flags: return pointer for status flag write area * @size: desired size * * Prepare a block of space in the buffer for data. Returns the length * available and buffer pointer to the space which is now allocated and * accounted for as ready for characters. This is used for drivers * that need their own block copy routines into the buffer. There is no * guarantee the buffer is a DMA target! * * Locking: May call functions taking tty->buf.lock */ int tty_prepare_flip_string_flags(struct tty_struct *tty, unsigned char **chars, char **flags, size_t size) { int space = tty_buffer_request_room(tty, size); if (likely(space)) { struct tty_buffer *tb = tty->buf.tail; *chars = tb->char_buf_ptr + tb->used; *flags = tb->flag_buf_ptr + tb->used; tb->used += space; } return space; } EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); /** * tty_set_termios_ldisc - set ldisc field * @tty: tty structure * @num: line discipline number * * This is probably overkill for real world processors but * they are not on hot paths so a little discipline won't do * any harm. * * Locking: takes termios_mutex */ static void tty_set_termios_ldisc(struct tty_struct *tty, int num) { mutex_lock(&tty->termios_mutex); tty->termios->c_line = num; mutex_unlock(&tty->termios_mutex); } /* * This guards the refcounted line discipline lists. The lock * must be taken with irqs off because there are hangup path * callers who will do ldisc lookups and cannot sleep. */ static DEFINE_SPINLOCK(tty_ldisc_lock); static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait); /* Line disc dispatch table */ static struct tty_ldisc tty_ldiscs[NR_LDISCS]; /** * tty_register_ldisc - install a line discipline * @disc: ldisc number * @new_ldisc: pointer to the ldisc object * * Installs a new line discipline into the kernel. The discipline * is set up as unreferenced and then made available to the kernel * from this point onwards. * * Locking: * takes tty_ldisc_lock to guard against ldisc races */ int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc) { unsigned long flags; int ret = 0; if (disc < N_TTY || disc >= NR_LDISCS) return -EINVAL; spin_lock_irqsave(&tty_ldisc_lock, flags); tty_ldiscs[disc] = *new_ldisc; tty_ldiscs[disc].num = disc; tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED; tty_ldiscs[disc].refcount = 0; spin_unlock_irqrestore(&tty_ldisc_lock, flags); return ret; } EXPORT_SYMBOL(tty_register_ldisc); /** * tty_unregister_ldisc - unload a line discipline * @disc: ldisc number * @new_ldisc: pointer to the ldisc object * * Remove a line discipline from the kernel providing it is not * currently in use. * * Locking: * takes tty_ldisc_lock to guard against ldisc races */ int tty_unregister_ldisc(int disc) { unsigned long flags; int ret = 0; if (disc < N_TTY || disc >= NR_LDISCS) return -EINVAL; spin_lock_irqsave(&tty_ldisc_lock, flags); if (tty_ldiscs[disc].refcount) ret = -EBUSY; else tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED; spin_unlock_irqrestore(&tty_ldisc_lock, flags); return ret; } EXPORT_SYMBOL(tty_unregister_ldisc); /** * tty_ldisc_get - take a reference to an ldisc * @disc: ldisc number * * Takes a reference to a line discipline. Deals with refcounts and * module locking counts. Returns NULL if the discipline is not available. * Returns a pointer to the discipline and bumps the ref count if it is * available * * Locking: * takes tty_ldisc_lock to guard against ldisc races */ struct tty_ldisc *tty_ldisc_get(int disc) { unsigned long flags; struct tty_ldisc *ld; if (disc < N_TTY || disc >= NR_LDISCS) return NULL; spin_lock_irqsave(&tty_ldisc_lock, flags); ld = &tty_ldiscs[disc]; /* Check the entry is defined */ if (ld->flags & LDISC_FLAG_DEFINED) { /* If the module is being unloaded we can't use it */ if (!try_module_get(ld->owner)) ld = NULL; else /* lock it */ ld->refcount++; } else ld = NULL; spin_unlock_irqrestore(&tty_ldisc_lock, flags); return ld; } EXPORT_SYMBOL_GPL(tty_ldisc_get); /** * tty_ldisc_put - drop ldisc reference * @disc: ldisc number * * Drop a reference to a line discipline. Manage refcounts and * module usage counts * * Locking: * takes tty_ldisc_lock to guard against ldisc races */ void tty_ldisc_put(int disc) { struct tty_ldisc *ld; unsigned long flags; BUG_ON(disc < N_TTY || disc >= NR_LDISCS); spin_lock_irqsave(&tty_ldisc_lock, flags); ld = &tty_ldiscs[disc]; BUG_ON(ld->refcount == 0); ld->refcount--; module_put(ld->owner); spin_unlock_irqrestore(&tty_ldisc_lock, flags); } EXPORT_SYMBOL_GPL(tty_ldisc_put); /** * tty_ldisc_assign - set ldisc on a tty * @tty: tty to assign * @ld: line discipline * * Install an instance of a line discipline into a tty structure. The * ldisc must have a reference count above zero to ensure it remains/ * The tty instance refcount starts at zero. * * Locking: * Caller must hold references */ static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld) { tty->ldisc = *ld; tty->ldisc.refcount = 0; } /** * tty_ldisc_try - internal helper * @tty: the tty * * Make a single attempt to grab and bump the refcount on * the tty ldisc. Return 0 on failure or 1 on success. This is * used to implement both the waiting and non waiting versions * of tty_ldisc_ref * * Locking: takes tty_ldisc_lock */ static int tty_ldisc_try(struct tty_struct *tty) { unsigned long flags; struct tty_ldisc *ld; int ret = 0; spin_lock_irqsave(&tty_ldisc_lock, flags); ld = &tty->ldisc; if (test_bit(TTY_LDISC, &tty->flags)) { ld->refcount++; ret = 1; } spin_unlock_irqrestore(&tty_ldisc_lock, flags); return ret; } /** * tty_ldisc_ref_wait - wait for the tty ldisc * @tty: tty device * * Dereference the line discipline for the terminal and take a * reference to it. If the line discipline is in flux then * wait patiently until it changes. * * Note: Must not be called from an IRQ/timer context. The caller * must also be careful not to hold other locks that will deadlock * against a discipline change, such as an existing ldisc reference * (which we check for) * * Locking: call functions take tty_ldisc_lock */ struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) { /* wait_event is a macro */ wait_event(tty_ldisc_wait, tty_ldisc_try(tty)); if (tty->ldisc.refcount == 0) printk(KERN_ERR "tty_ldisc_ref_wait\n"); return &tty->ldisc; } EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); /** * tty_ldisc_ref - get the tty ldisc * @tty: tty device * * Dereference the line discipline for the terminal and take a * reference to it. If the line discipline is in flux then * return NULL. Can be called from IRQ and timer functions. * * Locking: called functions take tty_ldisc_lock */ struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) { if (tty_ldisc_try(tty)) return &tty->ldisc; return NULL; } EXPORT_SYMBOL_GPL(tty_ldisc_ref); /** * tty_ldisc_deref - free a tty ldisc reference * @ld: reference to free up * * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May * be called in IRQ context. * * Locking: takes tty_ldisc_lock */ void tty_ldisc_deref(struct tty_ldisc *ld) { unsigned long flags; BUG_ON(ld == NULL); spin_lock_irqsave(&tty_ldisc_lock, flags); if (ld->refcount == 0) printk(KERN_ERR "tty_ldisc_deref: no references.