tty/serial: lay the foundations for the next set of reworks

- Stop drivers calling their own flush method indirectly, it obfuscates code
  and it will change soon anyway

- A few more lock_kernel paths temporarily needed in some driver internal
  waiting code

- Remove private put_char method that does a write call for one char - we
  have that anyway

- Most but not yet all of the termios copy under lock fixing (some has other
  dependencies to follow)

- Note a few locking bugs in drivers found in the process

- Kill remaining [ab]users of TIOCG/SSOFTCAR in the driver, these must go to
  fix the termios locking

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

26 files changed, 189 insertions, 234 deletions

diff --git a/drivers/char/amiserial.c b/drivers/char/amiserial.c
index 8ab75a43231b..a5f3956a5971 100644
--- a/drivers/char/amiserial.c
+++ b/drivers/char/amiserial.c
@@ -1505,8 +1505,7 @@ static void rs_close(struct tty_struct *tty, struct file * filp)
                 rs_wait_until_sent(tty, info->timeout);
         }
         shutdown(info);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        rs_flush_buffer(tty);
                 
         tty_ldisc_flush(tty);
         tty->closing = 0;
@@ -1539,6 +1538,8 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
                 return; /* Just in case.... */
 
         orig_jiffies = jiffies;
+
+        lock_kernel();
         /*
          * Set the check interval to be 1/5 of the estimated time to
          * send a single character, and make it at least 1.  The check
@@ -1579,6 +1580,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
                         break;
         }
         __set_current_state(TASK_RUNNING);
+        unlock_kernel();
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
         printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
 #endif
diff --git a/drivers/char/cyclades.c b/drivers/char/cyclades.c
index e61939d3331d..571e4fab5bfa 100644
--- a/drivers/char/cyclades.c
+++ b/drivers/char/cyclades.c
@@ -2522,6 +2522,7 @@ static void cy_wait_until_sent(struct tty_struct *tty, int timeout)
                 return;         /* Just in case.... */
 
         orig_jiffies = jiffies;
+        lock_kernel();
         /*
          * Set the check interval to be 1/5 of the estimated time to
          * send a single character, and make it at least 1.  The check
@@ -2573,11 +2574,47 @@ static void cy_wait_until_sent(struct tty_struct *tty, int timeout)
         }
         /* Run one more char cycle */
         msleep_interruptible(jiffies_to_msecs(char_time * 5));
+        unlock_kernel();
 #ifdef CY_DEBUG_WAIT_UNTIL_SENT
         printk(KERN_DEBUG "Clean (jiff=%lu)...done\n", jiffies);
 #endif
 }
 
+static void cy_flush_buffer(struct tty_struct *tty)
+{
+        struct cyclades_port *info = tty->driver_data;
+        struct cyclades_card *card;
+        int channel, retval;
+        unsigned long flags;
+
+#ifdef CY_DEBUG_IO
+        printk(KERN_DEBUG "cyc:cy_flush_buffer ttyC%d\n", info->line);
+#endif
+
+        if (serial_paranoia_check(info, tty->name, "cy_flush_buffer"))
+                return;
+
+        card = info->card;
+        channel = info->line - card->first_line;
+
+        spin_lock_irqsave(&card->card_lock, flags);
+        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
+        spin_unlock_irqrestore(&card->card_lock, flags);
+
+        if (IS_CYC_Z(*card)) {  /* If it is a Z card, flush the on-board
+                                           buffers as well */
+                spin_lock_irqsave(&card->card_lock, flags);
+                retval = cyz_issue_cmd(card, channel, C_CM_FLUSH_TX, 0L);
+                if (retval != 0) {
+                        printk(KERN_ERR "cyc: flush_buffer retval on ttyC%d "
+                                "was %x\n", info->line, retval);
+                }
+                spin_unlock_irqrestore(&card->card_lock, flags);
+        }
+        tty_wakeup(tty);
+}                               /* cy_flush_buffer */
+
+
 /*
  * This routine is called when a particular tty device is closed.
  */
@@ -2689,8 +2726,7 @@ static void cy_close(struct tty_struct *tty, struct file *filp)
 
         spin_unlock_irqrestore(&card->card_lock, flags);
         shutdown(info);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        cy_flush_buffer(tty);
         tty_ldisc_flush(tty);
         spin_lock_irqsave(&card->card_lock, flags);
 
@@ -2881,6 +2917,7 @@ static int cy_chars_in_buffer(struct tty_struct *tty)
                 int char_count;
                 __u32 tx_put, tx_get, tx_bufsize;
 
+                lock_kernel();
                 firm_id = card->base_addr + ID_ADDRESS;
                 zfw_ctrl = card->base_addr +
                         (readl(&firm_id->zfwctrl_addr) & 0xfffff);
@@ -2898,6 +2935,7 @@ static int cy_chars_in_buffer(struct tty_struct *tty)
                 printk(KERN_DEBUG "cyc:cy_chars_in_buffer ttyC%d %d\n",
                         info->line, info->xmit_cnt + char_count);
 #endif
+                unlock_kernel();
                 return info->xmit_cnt + char_count;
         }
 #endif                          /* Z_EXT_CHARS_IN_BUFFER */
@@ -4271,40 +4309,6 @@ static void cy_start(struct tty_struct *tty)
         }
 }                               /* cy_start */
 
