TTY: srmcons, convert to use tty_port

This is needed because the tty buffer will become a tty_port member
later. That will help us to wipe out most of the races and checks for
the tty pointer in hot paths.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 17 insertions, 15 deletions

diff --git a/arch/alpha/kernel/srmcons.c b/arch/alpha/kernel/srmcons.c
index 2c89ce5c9ab6..3ea809430eda 100644
--- a/arch/alpha/kernel/srmcons.c
+++ b/arch/alpha/kernel/srmcons.c
@@ -30,9 +30,8 @@ static int srm_is_registered_console = 0;
 #define MAX_SRM_CONSOLE_DEVICES 1       /* only support 1 console device */
 
 struct srmcons_private {
-        struct tty_struct *tty;
+        struct tty_port port;
         struct timer_list timer;
-        spinlock_t lock;
 } srmcons_singleton;
 
 typedef union _srmcons_result {
@@ -68,20 +67,21 @@ static void
 srmcons_receive_chars(unsigned long data)
 {
         struct srmcons_private *srmconsp = (struct srmcons_private *)data;
+        struct tty_port *port = &srmconsp->port;
         unsigned long flags;
         int incr = 10;
 
         local_irq_save(flags);
         if (spin_trylock(&srmcons_callback_lock)) {
-                if (!srmcons_do_receive_chars(srmconsp->tty))
+                if (!srmcons_do_receive_chars(port->tty))
                         incr = 100;
                 spin_unlock(&srmcons_callback_lock);
         } 
 
-        spin_lock(&srmconsp->lock);
-        if (srmconsp->tty)
+        spin_lock(&port->lock);
+        if (port->tty)
                 mod_timer(&srmconsp->timer, jiffies + incr);
-        spin_unlock(&srmconsp->lock);
+        spin_unlock(&port->lock);
 
         local_irq_restore(flags);
 }
@@ -157,18 +157,19 @@ static int
 srmcons_open(struct tty_struct *tty, struct file *filp)
 {
         struct srmcons_private *srmconsp = &srmcons_singleton;
+        struct tty_port *port = &srmconsp->port;
         unsigned long flags;
 
-        spin_lock_irqsave(&srmconsp->lock, flags);
+        spin_lock_irqsave(&port->lock, flags);
 
-        if (!srmconsp->tty) {
+        if (!port->tty) {
                 tty->driver_data = srmconsp;
-
-                srmconsp->tty = tty;
+                tty->port = port;
+                port->tty = tty; /* XXX proper refcounting */
                 mod_timer(&srmconsp->timer, jiffies + 10);
         }
 
-        spin_unlock_irqrestore(&srmconsp->lock, flags);
+        spin_unlock_irqrestore(&port->lock, flags);
 
         return 0;
 }
@@ -177,16 +178,17 @@ static void
 srmcons_close(struct tty_struct *tty, struct file *filp)
 {
         struct srmcons_private *srmconsp = tty->driver_data;
+        struct tty_port *port = &srmconsp->port;
         unsigned long flags;
 
-        spin_lock_irqsave(&srmconsp->lock, flags);
+        spin_lock_irqsave(&port->lock, flags);
 
         if (tty->count == 1) {
-                srmconsp->tty = NULL;
+                port->tty = NULL;
                 del_timer(&srmconsp->timer);
         }
 
-        spin_unlock_irqrestore(&srmconsp->lock, flags);
+        spin_unlock_irqrestore(&port->lock, flags);
 }
 
 
@@ -203,7 +205,7 @@ static const struct tty_operations srmcons_ops = {
 static int __init
 srmcons_init(void)
 {
-        spin_lock_init(&srmcons_singleton.lock);
+        tty_port_init(&srmcons_singleton.port);
         setup_timer(&srmcons_singleton.timer, srmcons_receive_chars,
                         (unsigned long)&srmcons_singleton);
         if (srm_is_registered_console) {