\n"); else ld->refcount--; if (ld->refcount == 0) wake_up(&tty_ldisc_wait); spin_unlock_irqrestore(&tty_ldisc_lock, flags); } EXPORT_SYMBOL_GPL(tty_ldisc_deref); /** * tty_ldisc_enable - allow ldisc use * @tty: terminal to activate ldisc on * * Set the TTY_LDISC flag when the line discipline can be called * again. Do necessary wakeups for existing sleepers. * * Note: nobody should set this bit except via this function. Clearing * directly is allowed. */ static void tty_ldisc_enable(struct tty_struct *tty) { set_bit(TTY_LDISC, &tty->flags); wake_up(&tty_ldisc_wait); } /** * tty_set_ldisc - set line discipline * @tty: the terminal to set * @ldisc: the line discipline * * Set the discipline of a tty line. Must be called from a process * context. * * Locking: takes tty_ldisc_lock. * called functions take termios_mutex */ static int tty_set_ldisc(struct tty_struct *tty, int ldisc) { int retval = 0; struct tty_ldisc o_ldisc; char buf[64]; int work; unsigned long flags; struct tty_ldisc *ld; struct tty_struct *o_tty; if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS)) return -EINVAL; restart: ld = tty_ldisc_get(ldisc); /* Eduardo Blanco <ejbs@cs.cs.com.uy> */ /* Cyrus Durgin <cider@speakeasy.org> */ if (ld == NULL) { request_module("tty-ldisc-%d", ldisc); ld = tty_ldisc_get(ldisc); } if (ld == NULL) return -EINVAL; /* * Problem: What do we do if this blocks ? */ tty_wait_until_sent(tty, 0); if (tty->ldisc.num == ldisc) { tty_ldisc_put(ldisc); return 0; } /* * No more input please, we are switching. The new ldisc * will update this value in the ldisc open function */ tty->receive_room = 0; o_ldisc = tty->ldisc; o_tty = tty->link; /* * Make sure we don't change while someone holds a * reference to the line discipline. The TTY_LDISC bit * prevents anyone taking a reference once it is clear. * We need the lock to avoid racing reference takers. */ spin_lock_irqsave(&tty_ldisc_lock, flags); if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) { if (tty->ldisc.refcount) { /* Free the new ldisc we grabbed. Must drop the lock first. */ spin_unlock_irqrestore(&tty_ldisc_lock, flags); tty_ldisc_put(ldisc); /* * There are several reasons we may be busy, including * random momentary I/O traffic. We must therefore * retry. We could distinguish between blocking ops * and retries if we made tty_ldisc_wait() smarter. * That is up for discussion. */ if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0) return -ERESTARTSYS; goto restart; } if (o_tty && o_tty->ldisc.refcount) { spin_unlock_irqrestore(&tty_ldisc_lock, flags); tty_ldisc_put(ldisc); if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0) return -ERESTARTSYS; goto restart; } } /* * If the TTY_LDISC bit is set, then we are racing against * another ldisc change */ if (!test_bit(TTY_LDISC, &tty->flags)) { spin_unlock_irqrestore(&tty_ldisc_lock, flags); tty_ldisc_put(ldisc); ld = tty_ldisc_ref_wait(tty); tty_ldisc_deref(ld); goto restart; } clear_bit(TTY_LDISC, &tty->flags); if (o_tty) clear_bit(TTY_LDISC, &o_tty->flags); spin_unlock_irqrestore(&tty_ldisc_lock, flags); /* * From this point on we know nobody has an ldisc * usage reference, nor can they obtain one until * we say so later on. */ work = cancel_delayed_work(&tty->buf.work); /* * Wait for ->hangup_work and ->buf.work handlers to terminate */ flush_scheduled_work(); /* Shutdown the current discipline. */ if (tty->ldisc.close) (tty->ldisc.close)(tty); /* Now set up the new line discipline. */ tty_ldisc_assign(tty, ld); tty_set_termios_ldisc(tty, ldisc); if (tty->ldisc.open) retval = (tty->ldisc.open)(tty); if (retval < 0) { tty_ldisc_put(ldisc); /* There is an outstanding reference here so this is safe */ tty_ldisc_assign(tty, tty_ldisc_get(o_ldisc.num)); tty_set_termios_ldisc(tty, tty->ldisc.num); if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) { tty_ldisc_put(o_ldisc.num); /* This driver is always present */ tty_ldisc_assign(tty, tty_ldisc_get(N_TTY)); tty_set_termios_ldisc(tty, N_TTY); if (tty->ldisc.open) { int r = tty->ldisc.open(tty); if (r < 0) panic("Couldn't open N_TTY ldisc for " "%s --- error %d.", tty_name(tty, buf), r); } } } /* At this point we hold a reference to the new ldisc and a a reference to the old ldisc. If we ended up flipping back to the existing ldisc we have two references to it */ if (tty->ldisc.num != o_ldisc.num && tty->driver->set_ldisc) tty->driver->set_ldisc(tty); tty_ldisc_put(o_ldisc.num); /* * Allow ldisc referencing to occur as soon as the driver * ldisc callback completes. */ tty_ldisc_enable(tty); if (o_tty) tty_ldisc_enable(o_tty); /* Restart it in case no characters kick it off. Safe if already running */ if (work) schedule_delayed_work(&tty->buf.work, 1); return retval; } /** * get_tty_driver - find device of a tty * @dev_t: device identifier * @index: returns the index of the tty * * This routine returns a tty driver structure, given a device number * and also passes back the index number. * * Locking: caller must hold tty_mutex */ static struct tty_driver *get_tty_driver(dev_t device, int *index) { struct tty_driver *p; list_for_each_entry(p, &tty_drivers, tty_drivers) { dev_t base = MKDEV(p->major, p->minor_start); if (device < base || device >= base + p->num) continue; *index = device - base; return p; } return NULL; } #ifdef CONFIG_CONSOLE_POLL /** * tty_find_polling_driver - find device of a polled tty * @name: name string to match * @line: pointer to resulting tty line nr * * This routine returns a tty driver structure, given a name * and the