-static void cy_flush_buffer(struct tty_struct *tty)
-{
-        struct cyclades_port *info = tty->driver_data;
-        struct cyclades_card *card;
-        int channel, retval;
-        unsigned long flags;
-
-#ifdef CY_DEBUG_IO
-        printk(KERN_DEBUG "cyc:cy_flush_buffer ttyC%d\n", info->line);
-#endif
-
-        if (serial_paranoia_check(info, tty->name, "cy_flush_buffer"))
-                return;
-
-        card = info->card;
-        channel = info->line - card->first_line;
-
-        spin_lock_irqsave(&card->card_lock, flags);
-        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
-        spin_unlock_irqrestore(&card->card_lock, flags);
-
-        if (IS_CYC_Z(*card)) {  /* If it is a Z card, flush the on-board
-                                           buffers as well */
-                spin_lock_irqsave(&card->card_lock, flags);
-                retval = cyz_issue_cmd(card, channel, C_CM_FLUSH_TX, 0L);
-                if (retval != 0) {
-                        printk(KERN_ERR "cyc: flush_buffer retval on ttyC%d "
-                                "was %x\n", info->line, retval);
-                }
-                spin_unlock_irqrestore(&card->card_lock, flags);
-        }
-        tty_wakeup(tty);
-}                               /* cy_flush_buffer */
-
 /*
  * cy_hangup() --- called by tty_hangup() when a hangup is signaled.
  */
diff --git a/drivers/char/epca.c b/drivers/char/epca.c
index 37d4dca5a5d4..39c6a36e395b 100644
--- a/drivers/char/epca.c
+++ b/drivers/char/epca.c
@@ -157,7 +157,6 @@ static void epca_error(int, char *);
 static void pc_close(struct tty_struct *, struct file *);
 static void shutdown(struct channel *);
 static void pc_hangup(struct tty_struct *);
-static void pc_put_char(struct tty_struct *, unsigned char);
 static int pc_write_room(struct tty_struct *);
 static int pc_chars_in_buffer(struct tty_struct *);
 static void pc_flush_buffer(struct tty_struct *);
@@ -459,8 +458,7 @@ static void pc_close(struct tty_struct *tty, struct file *filp)
                         setup_empty_event(tty, ch);
                         tty_wait_until_sent(tty, 3000); /* 30 seconds timeout */
                 }
-                if (tty->driver->flush_buffer)
-                        tty->driver->flush_buffer(tty);
+                pc_flush_buffer(tty);
 
                 tty_ldisc_flush(tty);
                 shutdown(ch);
@@ -532,8 +530,7 @@ static void pc_hangup(struct tty_struct *tty)
         if ((ch = verifyChannel(tty)) != NULL) {
                 unsigned long flags;
 
-                if (tty->driver->flush_buffer)
-                        tty->driver->flush_buffer(tty);
+                pc_flush_buffer(tty);
                 tty_ldisc_flush(tty);
                 shutdown(ch);
 
@@ -645,11 +642,6 @@ static int pc_write(struct tty_struct *tty,
         return amountCopied;
 }
 
-static void pc_put_char(struct tty_struct *tty, unsigned char c)
-{
-        pc_write(tty, &c, 1);
-}
-
 static int pc_write_room(struct tty_struct *tty)
 {
         int remain;
@@ -1035,7 +1027,6 @@ static const struct tty_operations pc_ops = {
         .flush_buffer = pc_flush_buffer,
         .chars_in_buffer = pc_chars_in_buffer,
         .flush_chars = pc_flush_chars,
-        .put_char = pc_put_char,
         .ioctl = pc_ioctl,
         .set_termios = pc_set_termios,
         .stop = pc_stop,
diff --git a/drivers/char/esp.c b/drivers/char/esp.c
index 662e9cfdcc96..b1f92db31331 100644
--- a/drivers/char/esp.c
+++ b/drivers/char/esp.c
@@ -1994,8 +1994,7 @@ static void rs_close(struct tty_struct *tty, struct file * filp)
                 rs_wait_until_sent(tty, info->timeout);
         }
         shutdown(info);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        rs_flush_buffer(tty);
         tty_ldisc_flush(tty);
         tty->closing = 0;
         info->tty = NULL;
diff --git a/drivers/char/generic_serial.c b/drivers/char/generic_serial.c
index 7ed7da1d99cf..f6610f28d657 100644
--- a/drivers/char/generic_serial.c
+++ b/drivers/char/generic_serial.c
@@ -586,8 +586,7 @@ void gs_close(struct tty_struct * tty, struct file * filp)
 
         port->flags &= ~GS_ACTIVE;
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        gs_flush_buffer(tty);
 
         tty_ldisc_flush(tty);
         tty->closing = 0;
diff --git a/drivers/char/isicom.c b/drivers/char/isicom.c
index a69e4bb91ad4..6812fda20953 100644
--- a/drivers/char/isicom.c
+++ b/drivers/char/isicom.c
@@ -1012,6 +1012,22 @@ static void isicom_shutdown_port(struct isi_port *port)
         }
 }
 
+static void isicom_flush_buffer(struct tty_struct *tty)
+{
+        struct isi_port *port = tty->driver_data;
+        struct isi_board *card = port->card;
+        unsigned long flags;
+
+        if (isicom_paranoia_check(port, tty->name, "isicom_flush_buffer"))
+                return;
+
+        spin_lock_irqsave(&card->card_lock, flags);
+        port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
+        spin_unlock_irqrestore(&card->card_lock, flags);
+
+        tty_wakeup(tty);
+}
+
 static void isicom_close(struct tty_struct *tty, struct file *filp)
 {
         struct isi_port *port = tty->driver_data;
@@ -1065,8 +1081,7 @@ static void isicom_close(struct tty_struct *tty, struct file *filp)
         isicom_shutdown_port(port);
         spin_unlock_irqrestore(&card->card_lock, flags);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        isicom_flush_buffer(tty);
         tty_ldisc_flush(tty);
 
         spin_lock_irqsave(&card->card_lock, flags);
@@ -1447,22 +1462,6 @@ static void isicom_hangup(struct tty_struct *tty)
         wake_up_interruptible(&port->open_wait);
 }
 
