tty: Introduce a tty_port generic block_til_ready

Start sucking more commonality out of the drivers into a single piece of
core code.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

7 files changed, 115 insertions, 235 deletions

diff --git a/drivers/char/isicom.c b/drivers/char/isicom.c
index db53db91ae4a..bac55cf44243 100644
--- a/drivers/char/isicom.c
+++ b/drivers/char/isicom.c
@@ -838,82 +838,6 @@ static int isicom_carrier_raised(struct tty_port *port)
         return (ip->status & ISI_DCD)?1 : 0;
 }
 
-static int block_til_ready(struct tty_struct *tty, struct file *filp,
-        struct isi_port *ip)
-{
-        struct tty_port *port = &ip->port;
-        int do_clocal = 0, retval;
-        unsigned long flags;
-        DECLARE_WAITQUEUE(wait, current);
-        int cd;
-
-        /* block if port is in the process of being closed */
-
-        if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
-                pr_dbg("block_til_ready: close in progress.\n");
-                interruptible_sleep_on(&port->close_wait);
-                if (port->flags & ASYNC_HUP_NOTIFY)
-                        return -EAGAIN;
-                else
-                        return -ERESTARTSYS;
-        }
-
-        /* if non-blocking mode is set ... */
-
-        if ((filp->f_flags & O_NONBLOCK) ||
-                        (tty->flags & (1 << TTY_IO_ERROR))) {
-                pr_dbg("block_til_ready: non-block mode.\n");
-                port->flags |= ASYNC_NORMAL_ACTIVE;
-                return 0;
-        }
-
-        if (C_CLOCAL(tty))
-                do_clocal = 1;
-
-        /* block waiting for DCD to be asserted, and while
-                                                callout dev is busy */
-        retval = 0;
-        add_wait_queue(&port->open_wait, &wait);
-
-        spin_lock_irqsave(&port->lock, flags);
-        if (!tty_hung_up_p(filp))
-                port->count--;
-        port->blocked_open++;
-        spin_unlock_irqrestore(&port->lock, flags);
-
-        while (1) {
-                tty_port_raise_dtr_rts(port);
-
-                set_current_state(TASK_INTERRUPTIBLE);
-                if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) {
-                        if (port->flags & ASYNC_HUP_NOTIFY)
-                                retval = -EAGAIN;
-                        else
-                                retval = -ERESTARTSYS;
-                        break;
-                }
-                cd = tty_port_carrier_raised(port);
-                if (!(port->flags & ASYNC_CLOSING) &&
-                                (do_clocal || cd))
-                        break;
-                if (signal_pending(current)) {
-                        retval = -ERESTARTSYS;
-                        break;
-                }
-                schedule();
-        }
-        set_current_state(TASK_RUNNING);
-        remove_wait_queue(&port->open_wait, &wait);
-        spin_lock_irqsave(&port->lock, flags);
-        if (!tty_hung_up_p(filp))
-                port->count++;
-        port->blocked_open--;
-        if (retval == 0)
-                port->flags |= ASYNC_NORMAL_ACTIVE;
-        spin_unlock_irqrestore(&port->lock, flags);
-        return 0;
-}
-
 static int isicom_open(struct tty_struct *tty, struct file *filp)
 {
         struct isi_port *port;
@@ -940,12 +864,13 @@ static int isicom_open(struct tty_struct *tty, struct file *filp)
 
         isicom_setup_board(card);
 
+        /* FIXME: locking on port.count etc */
         port->port.count++;
         tty->driver_data = port;
         tty_port_tty_set(&port->port, tty);
         error = isicom_setup_port(tty);
         if (error == 0)
-                error = block_til_ready(tty, filp, port);
+                error = tty_port_block_til_ready(&port->port, tty, filp);
         return error;
 }
 
diff --git a/drivers/char/mxser.c b/drivers/char/mxser.c
index e2471cf1ee95..08ba6eb1a380 100644
--- a/drivers/char/mxser.c
+++ b/drivers/char/mxser.c
@@ -558,75 +558,6 @@ static void mxser_raise_dtr_rts(struct tty_port *port)
         spin_unlock_irqrestore(&mp->slock, flags);
 }
 