condition that the tty driver is capable of polled * operation. */ struct tty_driver *tty_find_polling_driver(char *name, int *line) { struct tty_driver *p, *res = NULL; int tty_line = 0; char *str; mutex_lock(&tty_mutex); /* Search through the tty devices to look for a match */ list_for_each_entry(p, &tty_drivers, tty_drivers) { str = name + strlen(p->name); tty_line = simple_strtoul(str, &str, 10); if (*str == ',') str++; if (*str == '\0') str = 0; if (tty_line >= 0 && tty_line <= p->num && p->poll_init && !p->poll_init(p, tty_line, str)) { res = p; *line = tty_line; break; } } mutex_unlock(&tty_mutex); return res; } EXPORT_SYMBOL_GPL(tty_find_polling_driver); #endif /** * tty_check_change - check for POSIX terminal changes * @tty: tty to check * * If we try to write to, or set the state of, a terminal and we're * not in the foreground, send a SIGTTOU. If the signal is blocked or * ignored, go ahead and perform the operation. (POSIX 7.2) * * Locking: none */ int tty_check_change(struct tty_struct *tty) { if (current->signal->tty != tty) return 0; if (!tty->pgrp) { printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n"); return 0; } if (task_pgrp(current) == tty->pgrp) return 0; if (is_ignored(SIGTTOU)) return 0; if (is_current_pgrp_orphaned()) return -EIO; kill_pgrp(task_pgrp(current), SIGTTOU, 1); set_thread_flag(TIF_SIGPENDING); return -ERESTARTSYS; } EXPORT_SYMBOL(tty_check_change); static ssize_t hung_up_tty_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { return 0; } static ssize_t hung_up_tty_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { return -EIO; } /* No kernel lock held - none needed ;) */ static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait) { return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM; } static int hung_up_tty_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg) { return cmd == TIOCSPGRP ? -ENOTTY : -EIO; } static long hung_up_tty_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { return cmd == TIOCSPGRP ? -ENOTTY : -EIO; } static const struct file_operations tty_fops = { .llseek = no_llseek, .read = tty_read, .write = tty_write, .poll = tty_poll, .ioctl = tty_ioctl, .compat_ioctl = tty_compat_ioctl, .open = tty_open, .release = tty_release, .fasync = tty_fasync, }; #ifdef CONFIG_UNIX98_PTYS static const struct file_operations ptmx_fops = { .llseek = no_llseek, .read = tty_read, .write = tty_write, .poll = tty_poll, .ioctl = tty_ioctl, .compat_ioctl = tty_compat_ioctl, .open = ptmx_open, .release = tty_release, .fasync = tty_fasync, }; #endif static const struct file_operations console_fops = { .llseek = no_llseek, .read = tty_read, .write = redirected_tty_write, .poll = tty_poll, .ioctl = tty_ioctl, .compat_ioctl = tty_compat_ioctl, .open = tty_open, .release = tty_release, .fasync = tty_fasync, }; static const struct file_operations hung_up_tty_fops = { .llseek = no_llseek, .read = hung_up_tty_read, .write = hung_up_tty_write, .poll = hung_up_tty_poll, .ioctl = hung_up_tty_ioctl, .compat_ioctl = hung_up_tty_compat_ioctl, .release = tty_release, }; static DEFINE_SPINLOCK(redirect_lock); static struct file *redirect; /** * tty_wakeup - request more data * @tty: terminal * * Internal and external helper for wakeups of tty. This function * informs the line discipline if present that the driver is ready * to receive more output data. */ void tty_wakeup(struct tty_struct *tty) { struct tty_ldisc *ld; if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) { ld = tty_ldisc_ref(tty); if (ld) { if (ld->write_wakeup) ld->write_wakeup(tty); tty_ldisc_deref(ld); } } wake_up_interruptible(&tty->write_wait); } EXPORT_SYMBOL_GPL(tty_wakeup); /** * tty_ldisc_flush - flush line discipline queue * @tty: tty * * Flush the line discipline queue (if any) for this tty. If there * is no line discipline active this is a no-op. */ void tty_ldisc_flush(struct tty_struct *tty) { struct tty_ldisc *ld = tty_ldisc_ref(tty); if (ld) { if (ld->flush_buffer) ld->flush_buffer(tty); tty_ldisc_deref(ld); } tty_buffer_flush(tty); } EXPORT_SYMBOL_GPL(tty_ldisc_flush); /** * tty_reset_termios - reset terminal state * @tty: tty to reset * * Restore a terminal to the driver default state */ static void tty_reset_termios(struct tty_struct *tty) { mutex_lock(&tty->termios_mutex); *tty->termios = tty->driver->init_termios; tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios); tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios); mutex_unlock(&tty->termios_mutex); } /** * do_tty_hangup - actual handler for hangup events * @work: tty device * * This can be called by the "eventd" kernel thread. That is process * synchronous but doesn't hold any locks, so we need to make sure we * have the appropriate locks for what we're doing. * * The hangup event clears any pending redirections onto the hung up * device. It ensures future writes will error and it does the needed * line discipline hangup and signal delivery. The tty object itself * remains intact. * * Locking: * BKL * redirect lock for undoing redirection * file list lock for manipulating list of ttys * tty_ldisc_lock from called functions * termios_mutex resetting termios data * tasklist_lock to walk task list for hangup event * ->siglock to protect ->signal/->sighand */ static void do_tty_hangup(struct work_struct *work) { struct tty_struct *tty = container_of(work, struct tty_struct, hangup_work); struct file *cons_filp = NULL; struct file *filp, *f = NULL; struct task_struct *p; struct tty_ldisc *ld; int closecount = 0, n; if (!tty) return; /* inuse_filps is protected by the single kernel lock */ lock_kernel(); spin_lock(&redirect_lock); if (redirect && redirect->private_data == tty) { f = redirect; redirect = NULL; } spin_unlock(&redirect_lock); check_tty_count(tty, "do_tty_hangup"); file_list_lock(); /* This breaks for file handles being sent over AF_UNIX sockets ? */ list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) { if (filp->f_op->write == redirected_tty_write) cons_filp = filp; if (filp->f_op->write != tty_write) continue; closecount++; tty_fasync(-1, filp, 0); /* can't block */ filp->f_op = &hung_up_tty_fops; } file_list_unlock(); /* * FIXME! What are the locking issues here? This may me overdoing * things... This question is especially important now that we've * removed the irqlock. */ ld = tty_ldisc_ref(tty); if (ld != NULL) { /* We may have no line discipline at this point */ if (ld->flush_buffer) ld->flush_buffer(tty); if (tty->driver->flush_buffer) tty->driver->flush_buffer(tty); if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && ld->write_wakeup) ld->write_wakeup(tty); if (ld->hangup) ld->hangup(tty); } /* * FIXME: Once we trust the LDISC code better we can wait here for * ldisc completion and fix the driver call race */ wake_up_interruptible(&tty->write_wait); wake_up_interruptible(&tty->read_wait); /* * Shutdown the current line discipline, and reset it to * N_TTY. */ if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) tty_reset_termios(tty); /* Defer ldisc switch */ /* tty_deferred_ldisc_switch(N_TTY); This should get done automatically when the port closes and tty_release is called */ read_lock(&tasklist_lock); if (tty->session) { do_each_pid_task(tty->session, PIDTYPE_SID, p) { spin_lock_irq(&p->sighand->siglock); if (p->signal->tty == tty) p->signal->tty = NULL; if (!p->signal->leader) { spin_unlock_irq(&p->sighand->siglock); continue; } __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p); __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p); put_pid(p->signal->tty_old_pgrp); /* A noop */ if (tty->pgrp) p->signal->tty_old_pgrp = get_pid(tty->pgrp); spin_unlock_irq(&p->sighand->siglock); } while_each_pid_task(tty->session, PIDTYPE_SID, p); } read_unlock(&tasklist_lock); tty->flags = 0; put_pid(tty->session); put_pid(tty->pgrp); tty->session = NULL; tty->pgrp = NULL; tty->ctrl_status = 0; /* * If one of the devices matches a console pointer, we * cannot just call hangup() because that will cause * tty->count and state->count to go out of sync. * So we just call close() the right number of times. */ if (cons_filp) { if (tty->driver->close) for (n = 0; n < closecount; n++) tty->driver->close(tty, cons_filp); } else if (tty->driver->hangup) (tty->driver->hangup)(tty); /* * We don't want to have driver/ldisc interactions beyond * the ones we did here. The driver layer expects no * calls after ->hangup() from the ldisc side. However we * can't yet guarantee all that. */ set_bit(TTY_HUPPED, &tty->flags); if (ld) { tty_ldisc_enable(tty); tty_ldisc_deref(ld); } unlock_kernel(); if (f) fput(f); } /** * tty_hangup - trigger a hangup event * @tty: tty to hangup * * A carrier loss (virtual or otherwise) has occurred on this like * schedule a hangup sequence to run after this event. */ void tty_hangup(struct tty_struct *tty) { #ifdef TTY_DEBUG_HANGUP char buf[64]; printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf)); #endif schedule_work(&tty->hangup_work); } EXPORT_SYMBOL(tty_hangup); /** * tty_vhangup - process vhangup * @tty: tty to hangup * * The user has asked via system call for the terminal to be hung up. * We do this synchronously so that when the syscall returns the process * is complete. That guarantee is necessary for security reasons. */ void tty_vhangup(struct tty_struct *tty) { #ifdef TTY_DEBUG_HANGUP char buf[64]; printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf)); #endif do_tty_hangup(&tty->hangup_work); } EXPORT_SYMBOL(tty_vhangup); /** * tty_hung_up_p - was tty hung up * @filp: file pointer of tty * * Return true if the tty has been subject to a vhangup or a carrier * loss */ int tty_hung_up_p(struct file *filp) { return (filp->f_op == &hung_up_tty_fops); } EXPORT_SYMBOL(tty_hung_up_p); /** * is_tty - checker whether file is a TTY * @filp: file handle that may be a tty * * Check if the file handle is a tty handle. */ int is_tty(struct file *filp) { return filp->f_op->read == tty_read || filp->f_op->read == hung_up_tty_read; } static void session_clear_tty(struct pid *session) { struct task_struct *p; do_each_pid_task(session, PIDTYPE_SID, p) { proc_clear_tty(p); } while_each_pid_task(session, PIDTYPE_SID, p); } /** * disassociate_ctty - disconnect controlling tty * @on_exit: true if exiting so need to "hang up" the session * * This function is typically called only by the session leader, when * it wants to disassociate itself from its controlling tty. * * It performs the following functions: * (1) Sends a SIGHUP and SIGCONT to the foreground process group * (2) Clears the tty from being controlling the session * (3) Clears the controlling tty for all processes in the * session group. * * The argument on_exit is set to 1 if called when a process is * exiting; it is 0 if called by the ioctl TIOCNOTTY. * * Locking: * BKL is taken for hysterical raisins * tty_mutex is taken to protect tty * ->siglock is taken to protect ->signal/->sighand * tasklist_lock is taken to walk process list for sessions * ->siglock is taken to protect ->signal/->sighand */ void disassociate_ctty(int on_exit) { struct tty_struct *tty; struct pid *tty_pgrp = NULL; lock_kernel(); mutex_lock(&tty_mutex); tty = get_current_tty(); if (tty) { tty_pgrp = get_pid(tty->pgrp); mutex_unlock(&tty_mutex); /* XXX: here we race, there is nothing protecting tty */ if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) tty_vhangup(tty); } else if (on_exit) { struct pid *old_pgrp; spin_lock_irq(&current->sighand->siglock); old_pgrp = current->signal->tty_old_pgrp; current->signal->tty_old_pgrp = NULL; spin_unlock_irq(&current->sighand->siglock); if (old_pgrp) { kill_pgrp(old_pgrp, SIGHUP, on_exit); kill_pgrp(old_pgrp, SIGCONT, on_exit); put_pid(old_pgrp); } mutex_unlock(&tty_mutex); unlock_kernel(); return; } if (tty_pgrp) { kill_pgrp(tty_pgrp, SIGHUP, on_exit); if (!on_exit) kill_pgrp(tty_pgrp, SIGCONT, on_exit); put_pid(tty_pgrp); } spin_lock_irq(&current->sighand->siglock); put_pid(current->signal->tty_old_pgrp); current->signal->tty_old_pgrp = NULL; spin_unlock_irq(&current->sighand->siglock); mutex_lock(&tty_mutex); /* It is possible that do_tty_hangup has free'd this tty */ tty = get_current_tty(); if (tty) { put_pid(tty->session); put_pid(tty->pgrp); tty->session = NULL; tty->pgrp = NULL; } else { #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "error attempted to write to tty [0x%p]" " = NULL", tty); #endif } mutex_unlock(&tty_mutex); /* Now clear signal->tty under the lock */ read_lock(&tasklist_lock); session_clear_tty(task_session(current)); read_unlock(&tasklist_lock); unlock_kernel(); } /** * * no_tty - Ensure the current process does not have a controlling tty */ void no_tty(void) { struct