-/* flush_buffer et all */
-static void isicom_flush_buffer(struct tty_struct *tty)
-{
-        struct isi_port *port = tty->driver_data;
-        struct isi_board *card = port->card;
-        unsigned long flags;
-
-        if (isicom_paranoia_check(port, tty->name, "isicom_flush_buffer"))
-                return;
-
-        spin_lock_irqsave(&card->card_lock, flags);
-        port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
-        spin_unlock_irqrestore(&card->card_lock, flags);
-
-        tty_wakeup(tty);
-}
 
 /*
  * Driver init and deinit functions
diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index 1ab9517c24c5..585fac179ec6 100644
--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -1280,6 +1280,7 @@ static int moxa_chars_in_buffer(struct tty_struct *tty)
          */
         if (ch == NULL)
                 return 0;
+        lock_kernel();
         chars = MoxaPortTxQueue(ch);
         if (chars) {
                 /*
@@ -1289,6 +1290,7 @@ static int moxa_chars_in_buffer(struct tty_struct *tty)
                 if (!(ch->statusflags & EMPTYWAIT))
                         moxa_setup_empty_event(tty);
         }
+        unlock_kernel();
         return chars;
 }
 
diff --git a/drivers/char/mxser.c b/drivers/char/mxser.c
index 00cf09aa11fc..28f63566ab8a 100644
--- a/drivers/char/mxser.c
+++ b/drivers/char/mxser.c
@@ -927,6 +927,27 @@ static int mxser_open(struct tty_struct *tty, struct file *filp)
         return 0;
 }
 
+static void mxser_flush_buffer(struct tty_struct *tty)
+{
+        struct mxser_port *info = tty->driver_data;
+        char fcr;
+        unsigned long flags;
+
+
+        spin_lock_irqsave(&info->slock, flags);
+        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
+
+        fcr = inb(info->ioaddr + UART_FCR);
+        outb((fcr | UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT),
+                info->ioaddr + UART_FCR);
+        outb(fcr, info->ioaddr + UART_FCR);
+
+        spin_unlock_irqrestore(&info->slock, flags);
+
+        tty_wakeup(tty);
+}
+
+
 /*
  * This routine is called when the serial port gets closed.  First, we
  * wait for the last remaining data to be sent.  Then, we unlink its
@@ -1013,9 +1034,7 @@ static void mxser_close(struct tty_struct *tty, struct file *filp)
         }
         mxser_shutdown(info);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
-
+        mxser_flush_buffer(tty);
         tty_ldisc_flush(tty);
 
         tty->closing = 0;
@@ -1142,26 +1161,6 @@ static int mxser_chars_in_buffer(struct tty_struct *tty)
         return info->xmit_cnt;
 }
 
-static void mxser_flush_buffer(struct tty_struct *tty)
-{
-        struct mxser_port *info = tty->driver_data;
-        char fcr;
-        unsigned long flags;
-
-
-        spin_lock_irqsave(&info->slock, flags);
-        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
-
-        fcr = inb(info->ioaddr + UART_FCR);
-        outb((fcr | UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT),
-                info->ioaddr + UART_FCR);
-        outb(fcr, info->ioaddr + UART_FCR);
-
-        spin_unlock_irqrestore(&info->slock, flags);
-
-        tty_wakeup(tty);
-}
-
 /*
  * ------------------------------------------------------------
  * friends of mxser_ioctl()
@@ -1992,6 +1991,7 @@ static void mxser_wait_until_sent(struct tty_struct *tty, int timeout)
                 timeout, char_time);
         printk("jiff=%lu...", jiffies);
 #endif
+        lock_kernel();
         while (!((lsr = inb(info->ioaddr + UART_LSR)) & UART_LSR_TEMT)) {
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
                 printk("lsr = %d (jiff=%lu)...", lsr, jiffies);
@@ -2003,6 +2003,7 @@ static void mxser_wait_until_sent(struct tty_struct *tty, int timeout)
                         break;
         }
         set_current_state(TASK_RUNNING);
+        unlock_kernel();
 
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
         printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
diff --git a/drivers/char/nozomi.c b/drivers/char/nozomi.c
index 6a6843a0a674..b55c933d5585 100644
--- a/drivers/char/nozomi.c
+++ b/drivers/char/nozomi.c
@@ -1724,6 +1724,8 @@ static int ntty_tiocmget(struct tty_struct *tty, struct file *file)
         const struct ctrl_dl *ctrl_dl = &port->ctrl_dl;
         const struct ctrl_ul *ctrl_ul = &port->ctrl_ul;
 
+        /* Note: these could change under us but it is not clear this
+           matters if so */
         return  (ctrl_ul->RTS ? TIOCM_RTS : 0) |
                 (ctrl_ul->DTR ? TIOCM_DTR : 0) |
                 (ctrl_dl->DCD ? TIOCM_CAR : 0) |
@@ -1849,16 +1851,6 @@ static void ntty_throttle(struct tty_struct *tty)
         spin_unlock_irqrestore(&dc->spin_mutex, flags);
 }
 