-static int mxser_block_til_ready(struct tty_struct *tty, struct file *filp,
-                struct mxser_port *mp)
-{
-        DECLARE_WAITQUEUE(wait, current);
-        int retval;
-        int do_clocal = 0;
-        unsigned long flags;
-        int cd;
-        struct tty_port *port = &mp->port;
-
-        /*
-         * If non-blocking mode is set, or the port is not enabled,
-         * then make the check up front and then exit.
-         */
-        if ((filp->f_flags & O_NONBLOCK) ||
-                        test_bit(TTY_IO_ERROR, &tty->flags)) {
-                port->flags |= ASYNC_NORMAL_ACTIVE;
-                return 0;
-        }
-
-        if (tty->termios->c_cflag & CLOCAL)
-                do_clocal = 1;
-
-        /*
-         * Block waiting for the carrier detect and the line to become
-         * free (i.e., not in use by the callout).  While we are in
-         * this loop, port->count is dropped by one, so that
-         * mxser_close() knows when to free things.  We restore it upon
-         * exit, either normal or abnormal.
-         */
-        retval = 0;
-        add_wait_queue(&port->open_wait, &wait);
-
-        spin_lock_irqsave(&port->lock, flags);
-        if (!tty_hung_up_p(filp))
-                port->count--;
-        port->blocked_open++;
-        spin_unlock_irqrestore(&port->lock, flags);
-        while (1) {
-                tty_port_raise_dtr_rts(port);
-                set_current_state(TASK_INTERRUPTIBLE);
-                if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) {
-                        if (port->flags & ASYNC_HUP_NOTIFY)
-                                retval = -EAGAIN;
-                        else
-                                retval = -ERESTARTSYS;
-                        break;
-                }
-                cd = tty_port_carrier_raised(port);
-                if (!(port->flags & ASYNC_CLOSING) && (do_clocal || cd))
-                        break;
-                if (signal_pending(current)) {
-                        retval = -ERESTARTSYS;
-                        break;
-                }
-                schedule();
-        }
-        set_current_state(TASK_RUNNING);
-        remove_wait_queue(&port->open_wait, &wait);
-        spin_lock_irqsave(&port->lock, flags);
-        if (!tty_hung_up_p(filp))
-                port->count++;
-        port->blocked_open--;
-        if (retval == 0)
-                port->flags |= ASYNC_NORMAL_ACTIVE;
-        spin_unlock_irqrestore(&port->lock, flags);
-        return 0;
-}
-
 static int mxser_set_baud(struct tty_struct *tty, long newspd)
 {
         struct mxser_port *info = tty->driver_data;
@@ -1110,7 +1041,7 @@ static int mxser_open(struct tty_struct *tty, struct file *filp)
         if (retval)
                 return retval;
 
-        retval = mxser_block_til_ready(tty, filp, info);
+        retval = tty_port_block_til_ready(&info->port, tty, filp);
         if (retval)
                 return retval;
 
diff --git a/drivers/char/riscom8.c b/drivers/char/riscom8.c
index 14662d7aa628..af34c2054a09 100644
--- a/drivers/char/riscom8.c
+++ b/drivers/char/riscom8.c
@@ -874,90 +874,6 @@ static int carrier_raised(struct tty_port *port)
         return CD;
 }
 