task_struct *tsk = current; if (tsk->signal->leader) disassociate_ctty(0); proc_clear_tty(tsk); } /** * stop_tty - propagate flow control * @tty: tty to stop * * Perform flow control to the driver. For PTY/TTY pairs we * must also propagate the TIOCKPKT status. May be called * on an already stopped device and will not re-call the driver * method. * * This functionality is used by both the line disciplines for * halting incoming flow and by the driver. It may therefore be * called from any context, may be under the tty atomic_write_lock * but not always. * * Locking: * Broken. Relies on BKL which is unsafe here. */ void stop_tty(struct tty_struct *tty) { if (tty->stopped) return; tty->stopped = 1; if (tty->link && tty->link->packet) { tty->ctrl_status &= ~TIOCPKT_START; tty->ctrl_status |= TIOCPKT_STOP; wake_up_interruptible(&tty->link->read_wait); } if (tty->driver->stop) (tty->driver->stop)(tty); } EXPORT_SYMBOL(stop_tty); /** * start_tty - propagate flow control * @tty: tty to start * * Start a tty that has been stopped if at all possible. Perform * any necessary wakeups and propagate the TIOCPKT status. If this * is the tty was previous stopped and is being started then the * driver start method is invoked and the line discipline woken. * * Locking: * Broken. Relies on BKL which is unsafe here. */ void start_tty(struct tty_struct *tty) { if (!tty->stopped || tty->flow_stopped) return; tty->stopped = 0; if (tty->link && tty->link->packet) { tty->ctrl_status &= ~TIOCPKT_STOP; tty->ctrl_status |= TIOCPKT_START; wake_up_interruptible(&tty->link->read_wait); } if (tty->driver->start) (tty->driver->start)(tty); /* If we have a running line discipline it may need kicking */ tty_wakeup(tty); } EXPORT_SYMBOL(start_tty); /** * tty_read - read method for tty device files * @file: pointer to tty file * @buf: user buffer * @count: size of user buffer * @ppos: unused * * Perform the read system call function on this terminal device. Checks * for hung up devices before calling the line discipline method. * * Locking: * Locks the line discipline internally while needed * For historical reasons the line discipline read method is * invoked under the BKL. This will go away in time so do not rely on it * in new code. Multiple read calls may be outstanding in parallel. */ static ssize_t tty_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { int i; struct tty_struct *tty; struct inode *inode; struct tty_ldisc *ld; tty = (struct tty_struct *)file->private_data; inode = file->f_path.dentry->d_inode; if (tty_paranoia_check(tty, inode, "tty_read")) return -EIO; if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags))) return -EIO; /* We want to wait for the line discipline to sort out in this situation */ ld = tty_ldisc_ref_wait(tty); lock_kernel(); if (ld->read) i = (ld->read)(tty, file, buf, count); else i = -EIO; tty_ldisc_deref(ld); unlock_kernel(); if (i > 0) inode->i_atime = current_fs_time(inode->i_sb); return i; } void tty_write_unlock(struct tty_struct *tty) { mutex_unlock(&tty->atomic_write_lock); wake_up_interruptible(&tty->write_wait); } int tty_write_lock(struct tty_struct *tty, int ndelay) { if (!mutex_trylock(&tty->atomic_write_lock)) { if (ndelay) return -EAGAIN; if (mutex_lock_interruptible(&tty->atomic_write_lock)) return -ERESTARTSYS; } return 0; } /* * Split writes up in sane blocksizes to avoid * denial-of-service type attacks */ static inline ssize_t do_tty_write( ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t), struct tty_struct *tty, struct file *file, const char __user *buf, size_t count) { ssize_t ret, written = 0; unsigned int chunk; ret = tty_write_lock(tty, file->f_flags & O_NDELAY); if (ret < 0) return ret; /* * We chunk up writes into a temporary buffer. This * simplifies low-level drivers immensely, since they * don't have locking issues and user mode accesses. * * But if TTY_NO_WRITE_SPLIT is set, we should use a * big chunk-size.. * * The default chunk-size is 2kB, because the NTTY * layer has problems with bigger chunks. It will * claim to be able to handle more characters than * it actually does. * * FIXME: This can probably go away now except that 64K chunks * are too likely to fail unless switched to vmalloc... */ chunk = 2048; if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags)) chunk = 65536; if (count < chunk) chunk = count; /* write_buf/write_cnt is protected by the atomic_write_lock mutex */ if (tty->write_cnt < chunk) { unsigned char *buf; if (chunk < 1024) chunk = 1024; buf = kmalloc(chunk, GFP_KERNEL); if (!buf) { ret = -ENOMEM; goto out; } kfree(tty->write_buf); tty->write_cnt = chunk; tty->write_buf = buf; } /* Do the write .. */ for (;;) { size_t size = count; if (size > chunk) size = chunk; ret = -EFAULT; if (copy_from_user(tty->write_buf, buf, size)) break; lock_kernel(); ret = write(tty, file, tty->write_buf, size); unlock_kernel(); if (ret <= 0) break; written += ret; buf += ret; count -= ret; if (!count) break; ret = -ERESTARTSYS; if (signal_pending(current)) break; cond_resched(); } if (written) { struct inode *inode = file->f_path.dentry->d_inode; inode->i_mtime = current_fs_time(inode->i_sb); ret = written; } out: tty_write_unlock(tty); return ret; } /** * tty_write - write method for tty device file * @file: tty file pointer * @buf: user data to write * @count: bytes to write * @ppos: unused * * Write data to a tty device via the line discipline. * * Locking: * Locks the line discipline as required * Writes to the tty driver are serialized by the atomic_write_lock * and are then processed in chunks to the device. The line discipline * write method will not be involked in parallel for each device * The line discipline write method is called under the big * kernel lock for historical reasons. New code should not rely on this. */ static ssize_t tty_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { struct tty_struct *tty; struct inode *inode = file->f_path.dentry->d_inode; ssize_t ret; struct tty_ldisc *ld; tty = (struct tty_struct *)file->private_data; if (tty_paranoia_check(tty, inode, "tty_write")) return -EIO; if (!tty || !tty->driver->write || (test_bit(TTY_IO_ERROR, &tty->flags))) return -EIO; ld = tty_ldisc_ref_wait(tty); if (!ld->write) ret = -EIO; else ret = do_tty_write(ld->write, tty, file, buf, count); tty_ldisc_deref(ld); return ret; } ssize_t