-/* just to discard single character writes */
-static void ntty_put_char(struct tty_struct *tty, unsigned char c)
-{
-        /*
-         * card does not react correct when we write single chars
-         * to the card, so we discard them
-         */
-        DBG2("PUT CHAR Function: %c", c);
-}
-
 /* Returns number of chars in buffer, called by tty layer */
 static s32 ntty_chars_in_buffer(struct tty_struct *tty)
 {
@@ -1892,7 +1884,6 @@ static const struct tty_operations tty_ops = {
         .unthrottle = ntty_unthrottle,
         .throttle = ntty_throttle,
         .chars_in_buffer = ntty_chars_in_buffer,
-        .put_char = ntty_put_char,
         .tiocmget = ntty_tiocmget,
         .tiocmset = ntty_tiocmset,
 };
diff --git a/drivers/char/pcmcia/synclink_cs.c b/drivers/char/pcmcia/synclink_cs.c
index 583356426dfb..45d8eb5de69f 100644
--- a/drivers/char/pcmcia/synclink_cs.c
+++ b/drivers/char/pcmcia/synclink_cs.c
@@ -503,20 +503,9 @@ static void* mgslpc_get_text_ptr(void)
  * The wrappers maintain line discipline references
  * while calling into the line discipline.
  *
- * ldisc_flush_buffer - flush line discipline receive buffers
  * ldisc_receive_buf  - pass receive data to line discipline
  */
 
-static void ldisc_flush_buffer(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);
-        }
-}
-
 static void ldisc_receive_buf(struct tty_struct *tty,
                               const __u8 *data, char *flags, int count)
 {
@@ -2467,10 +2456,9 @@ static void mgslpc_close(struct tty_struct *tty, struct file * filp)
         if (info->flags & ASYNC_INITIALIZED)
                 mgslpc_wait_until_sent(tty, info->timeout);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        mgslpc_flush_buffer(tty);
 
-        ldisc_flush_buffer(tty);
+        tty_ldisc_flush(tty);
 
         shutdown(info);
 
diff --git a/drivers/char/riscom8.c b/drivers/char/riscom8.c
index b56e0e04cb4a..a82c2a2d5e6c 100644
--- a/drivers/char/riscom8.c
+++ b/drivers/char/riscom8.c
@@ -1015,6 +1015,24 @@ static int rc_open(struct tty_struct * tty, struct file * filp)
         return 0;
 }
 
+static void rc_flush_buffer(struct tty_struct *tty)
+{
+        struct riscom_port *port = (struct riscom_port *)tty->driver_data;
+        unsigned long flags;
+
+        if (rc_paranoia_check(port, tty->name, "rc_flush_buffer"))
+                return;
+
+        spin_lock_irqsave(&riscom_lock, flags);
+
+        port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
+
+        spin_unlock_irqrestore(&riscom_lock, flags);
+
+        tty_wakeup(tty);
+}
+
+
 static void rc_close(struct tty_struct * tty, struct file * filp)
 {
         struct riscom_port *port = (struct riscom_port *) tty->driver_data;
@@ -1078,8 +1096,7 @@ static void rc_close(struct tty_struct * tty, struct file * filp)
                 }
         }
         rc_shutdown_port(bp, port);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        rc_flush_buffer(tty);
         tty_ldisc_flush(tty);
 
         tty->closing = 0;
@@ -1213,23 +1230,6 @@ static int rc_chars_in_buffer(struct tty_struct *tty)
         return port->xmit_cnt;
 }
 
-static void rc_flush_buffer(struct tty_struct *tty)
-{
-        struct riscom_port *port = (struct riscom_port *)tty->driver_data;
-        unsigned long flags;
-                                
-        if (rc_paranoia_check(port, tty->name, "rc_flush_buffer"))
-                return;
-
-        spin_lock_irqsave(&riscom_lock, flags);
-
-        port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
-
-        spin_unlock_irqrestore(&riscom_lock, flags);
-        
-        tty_wakeup(tty);
-}
-
 static int rc_tiocmget(struct tty_struct *tty, struct file *file)
 {
         struct riscom_port *port = (struct riscom_port *)tty->driver_data;
diff --git a/drivers/char/rocket.c b/drivers/char/rocket.c
index 32fe8dca24b6..00cfb6c7fd46 100644
--- a/drivers/char/rocket.c
+++ b/drivers/char/rocket.c
@@ -1585,6 +1585,7 @@ static void rp_wait_until_sent(struct tty_struct *tty, int timeout)
                jiffies);
         printk(KERN_INFO "cps=%d...\n", info->cps);
 #endif
+        lock_kernel();
         while (1) {
                 txcnt = sGetTxCnt(cp);
                 if (!txcnt) {
@@ -1612,6 +1613,7 @@ static void rp_wait_until_sent(struct tty_struct *tty, int timeout)
                         break;
         }
         __set_current_state(TASK_RUNNING);
+        unlock_kernel();
 #ifdef ROCKET_DEBUG_WAIT_UNTIL_SENT
         printk(KERN_INFO "txcnt = %d (jiff=%lu)...done\n", txcnt, jiffies);
 #endif
diff --git a/drivers/char/serial167.c b/drivers/char/serial167.c
index f62fb9360c3f..62d6f2e0fd18 100644
--- a/drivers/char/serial167.c
+++ b/drivers/char/serial167.c
@@ -1674,8 +1674,7 @@ static void cy_close(struct tty_struct *tty, struct file *filp)
         if (info->flags & ASYNC_INITIALIZED)
                 tty_wait_until_sent(tty, 3000); /* 30 seconds timeout */
         shutdown(info);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        cy_flush_buffer(tty);
         tty_ldisc_flush(tty);
         info->tty = NULL;
         if (info->blocked_open) {
diff --git a/drivers/char/specialix.c b/drivers/char/specialix.c
index 9f9a4bdc1b0e..075ad924dd04 100644
--- a/drivers/char/specialix.c
+++ b/drivers/char/specialix.c
@@ -1504,6 +1504,27 @@ static int sx_open(struct tty_struct * tty, struct file * filp)
         return 0;
 }
 