-static int block_til_ready(struct tty_struct *tty, struct file *filp,
-                           struct riscom_port *rp)
-{
-        DECLARE_WAITQUEUE(wait, current);
-        int    retval;
-        int    do_clocal = 0;
-        int    CD;
-        unsigned long flags;
-        struct tty_port *port = &rp->port;
-
-        /*
-         * If the device is in the middle of being closed, then block
-         * until it's done, and then try again.
-         */
-        if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
-                interruptible_sleep_on(&port->close_wait);
-                if (port->flags & ASYNC_HUP_NOTIFY)
-                        return -EAGAIN;
-                else
-                        return -ERESTARTSYS;
-        }
-
-        /*
-         * If non-blocking mode is set, or the port is not enabled,
-         * then make the check up front and then exit.
-         */
-        if ((filp->f_flags & O_NONBLOCK) ||
-            (tty->flags & (1 << TTY_IO_ERROR))) {
-                port->flags |= ASYNC_NORMAL_ACTIVE;
-                return 0;
-        }
-
-        if (C_CLOCAL(tty))
-                do_clocal = 1;
-
-        /*
-         * Block waiting for the carrier detect and the line to become
-         * free (i.e., not in use by the callout).  While we are in
-         * this loop, info->count is dropped by one, so that
-         * rs_close() knows when to free things.  We restore it upon
-         * exit, either normal or abnormal.
-         */
-        retval = 0;
-        add_wait_queue(&port->open_wait, &wait);
-
-        spin_lock_irqsave(&port->lock, flags);
-        if (!tty_hung_up_p(filp))
-                port->count--;
-        port->blocked_open++;
-        spin_unlock_irqrestore(&port->lock, flags);
-
-        while (1) {
-
-                CD = tty_port_carrier_raised(port);
-                set_current_state(TASK_INTERRUPTIBLE);
-                if (tty_hung_up_p(filp) ||
-                    !(port->flags & ASYNC_INITIALIZED)) {
-                        if (port->flags & ASYNC_HUP_NOTIFY)
-                                retval = -EAGAIN;
-                        else
-                                retval = -ERESTARTSYS;
-                        break;
-                }
-                if (!(port->flags & ASYNC_CLOSING) &&
-                    (do_clocal || CD))
-                        break;
-                if (signal_pending(current)) {
-                        retval = -ERESTARTSYS;
-                        break;
-                }
-                schedule();
-        }
-        __set_current_state(TASK_RUNNING);
-        remove_wait_queue(&port->open_wait, &wait);
-        spin_lock_irqsave(&port->lock, flags);
-        if (!tty_hung_up_p(filp))
-                port->count++;
-        port->blocked_open--;
-        if (retval == 0)
-                port->flags |= ASYNC_NORMAL_ACTIVE;
-        spin_unlock_irqrestore(&port->lock, flags);
-        return 0;
-}
-
 static int rc_open(struct tty_struct *tty, struct file *filp)
 {
         int board;
@@ -984,7 +900,7 @@ static int rc_open(struct tty_struct *tty, struct file *filp)
 
         error = rc_setup_port(bp, port);
         if (error == 0)
-                error = block_til_ready(tty, filp, port);
+                error = tty_port_block_til_ready(&port->port, tty, filp);
         return error;
 }
 
diff --git a/drivers/char/synclink.c b/drivers/char/synclink.c
index ac9f21e18c3f..0ded4ed3da3c 100644
--- a/drivers/char/synclink.c
+++ b/drivers/char/synclink.c
@@ -3401,6 +3401,7 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
         set_current_state(TASK_RUNNING);
         remove_wait_queue(&port->open_wait, &wait);
         