redirected_tty_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { struct file *p = NULL; spin_lock(&redirect_lock); if (redirect) { get_file(redirect); p = redirect; } spin_unlock(&redirect_lock); if (p) { ssize_t res; res = vfs_write(p, buf, count, &p->f_pos); fput(p); return res; } return tty_write(file, buf, count, ppos); } static char ptychar[] = "pqrstuvwxyzabcde"; /** * pty_line_name - generate name for a pty * @driver: the tty driver in use * @index: the minor number * @p: output buffer of at least 6 bytes * * Generate a name from a driver reference and write it to the output * buffer. * * Locking: None */ static void pty_line_name(struct tty_driver *driver, int index, char *p) { int i = index + driver->name_base; /* ->name is initialized to "ttyp", but "tty" is expected */ sprintf(p, "%s%c%x", driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name, ptychar[i >> 4 & 0xf], i & 0xf); } /** * pty_line_name - generate name for a tty * @driver: the tty driver in use * @index: the minor number * @p: output buffer of at least 7 bytes * * Generate a name from a driver reference and write it to the output * buffer. * * Locking: None */ static void tty_line_name(struct tty_driver *driver, int index, char *p) { sprintf(p, "%s%d", driver->name, index + driver->name_base); } /** * init_dev - initialise a tty device * @driver: tty driver we are opening a device on * @idx: device index * @tty: returned tty structure * * Prepare a tty device. This may not be a "new" clean device but * could also be an active device. The pty drivers require special * handling because of this. * * Locking: * The function is called under the tty_mutex, which * protects us from the tty struct or driver itself going away. * * On exit the tty device has the line discipline attached and * a reference count of 1. If a pair was created for pty/tty use * and the other was a pty master then it too has a reference count of 1. * * WSH 06/09/97: Rewritten to remove races and properly clean up after a * failed open. The new code protects the open with a mutex, so it's * really quite straightforward. The mutex locking can probably be * relaxed for the (most common) case of reopening a tty. */ static int init_dev(struct tty_driver *driver, int idx, struct tty_struct **ret_tty) { struct tty_struct *tty, *o_tty; struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc; struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc; int retval = 0; /* check whether we're reopening an existing tty */ if (driver->flags & TTY_DRIVER_DEVPTS_MEM) { tty = devpts_get_tty(idx); /* * If we don't have a tty here on a slave open, it's because * the master already started the close process and there's * no relation between devpts file and tty anymore. */ if (!tty && driver->subtype == PTY_TYPE_SLAVE) { retval = -EIO; goto end_init; } /* * It's safe from now on because init_dev() is called with * tty_mutex held and release_dev() won't change tty->count * or tty->flags without having to grab tty_mutex */ if (tty && driver->subtype == PTY_TYPE_MASTER) tty = tty->link; } else { tty = driver->ttys[idx]; } if (tty) goto fast_track; /* * First time open is complex, especially for PTY devices. * This code guarantees that either everything succeeds and the * TTY is ready for operation, or else the table slots are vacated * and the allocated memory released. (Except that the termios * and locked termios may be retained.) */ if (!try_module_get(driver->owner)) { retval = -ENODEV; goto end_init; } o_tty = NULL; tp = o_tp = NULL; ltp = o_ltp = NULL; tty = alloc_tty_struct(); if (!tty) goto fail_no_mem; initialize_tty_struct(tty); tty->driver = driver; tty->index = idx; tty_line_name(driver, idx, tty->name); if (driver->flags & TTY_DRIVER_DEVPTS_MEM) { tp_loc = &tty->termios; ltp_loc = &tty->termios_locked; } else { tp_loc = &driver->termios[idx]; ltp_loc = &driver->termios_locked[idx]; } if (!*tp_loc) { tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL); if (!tp) goto free_mem_out; *tp = driver->init_termios; } if (!*ltp_loc) { ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL); if (!ltp) goto free_mem_out; } if (driver->type == TTY_DRIVER_TYPE_PTY) { o_tty = alloc_tty_struct(); if (!o_tty) goto free_mem_out; initialize_tty_struct(o_tty); o_tty->driver = driver->other; o_tty->index = idx; tty_line_name(driver->other, idx, o_tty->name); if (driver->flags & TTY_DRIVER_DEVPTS_MEM) { o_tp_loc = &o_tty->termios; o_ltp_loc = &o_tty->termios_locked; } else { o_tp_loc = &driver->other->termios[idx]; o_ltp_loc = &driver->other->termios_locked[idx]; } if (!*o_tp_loc) { o_tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL); if (!o_tp) goto free_mem_out; *o_tp = driver->other->init_termios; } if (!*o_ltp_loc) { o_ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL); if (!o_ltp) goto free_mem_out; } /* * Everything allocated ... set up the o_tty structure. */ if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM)) driver->other->ttys[idx] = o_tty; if (!*o_tp_loc) *o_tp_loc = o_tp; if (!*o_ltp_loc) *o_ltp_loc = o_ltp; o_tty->termios = *o_tp_loc; o_tty->termios_locked = *o_ltp_loc; driver->other->refcount++; if (driver->subtype == PTY_TYPE_MASTER) o_tty->count++; /* Establish the links in both directions */ tty->link = o_tty; o_tty->link = tty; } /* * All structures have been allocated, so now we install them. * Failures after this point use release_tty to clean up, so * there's no need to null out the local pointers. */ if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) driver->ttys[idx] = tty; if (!*tp_loc) *tp_loc = tp; if (!