+static void sx_flush_buffer(struct tty_struct *tty)
+{
+        struct specialix_port *port = (struct specialix_port *)tty->driver_data;
+        unsigned long flags;
+        struct specialix_board  * bp;
+
+        func_enter();
+
+        if (sx_paranoia_check(port, tty->name, "sx_flush_buffer")) {
+                func_exit();
+                return;
+        }
+
+        bp = port_Board(port);
+        spin_lock_irqsave(&port->lock, flags);
+        port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
+        spin_unlock_irqrestore(&port->lock, flags);
+        tty_wakeup(tty);
+
+        func_exit();
+}
 
 static void sx_close(struct tty_struct * tty, struct file * filp)
 {
@@ -1597,8 +1618,7 @@ static void sx_close(struct tty_struct * tty, struct file * filp)
         }
 
         sx_shutdown_port(bp, port);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        sx_flush_buffer(tty);
         tty_ldisc_flush(tty);
         spin_lock_irqsave(&port->lock, flags);
         tty->closing = 0;
@@ -1770,28 +1790,6 @@ static int sx_chars_in_buffer(struct tty_struct *tty)
 }
 
 
-static void sx_flush_buffer(struct tty_struct *tty)
-{
-        struct specialix_port *port = (struct specialix_port *)tty->driver_data;
-        unsigned long flags;
-        struct specialix_board  * bp;
-
-        func_enter();
-
-        if (sx_paranoia_check(port, tty->name, "sx_flush_buffer")) {
-                func_exit();
-                return;
-        }
-
-        bp = port_Board(port);
-        spin_lock_irqsave(&port->lock, flags);
-        port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
-        spin_unlock_irqrestore(&port->lock, flags);
-        tty_wakeup(tty);
-
-        func_exit();
-}
-
 
 static int sx_tiocmget(struct tty_struct *tty, struct file *file)
 {
diff --git a/drivers/char/stallion.c b/drivers/char/stallion.c
index 983244ab1362..d17be10c5d21 100644
--- a/drivers/char/stallion.c
+++ b/drivers/char/stallion.c
@@ -875,6 +875,7 @@ static void stl_waituntilsent(struct tty_struct *tty, int timeout)
                 timeout = HZ;
         tend = jiffies + timeout;
 
+        lock_kernel();
         while (stl_datastate(portp)) {
                 if (signal_pending(current))
                         break;
@@ -882,6 +883,7 @@ static void stl_waituntilsent(struct tty_struct *tty, int timeout)
                 if (time_after_eq(jiffies, tend))
                         break;
         }
+        unlock_kernel();
 }
 
 /*****************************************************************************/
diff --git a/drivers/char/synclink.c b/drivers/char/synclink.c
index 1c9c440f59ce..dbbd998ae103 100644
--- a/drivers/char/synclink.c
+++ b/drivers/char/synclink.c
@@ -3157,8 +3157,7 @@ static void mgsl_close(struct tty_struct *tty, struct file * filp)
         if (info->flags & ASYNC_INITIALIZED)
                 mgsl_wait_until_sent(tty, info->timeout);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        mgsl_flush_buffer(tty);
 
         tty_ldisc_flush(tty);
                 
@@ -3221,7 +3220,8 @@ static void mgsl_wait_until_sent(struct tty_struct *tty, int timeout)
          * interval should also be less than the timeout.
          * Note: use tight timings here to satisfy the NIST-PCTS.
          */ 
-       
+
+        lock_kernel();
         if ( info->params.data_rate ) {
                 char_time = info->timeout/(32 * 5);
                 if (!char_time)
@@ -3251,6 +3251,7 @@ static void mgsl_wait_until_sent(struct tty_struct *tty, int timeout)
                                 break;
                 }
         }
+        unlock_kernel();
       
 exit:
         if (debug_level >= DEBUG_LEVEL_INFO)
diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 6473ae023466..1a11717b1adc 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -771,8 +771,7 @@ static void close(struct tty_struct *tty, struct file *filp)
 
         if (info->flags & ASYNC_INITIALIZED)
                 wait_until_sent(tty, info->timeout);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        flush_buffer(tty);
         tty_ldisc_flush(tty);
 
         shutdown(info);
@@ -967,6 +966,8 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
          * Note: use tight timings here to satisfy the NIST-PCTS.
          */
 
+        lock_kernel();
+
         if (info->params.data_rate) {
                 char_time = info->timeout/(32 * 5);
                 if (!char_time)
@@ -984,6 +985,7 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
                 if (timeout && time_after(jiffies, orig_jiffies + timeout))
                         break;
         }
+        unlock_kernel();
 
 exit:
         DBGINFO(("%s wait_until_sent exit\n", info->device_name));
diff --git a/drivers/char/synclinkmp.c b/drivers/char/synclinkmp.c
index b716a73a236f..2f1988c48ee3 100644
--- a/drivers/char/synclinkmp.c
+++ b/drivers/char/synclinkmp.c
@@ -862,8 +862,7 @@ static void close(struct tty_struct *tty, struct file *filp)
         if (info->flags & ASYNC_INITIALIZED)
                 wait_until_sent(tty, info->timeout);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        flush_buffer(tty);
 
         tty_ldisc_flush(tty);
 
@@ -1119,6 +1118,8 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
         if (sanity_check(info, tty->name, "wait_until_sent"))
                 return;
 