+        /* FIXME: Racy on hangup during close wait */
         if (extra_count)
                 port->count++;
         port->blocked_open--;
diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 9f418bca4a22..ff94182b3813 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -151,3 +151,108 @@ void tty_port_raise_dtr_rts(struct tty_port *port)
                 port->ops->raise_dtr_rts(port);
 }
 EXPORT_SYMBOL(tty_port_raise_dtr_rts);
+
+/**
+ *      tty_port_block_til_ready        -       Waiting logic for tty open
+ *      @port: the tty port being opened
+ *      @tty: the tty device being bound
+ *      @filp: the file pointer of the opener
+ *
+ *      Implement the core POSIX/SuS tty behaviour when opening a tty device.
+ *      Handles:
+ *              - hangup (both before and during)
+ *              - non blocking open
+ *              - rts/dtr/dcd
+ *              - signals
+ *              - port flags and counts
+ *
+ *      The passed tty_port must implement the carrier_raised method if it can
+ *      do carrier detect and the raise_dtr_rts method if it supports software
+ *      management of these lines. Note that the dtr/rts raise is done each
+ *      iteration as a hangup may have previously dropped them while we wait.
+ */
+ 
+int tty_port_block_til_ready(struct tty_port *port,
+                                struct tty_struct *tty, struct file *filp)
+{
+        int do_clocal = 0, retval;
+        unsigned long flags;
+        DECLARE_WAITQUEUE(wait, current);
+        int cd;
+
+        /* block if port is in the process of being closed */
+        if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
+                interruptible_sleep_on(&port->close_wait);
+                if (port->flags & ASYNC_HUP_NOTIFY)
+                        return -EAGAIN;
+                else
+                        return -ERESTARTSYS;
+        }
+
+        /* if non-blocking mode is set we can pass directly to open unless
+           the port has just hung up or is in another error state */
+        if ((filp->f_flags & O_NONBLOCK) ||
+                        (tty->flags & (1 << TTY_IO_ERROR))) {
+                port->flags |= ASYNC_NORMAL_ACTIVE;
+                return 0;
+        }
+
+        if (C_CLOCAL(tty))
+                do_clocal = 1;
+
+        /* Block waiting until we can proceed. We may need to wait for the
+           carrier, but we must also wait for any close that is in progress
+           before the next open may complete */
+
+        retval = 0;
+        add_wait_queue(&port->open_wait, &wait);
+
+        /* The port lock protects the port counts */
+        spin_lock_irqsave(&port->lock, flags);
+        if (!tty_hung_up_p(filp))
+                port->count--;
+        port->blocked_open++;
+        spin_unlock_irqrestore(&port->lock, flags);
+
+        while (1) {
+                /* Indicate we are open */
+                tty_port_raise_dtr_rts(port);
+
+                set_current_state(TASK_INTERRUPTIBLE);
+                /* Check for a hangup or uninitialised port. Return accordingly */
+                if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) {
+                        if (port->flags & ASYNC_HUP_NOTIFY)
+                                retval = -EAGAIN;
+                        else
+                                retval = -ERESTARTSYS;
+                        break;
+                }
+                /* Probe the carrier. For devices with no carrier detect this
+                   will always return true */
+                cd = tty_port_carrier_raised(port);
+                if (!(port->flags & ASYNC_CLOSING) &&
+                                (do_clocal || cd))
+                        break;
+                if (signal_pending(current)) {
+                        retval = -ERESTARTSYS;
+                        break;
+                }
+                schedule();
+        }
+        set_current_state(TASK_RUNNING);
+        remove_wait_queue(&port->open_wait, &wait);
+
+        /* Update counts. A parallel hangup will have set count to zero and
+           we must not mess that up further */
+        spin_lock_irqsave(&port->lock, flags);
+        if (!tty_hung_up_p(filp))
+                port->count++;
+        port->blocked_open--;
+        if (retval == 0)
+                port->flags |= ASYNC_NORMAL_ACTIVE;
+        spin_unlock_irqrestore(&port->lock, flags);
+        return 0;
+        
+}
+EXPORT_SYMBOL(tty_port_block_til_ready);
+
diff --git a/drivers/char/vme_scc.c b/drivers/char/vme_scc.c
index d4e1534c0e03..2d9242a45a0d 100644
--- a/drivers/char/vme_scc.c
+++ b/drivers/char/vme_scc.c
@@ -631,8 +631,8 @@ static void scc_enable_rx_interrupts(void *ptr)
 
 static int scc_carrier_raised(struct tty_port *port)
 {
-        struct scc_port *scc = container_of(port, struct scc_port, gs.port);
-        unsigned channel = port->channel;
+        struct scc_port *sc = container_of(port, struct scc_port, gs.port);
+        unsigned channel = sc->channel;
 
         return !!(scc_last_status_reg[channel] & SR_DCD);
 }
@@ -643,7 +643,7 @@ static void scc_shutdown_port(void *ptr)
         struct scc_port *port = ptr;
 
         port->gs.port.flags &= ~ GS_ACTIVE;
-        if (port->gs.port.tty && port->gs.port.tty->termios->c_cflag & HUPCL) {
+        if (port->gs.port.tty && (port->gs.port.tty->termios->c_cflag & HUPCL)) {
                 scc_setsignals (port, 0, 0);
         }
 }
diff --git a/include/linux/tty.h b/include/linux/tty.h
index a1a93140e6e4..61a0ab32cf11 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -439,6 +439,8 @@ extern void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
 extern int tty_port_carrier_raised(struct tty_port *port);
 extern void tty_port_raise_dtr_rts(struct tty_port *port);
 extern void tty_port_hangup(struct tty_port *port);
+extern int tty_port_block_til_ready(struct tty_port *port,
+                                struct tty_struct *tty, struct file *filp);
 
 extern int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc);
 extern int tty_unregister_ldisc(int disc);