*ltp_loc) *ltp_loc = ltp; tty->termios = *tp_loc; tty->termios_locked = *ltp_loc; /* Compatibility until drivers always set this */ tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios); tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios); driver->refcount++; tty->count++; /* * Structures all installed ... call the ldisc open routines. * If we fail here just call release_tty to clean up. No need * to decrement the use counts, as release_tty doesn't care. */ if (tty->ldisc.open) { retval = (tty->ldisc.open)(tty); if (retval) goto release_mem_out; } if (o_tty && o_tty->ldisc.open) { retval = (o_tty->ldisc.open)(o_tty); if (retval) { if (tty->ldisc.close) (tty->ldisc.close)(tty); goto release_mem_out; } tty_ldisc_enable(o_tty); } tty_ldisc_enable(tty); goto success; /* * This fast open can be used if the tty is already open. * No memory is allocated, and the only failures are from * attempting to open a closing tty or attempting multiple * opens on a pty master. */ fast_track: if (test_bit(TTY_CLOSING, &tty->flags)) { retval = -EIO; goto end_init; } if (driver->type == TTY_DRIVER_TYPE_PTY && driver->subtype == PTY_TYPE_MASTER) { /* * special case for PTY masters: only one open permitted, * and the slave side open count is incremented as well. */ if (tty->count) { retval = -EIO; goto end_init; } tty->link->count++; } tty->count++; tty->driver = driver; /* N.B. why do this every time?? */ /* FIXME */ if (!test_bit(TTY_LDISC, &tty->flags)) printk(KERN_ERR "init_dev but no ldisc\n"); success: *ret_tty = tty; /* All paths come through here to release the mutex */ end_init: return retval; /* Release locally allocated memory ... nothing placed in slots */ free_mem_out: kfree(o_tp); if (o_tty) free_tty_struct(o_tty); kfree(ltp); kfree(tp); free_tty_struct(tty); fail_no_mem: module_put(driver->owner); retval = -ENOMEM; goto end_init; /* call the tty release_tty routine to clean out this slot */ release_mem_out: if (printk_ratelimit()) printk(KERN_INFO "init_dev: ldisc open failed, " "clearing slot %d\n", idx); release_tty(tty, idx); goto end_init; } /** * release_one_tty - release tty structure memory * * Releases memory associated with a tty structure, and clears out the * driver table slots. This function is called when a device is no longer * in use. It also gets called when setup of a device fails. * * Locking: * tty_mutex - sometimes only * takes the file list lock internally when working on the list * of ttys that the driver keeps. * FIXME: should we require tty_mutex is held here ?? */ static void release_one_tty(struct tty_struct *tty, int idx) { int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM; struct ktermios *tp; if (!devpts) tty->driver->ttys[idx] = NULL; if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) { tp = tty->termios; if (!devpts) tty->driver->termios[idx] = NULL; kfree(tp); tp = tty->termios_locked; if (!devpts) tty->driver->termios_locked[idx] = NULL; kfree(tp); } tty->magic = 0; tty->driver->refcount--; file_list_lock(); list_del_init(&tty->tty_files); file_list_unlock(); free_tty_struct(tty); } /** * release_tty - release tty structure memory * * Release both @tty and a possible linked partner (think pty pair), * and decrement the refcount of the backing module. * * Locking: * tty_mutex - sometimes only * takes the file list lock internally when working on the list * of ttys that the driver keeps. * FIXME: should we require tty_mutex is held here ?? */ static void release_tty(struct tty_struct *tty, int idx) { struct tty_driver *driver = tty->driver; if (tty->link) release_one_tty(tty->link, idx); release_one_tty(tty, idx); module_put(driver->owner); } /* * Even releasing the tty structures is a tricky business.. We have * to be very careful that the structures are all released at the * same time, as interrupts might otherwise get the wrong pointers. * * WSH 09/09/97: rewritten to avoid some nasty race conditions that could * lead to double frees or releasing memory still in use. */ static void release_dev(struct file *filp) { struct tty_struct *tty, *o_tty; int pty_master, tty_closing, o_tty_closing, do_sleep; int devpts; int idx; char buf[64]; unsigned long flags; tty = (struct tty_struct *)filp->private_data; if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "release_dev")) return; check_tty_count(tty, "release_dev"); tty_fasync(-1, filp, 0); idx = tty->index; pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER); devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0; o_tty = tty->link; #ifdef TTY_PARANOIA_CHECK if (idx < 0 || idx >= tty->driver->num) { printk(KERN_DEBUG "release_dev: bad idx when trying to " "free (%s)\n", tty->name); return; } if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) { if (tty != tty->driver->ttys[idx]) { printk(KERN_DEBUG "release_dev: driver.table[%d] not tty " "for (%s)\n", idx, tty->name); return; } if (tty->termios != tty->driver->termios[idx]) { printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios " "for (%s)\n", idx, tty->name); return; } if (tty->termios_locked != tty->driver->termios_locked[idx]) { printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not " "termios_locked for (%s)\n", idx, tty->name); return; } } #endif #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "release_dev of %s (tty count=%d)...", tty_name(tty, buf), tty->count); #endif #ifdef TTY_PARANOIA_CHECK if (tty->driver->other && !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) { if (o_tty != tty->driver->other->ttys[idx]) { printk(KERN_DEBUG "release_dev: other->table[%d] " "not o_tty for (%s)\n", idx, tty->name); return; } if (o_tty->termios != tty->driver->other->termios[idx]) { printk(KERN_DEBUG "release_dev: other->termios[%d] " "not o_termios for (%s)\n", idx, tty->name); return; } if (o_tty->termios_locked != tty->driver->other->termios_locked[idx]) { printk(KERN_DEBUG "release_dev: other->termios_locked[" "%d] not o_termios_locked for (%s)\n", idx, tty->name); return; } if (o_tty->link != tty) { printk(KERN_DEBUG "release_dev: bad pty pointers\n"); return; } } #endif if (tty->driver->close) tty->driver->close(tty, filp); /* * Sanity check: if tty->count is going to zero, there shouldn't be * any waiters on tty->read_wait or tty->write_wait. We test the * wait queues and kick everyone out _before_ actually starting to * close. This ensures that we won't block while releasing the tty * structure. * * The test for the o_tty closing is necessary, since the master and * slave sides may close in any order. If the slave side closes out * first, its count will be one, since the master side holds an open. * Thus this test wouldn't be triggered at the time the slave closes, * so we do it now. * * Note that it's possible for the tty to be opened again while we're * flushing out waiters. By recalculating the closing flags before * each iteration we avoid any problems. */ while (1) { /* Guard against races with tty->count changes elsewhere and opens on /dev/tty */ mutex_lock(&tty_mutex); tty_closing = tty->count <= 1; o_tty_closing = o_tty && (o_tty->count <= (pty_master ? 