+        lock_kernel();
+
         if (!(info->flags & ASYNC_INITIALIZED))
                 goto exit;
 
@@ -1161,6 +1162,7 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
         }
 
 exit:
+        unlock_kernel();
         if (debug_level >= DEBUG_LEVEL_INFO)
                 printk("%s(%d):%s wait_until_sent() exit\n",
                          __FILE__,__LINE__, info->device_name );
@@ -1176,6 +1178,7 @@ static int write_room(struct tty_struct *tty)
         if (sanity_check(info, tty->name, "write_room"))
                 return 0;
 
+        lock_kernel();
         if (info->params.mode == MGSL_MODE_HDLC) {
                 ret = (info->tx_active) ? 0 : HDLC_MAX_FRAME_SIZE;
         } else {
@@ -1183,6 +1186,7 @@ static int write_room(struct tty_struct *tty)
                 if (ret < 0)
                         ret = 0;
         }
+        unlock_kernel();
 
         if (debug_level >= DEBUG_LEVEL_INFO)
                 printk("%s(%d):%s write_room()=%d\n",
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 35c7d2eb8b28..b1692afd797e 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1204,7 +1204,7 @@ EXPORT_SYMBOL_GPL(tty_find_polling_driver);
  *      not in the foreground, send a SIGTTOU.  If the signal is blocked or
  *      ignored, go ahead and perform the operation.  (POSIX 7.2)
  *
- *      Locking: ctrl_lock - FIXME: review this
+ *      Locking: ctrl_lock
  */
 
 int tty_check_change(struct tty_struct *tty)
diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index d769e43f73fb..8c4bf3e48d5b 100644
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -396,7 +396,7 @@ EXPORT_SYMBOL(tty_termios_hw_change);
 static void change_termios(struct tty_struct *tty, struct ktermios *new_termios)
 {
         int canon_change;
-        struct ktermios old_termios = *tty->termios;
+        struct ktermios old_termios;
         struct tty_ldisc *ld;
         unsigned long flags;
 
@@ -408,7 +408,7 @@ static void change_termios(struct tty_struct *tty, struct ktermios *new_termios)
         /* FIXME: we need to decide on some locking/ordering semantics
            for the set_termios notification eventually */
         mutex_lock(&tty->termios_mutex);
-
+        old_termios = *tty->termios;
         *tty->termios = *new_termios;
         unset_locked_termios(tty->termios, &old_termios, tty->termios_locked);
         canon_change = (old_termios.c_lflag ^ tty->termios->c_lflag) & ICANON;
@@ -480,7 +480,9 @@ static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
         if (retval)
                 return retval;
 
+        mutex_lock(&tty->termios_mutex);
         memcpy(&tmp_termios, tty->termios, sizeof(struct ktermios));
+        mutex_unlock(&tty->termios_mutex);
 
         if (opt & TERMIOS_TERMIO) {
                 if (user_termio_to_kernel_termios(&tmp_termios,
@@ -666,12 +668,14 @@ static int get_tchars(struct tty_struct *tty, struct tchars __user *tchars)
 {
         struct tchars tmp;
 
+        mutex_lock(&tty->termios_mutex);
         tmp.t_intrc = tty->termios->c_cc[VINTR];
         tmp.t_quitc = tty->termios->c_cc[VQUIT];
         tmp.t_startc = tty->termios->c_cc[VSTART];
         tmp.t_stopc = tty->termios->c_cc[VSTOP];
         tmp.t_eofc = tty->termios->c_cc[VEOF];
         tmp.t_brkc = tty->termios->c_cc[VEOL2]; /* what is brkc anyway? */
+        mutex_unlock(&tty->termios_mutex);
         return copy_to_user(tchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 }
 
@@ -681,12 +685,14 @@ static int set_tchars(struct tty_struct *tty, struct tchars __user *tchars)
 
         if (copy_from_user(&tmp, tchars, sizeof(tmp)))
                 return -EFAULT;
+        mutex_lock(&tty->termios_mutex);
         tty->termios->c_cc[VINTR] = tmp.t_intrc;
         tty->termios->c_cc[VQUIT] = tmp.t_quitc;
         tty->termios->c_cc[VSTART] = tmp.t_startc;
         tty->termios->c_cc[VSTOP] = tmp.t_stopc;
         tty->termios->c_cc[VEOF] = tmp.t_eofc;
         tty->termios->c_cc[VEOL2] = tmp.t_brkc; /* what is brkc anyway? */
+        mutex_unlock(&tty->termios_mutex);
         return 0;
 }
 #endif
@@ -696,6 +702,7 @@ static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
 {
         struct ltchars tmp;
 
+        mutex_lock(&tty->termios_mutex);
         tmp.t_suspc = tty->termios->c_cc[VSUSP];
         /* what is dsuspc anyway? */
         tmp.t_dsuspc = tty->termios->c_cc[VSUSP];
@@ -704,6 +711,7 @@ static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
         tmp.t_flushc = tty->termios->c_cc[VEOL2];
         tmp.t_werasc = tty->termios->c_cc[VWERASE];
         tmp.t_lnextc = tty->termios->c_cc[VLNEXT];
+        mutex_unlock(&tty->termios_mutex);
         return copy_to_user(ltchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 }
 
@@ -714,6 +722,7 @@ static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
         if (copy_from_user(&tmp, ltchars, sizeof(tmp)))
                 return -EFAULT;
 