1 : 0)); do_sleep = 0; if (tty_closing) { if (waitqueue_active(&tty->read_wait)) { wake_up(&tty->read_wait); do_sleep++; } if (waitqueue_active(&tty->write_wait)) { wake_up(&tty->write_wait); do_sleep++; } } if (o_tty_closing) { if (waitqueue_active(&o_tty->read_wait)) { wake_up(&o_tty->read_wait); do_sleep++; } if (waitqueue_active(&o_tty->write_wait)) { wake_up(&o_tty->write_wait); do_sleep++; } } if (!do_sleep) break; printk(KERN_WARNING "release_dev: %s: read/write wait queue " "active!\n", tty_name(tty, buf)); mutex_unlock(&tty_mutex); schedule(); } /* * The closing flags are now consistent with the open counts on * both sides, and we've completed the last operation that could * block, so it's safe to proceed with closing. */ if (pty_master) { if (--o_tty->count < 0) { printk(KERN_WARNING "release_dev: bad pty slave count " "(%d) for %s\n", o_tty->count, tty_name(o_tty, buf)); o_tty->count = 0; } } if (--tty->count < 0) { printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n", tty->count, tty_name(tty, buf)); tty->count = 0; } /* * We've decremented tty->count, so we need to remove this file * descriptor off the tty->tty_files list; this serves two * purposes: * - check_tty_count sees the correct number of file descriptors * associated with this tty. * - do_tty_hangup no longer sees this file descriptor as * something that needs to be handled for hangups. */ file_kill(filp); filp->private_data = NULL; /* * Perform some housekeeping before deciding whether to return. * * Set the TTY_CLOSING flag if this was the last open. In the * case of a pty we may have to wait around for the other side * to close, and TTY_CLOSING makes sure we can't be reopened. */ if (tty_closing) set_bit(TTY_CLOSING, &tty->flags); if (o_tty_closing) set_bit(TTY_CLOSING, &o_tty->flags); /* * If _either_ side is closing, make sure there aren't any * processes that still think tty or o_tty is their controlling * tty. */ if (tty_closing || o_tty_closing) { read_lock(&tasklist_lock); session_clear_tty(tty->session); if (o_tty) session_clear_tty(o_tty->session); read_unlock(&tasklist_lock); } mutex_unlock(&tty_mutex); /* check whether both sides are closing ... */ if (!tty_closing || (o_tty && !o_tty_closing)) return; #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "freeing tty structure..."); #endif /* * Prevent flush_to_ldisc() from rescheduling the work for later. Then * kill any delayed work. As this is the final close it does not * race with the set_ldisc code path. */ clear_bit(TTY_LDISC, &tty->flags); cancel_delayed_work(&tty->buf.work); /* * Wait for ->hangup_work and ->buf.work handlers to terminate */ flush_scheduled_work(); /* * Wait for any short term users (we know they are just driver * side waiters as the file is closing so user count on the file * side is zero. */ spin_lock_irqsave(&tty_ldisc_lock, flags); while (tty->ldisc.refcount) { spin_unlock_irqrestore(&tty_ldisc_lock, flags); wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0); spin_lock_irqsave(&tty_ldisc_lock, flags); } spin_unlock_irqrestore(&tty_ldisc_lock, flags); /* * Shutdown the current line discipline, and reset it to N_TTY. * N.B. why reset ldisc when we're releasing the memory?? * * FIXME: this MUST get fixed for the new reflocking */ if (tty->ldisc.close) (tty->ldisc.close)(tty); tty_ldisc_put(tty->ldisc.num); /* * Switch the line discipline back */ tty_ldisc_assign(tty, tty_ldisc_get(N_TTY)); tty_set_termios_ldisc(tty, N_TTY); if (o_tty) { /* FIXME: could o_tty be in setldisc here ? */ clear_bit(TTY_LDISC, &o_tty->flags); if (o_tty->ldisc.close) (o_tty->ldisc.close)(o_tty); tty_ldisc_put(o_tty->ldisc.num); tty_ldisc_assign(o_tty, tty_ldisc_get(N_TTY)); tty_set_termios_ldisc(o_tty, N_TTY); } /* * The release_tty function takes care of the details of clearing * the slots and preserving the termios structure. */ release_tty(tty, idx); #ifdef CONFIG_UNIX98_PTYS /* Make this pty number available for reallocation */ if (devpts) { mutex_lock(&allocated_ptys_lock); idr_remove(&allocated_ptys, idx); mutex_unlock(&allocated_ptys_lock); } #endif } /** * tty_open - open a tty device * @inode: inode of device file * @filp: file pointer to tty * * tty_open and tty_release keep up the tty count that contains the * number of opens done on a tty. We cannot use the inode-count, as * different inodes might point to the same tty. * * Open-counting is needed for pty masters, as well as for keeping * track of serial lines: DTR is dropped when the last close happens. * (This is not done solely through tty->count, now. - Ted 1/27/92) * * The termios state of a pty is reset on first open so that * settings don't persist across reuse. * * Locking: tty_mutex protects tty, get_tty_driver and init_dev work. * tty->count should protect the rest. * ->siglock protects ->signal/->sighand */ static int tty_open(struct inode *inode, struct file *filp) { struct tty_struct *tty; int noctty, retval; struct tty_driver *driver; int index; dev_t device = inode->i_rdev; unsigned short saved_flags = filp->f_flags; nonseekable_open(inode, filp); retry_open: noctty = filp->f_flags & O_NOCTTY; index = -1; retval = 0; mutex_lock(&tty_mutex); if (device == MKDEV(TTYAUX_MAJOR, 0)) { tty = get_current_tty(); if (!tty) { mutex_unlock(&tty_mutex); return -ENXIO; } driver = tty->driver; index = tty->index; filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */ /* noctty = 1; */ goto got_driver; } #ifdef CONFIG_VT if (device == MKDEV(TTY_MAJOR, 0)) { extern struct tty_driver *console_driver; driver = console_driver; index = fg_console; noctty = 1; goto got_driver; } #endif if (device == MKDEV(TTYAUX_MAJOR, 1)) { driver = console_device(&index); if (driver) { /* Don't let /dev/console block */ filp->f_flags |= O_NONBLOCK; noctty = 1; goto got_driver; } mutex_unlock(&tty_mutex); return -ENODEV; } driver = get_tty_driver(device, &index); if (!driver) { mutex_unlock(&tty_mutex); return -ENODEV; } got_driver: retval = init_dev(driver, index, &tty); mutex_unlock(&tty_mutex); if (retval) return retval; filp->private_data = tty; file_move(filp, &tty->tty_files); check_tty_count(tty, "tty_open"); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER) noctty = 1; #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "opening %s...", tty->name);


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