+        mutex_lock(&tty->termios_mutex);
         tty->termios->c_cc[VSUSP] = tmp.t_suspc;
         /* what is dsuspc anyway? */
         tty->termios->c_cc[VEOL2] = tmp.t_dsuspc;
@@ -722,6 +731,7 @@ static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
         tty->termios->c_cc[VEOL2] = tmp.t_flushc;
         tty->termios->c_cc[VWERASE] = tmp.t_werasc;
         tty->termios->c_cc[VLNEXT] = tmp.t_lnextc;
+        mutex_unlock(&tty->termios_mutex);
         return 0;
 }
 #endif
diff --git a/drivers/isdn/i4l/isdn_tty.c b/drivers/isdn/i4l/isdn_tty.c
index a033f53209d5..1a2222cbb805 100644
--- a/drivers/isdn/i4l/isdn_tty.c
+++ b/drivers/isdn/i4l/isdn_tty.c
@@ -1708,9 +1708,7 @@ isdn_tty_close(struct tty_struct *tty, struct file *filp)
         }
         dev->modempoll--;
         isdn_tty_shutdown(info);
-        
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        isdn_tty_flush_buffer(tty);
         tty_ldisc_flush(tty);
         info->tty = NULL;
         info->ncarrier = 0;
diff --git a/drivers/serial/68328serial.c b/drivers/serial/68328serial.c
index 2b8a410e0959..5ce3e57bff0b 100644
--- a/drivers/serial/68328serial.c
+++ b/drivers/serial/68328serial.c
@@ -1017,18 +1017,6 @@ static int rs_ioctl(struct tty_struct *tty, struct file * file,
                         tty_wait_until_sent(tty, 0);
                         send_break(info, arg ? arg*(100) : 250);
                         return 0;
-                case TIOCGSOFTCAR:
-                        error = put_user(C_CLOCAL(tty) ? 1 : 0,
-                                    (unsigned long *) arg);
-                        if (error)
-                                return error;
-                        return 0;
-                case TIOCSSOFTCAR:
-                        get_user(arg, (unsigned long *) arg);
-                        tty->termios->c_cflag =
-                                ((tty->termios->c_cflag & ~CLOCAL) |
-                                 (arg ? CLOCAL : 0));
-                        return 0;
                 case TIOCGSERIAL:
                         if (access_ok(VERIFY_WRITE, (void *) arg,
                                                 sizeof(struct serial_struct)))
@@ -1061,9 +1049,6 @@ static void rs_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
 {
         struct m68k_serial *info = (struct m68k_serial *)tty->driver_data;
 
-        if (tty->termios->c_cflag == old_termios->c_cflag)
-                return;
-
         change_speed(info);
 
         if ((old_termios->c_cflag & CRTSCTS) &&
@@ -1140,8 +1125,7 @@ static void rs_close(struct tty_struct *tty, struct file * filp)
         uart->ustcnt &= ~(USTCNT_RXEN | USTCNT_RX_INTR_MASK);
 
         shutdown(info);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        rs_flush_buffer(tty);
                 
         tty_ldisc_flush(tty);
         tty->closing = 0;
diff --git a/drivers/serial/68360serial.c b/drivers/serial/68360serial.c
index 6f540107d0bb..f4f737bfa0a7 100644
--- a/drivers/serial/68360serial.c
+++ b/drivers/serial/68360serial.c
@@ -1436,18 +1436,6 @@ static int rs_360_ioctl(struct tty_struct *tty, struct file * file,
                                 return retval;
                         end_break(info);
                         return 0;
-                case TIOCGSOFTCAR:
-                        /* return put_user(C_CLOCAL(tty) ? 1 : 0, (int *) arg); */
-                        put_user(C_CLOCAL(tty) ? 1 : 0, (int *) arg);
-                        return 0;
-                case TIOCSSOFTCAR:
-                        error = get_user(arg, (unsigned int *) arg); 
-                        if (error)
-                                return error;
-                        tty->termios->c_cflag =
-                                ((tty->termios->c_cflag & ~CLOCAL) |
-                                 (arg ? CLOCAL : 0));
-                        return 0;
 #ifdef maybe
                 case TIOCSERGETLSR: /* Get line status register */
                         return get_lsr_info(info, (unsigned int *) arg);
@@ -1665,8 +1653,7 @@ static void rs_360_close(struct tty_struct *tty, struct file * filp)
                 rs_360_wait_until_sent(tty, info->timeout);
         }
         shutdown(info);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        rs_360_flush_buffer(tty);
         tty_ldisc_flush(tty);           
         tty->closing = 0;
         info->event = 0;
@@ -1717,6 +1704,7 @@ static void rs_360_wait_until_sent(struct tty_struct *tty, int timeout)
         printk("jiff=%lu...", jiffies);
 #endif
 
+        lock_kernel();
         /* We go through the loop at least once because we can't tell
          * exactly when the last character exits the shifter.  There can
          * be at least two characters waiting to be sent after the buffers
@@ -1745,6 +1733,7 @@ static void rs_360_wait_until_sent(struct tty_struct *tty, int timeout)
                         bdp--;
         } while (bdp->status & BD_SC_READY);
         current->state = TASK_RUNNING;
+        unlock_kernel();
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
         printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
 #endif
diff --git a/drivers/serial/crisv10.c b/drivers/serial/crisv10.c
index 88e7c1d5b919..8b9af73c1d59 100644
--- a/drivers/serial/crisv10.c
+++ b/drivers/serial/crisv10.c
@@ -3581,8 +3581,9 @@ rs_tiocmset(struct tty_struct *tty, struct file *file,
                 unsigned int set, unsigned int clear)
 {
         struct e100_serial *info = (struct e100_serial *)tty->driver_data;
+        unsigned long flags;
 
-        lock_kernel();
+        local_irq_save(flags);
 
         if (clear & TIOCM_RTS)
                 e100_rts(info, 0);
@@ -3604,7 +3605,7 @@ rs_tiocmset(struct tty_struct *tty, struct file *file,
         if (set & TIOCM_CD)
                 e100_cd_out(info, 1);
 
-        unlock_kernel();
+        local_irq_restore(flags);
         return 0;
 }
 
@@ -3613,8 +3614,10 @@ rs_tiocmget(struct tty_struct *tty, struct file *file)
 {
         struct e100_serial *info = (struct e100_serial *)tty->driver_data;
         unsigned int result;
+        unsigned long flags;
+
+        local_irq_save(flags);
 
-        lock_kernel();
         result =
                 (!E100_RTS_GET(info) ? TIOCM_RTS : 0)
                 | (!E100_DTR_GET(info) ? TIOCM_DTR : 0)
@@ -3623,7 +3626,7 @@ rs_tiocmget(struct tty_struct *tty, struct file *file)
                 | (!E100_CD_GET(info) ? TIOCM_CAR : 0)
                 | (!E100_CTS_GET(info) ? TIOCM_CTS : 0);
 
-        unlock_kernel();
+        local_irq_restore(flags);
 
 #ifdef SERIAL_DEBUG_IO
         printk(KERN_DEBUG "ser%i: modem state: %i 0x%08X\n",
@@ -3702,10 +3705,6 @@ rs_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
 {
         struct e100_serial *info = (struct e100_serial *)tty->driver_data;
 
-        if (tty->termios->c_cflag == old_termios->c_cflag &&
-            tty->termios->c_iflag == old_termios->c_iflag)
-                return;
-
         change_speed(info);
 
         /* Handle turning off CRTSCTS */
@@ -3808,10 +3807,8 @@ rs_close(struct tty_struct *tty, struct file * filp)
 #endif
 
         shutdown(info);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
-        if (tty->ldisc.flush_buffer)
-                tty->ldisc.flush_buffer(tty);
+        rs_flush_buffer(tty);
+        tty_ldisc_flush_buffer(tty);
         tty->closing = 0;
         info->event = 0;
         info->tty = 0;
@@ -3885,6 +3882,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
          * Check R_DMA_CHx_STATUS bit 0-6=number of available bytes in FIFO
          * R_DMA_CHx_HWSW bit 31-16=nbr of bytes left in DMA buffer (0=64k)
          */
+        lock_kernel();
         orig_jiffies = jiffies;
         while (info->xmit.head != info->xmit.tail || /* More in send queue */
                (*info->ostatusadr & 0x007f) ||  /* more in FIFO */
@@ -3901,6 +3899,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
                         curr_time_usec - info->last_tx_active_usec;
         }
         set_current_state(TASK_RUNNING);
+        unlock_kernel();
 }
 
 /*
diff --git a/drivers/serial/mcfserial.c b/drivers/serial/mcfserial.c
index ddd3aa50d4ad..aafa1704e1ab 100644
--- a/drivers/serial/mcfserial.c
+++ b/drivers/serial/mcfserial.c
@@ -1072,18 +1072,6 @@ static int mcfrs_ioctl(struct tty_struct *tty, struct file * file,
                         tty_wait_until_sent(tty, 0);
                         send_break(info, arg ? arg*(HZ/10) : HZ/4);
                         return 0;
-                case TIOCGSOFTCAR:
-                        error = put_user(C_CLOCAL(tty) ? 1 : 0,
-                                    (unsigned long *) arg);
-                        if (error)
-                                return error;
-                        return 0;
-                case TIOCSSOFTCAR:
-                        get_user(arg, (unsigned long *) arg);
-                        tty->termios->c_cflag =
-                                ((tty->termios->c_cflag & ~CLOCAL) |
-                                 (arg ? CLOCAL : 0));
-                        return 0;
                 case TIOCGSERIAL:
                         if (access_ok(VERIFY_WRITE, (void *) arg,
                                                 sizeof(struct serial_struct)))
@@ -1222,8 +1210,7 @@ static void mcfrs_close(struct tty_struct *tty, struct file * filp)
         } else
 #endif
         shutdown(info);
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer(tty);
+        mcfrs_flush_buffer(tty);
         tty_ldisc_flush(tty);
         
         tty->closing = 0;
@@ -1276,6 +1263,8 @@ mcfrs_wait_until_sent(struct tty_struct *tty, int timeout)
          * Note: we have to use pretty tight timings here to satisfy
          * the NIST-PCTS.
          */
+        lock_kernel();
+
         fifo_time = (MCF5272_FIFO_SIZE * HZ * 10) / info->baud;
         char_time = fifo_time / 5;
         if (char_time == 0)
@@ -1312,6 +1301,7 @@ mcfrs_wait_until_sent(struct tty_struct *tty, int timeout)
                 if (timeout && time_after(jiffies, orig_jiffies + timeout))
                         break;
         }
+        unlock_kernel();
 #else
         /*
          * For the other coldfire models, assume all data has been sent
diff --git a/drivers/serial/netx-serial.c b/drivers/serial/netx-serial.c
index 3123ffeac8ad..81ac9bb4f39b 100644
--- a/drivers/serial/netx-serial.c
+++ b/drivers/serial/netx-serial.c
@@ -287,6 +287,7 @@ static void netx_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
         unsigned int val;
 
+        /* FIXME: Locking needed ? */
         if (mctrl & TIOCM_RTS) {
                 val = readl(port->membase + UART_RTS_CR);
                 writel(val | RTS_CR_RTS, port->membase + UART_RTS_CR);