synclink: reworking locking a bit

Use the port mutex and port lock to fix the various races. The locking
still isn't totally consistent but its better than before. Wants switching
to the port helpers.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 1 deletions

diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 3c7ac6a3ff80..5a602eb7cd2d 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -675,12 +675,14 @@ static int open(struct tty_struct *tty, struct file *filp)
                 goto cleanup;
         }
 
+        mutex_lock(&info->port.mutex);
         info->port.tty->low_latency = (info->port.flags & ASYNC_LOW_LATENCY) ? 1 : 0;
 
         spin_lock_irqsave(&info->netlock, flags);
         if (info->netcount) {
                 retval = -EBUSY;
                 spin_unlock_irqrestore(&info->netlock, flags);
+                mutex_unlock(&info->port.mutex);
                 goto cleanup;
         }
         info->port.count++;
@@ -692,7 +694,7 @@ static int open(struct tty_struct *tty, struct file *filp)
                 if (retval < 0)
                         goto cleanup;
         }
-
+        mutex_unlock(&info->port.mutex);
         retval = block_til_ready(tty, filp, info);
         if (retval) {
                 DBGINFO(("%s block_til_ready rc=%d\n", info->device_name, retval));
@@ -724,12 +726,14 @@ static void close(struct tty_struct *tty, struct file *filp)
         if (tty_port_close_start(&info->port, tty, filp) == 0)
                 goto cleanup;
 
+        mutex_lock(&info->port.mutex);
         if (info->port.flags & ASYNC_INITIALIZED)
                 wait_until_sent(tty, info->timeout);
         flush_buffer(tty);
         tty_ldisc_flush(tty);
 
         shutdown(info);
+        mutex_unlock(&info->port.mutex);
 
         tty_port_close_end(&info->port, tty);
         info->port.tty = NULL;
@@ -740,17 +744,23 @@ cleanup:
 static void hangup(struct tty_struct *tty)
 {
         struct slgt_info *info = tty->driver_data;
+        unsigned long flags;
 
         if (sanity_check(info, tty->name, "hangup"))
                 return;
         DBGINFO(("%s hangup\n", info->device_name));
 
         flush_buffer(tty);
+
+        mutex_lock(&info->port.mutex);
         shutdown(info);
 
+        spin_lock_irqsave(&info->port.lock, flags);
         info->port.count = 0;
         info->port.flags &= ~ASYNC_NORMAL_ACTIVE;
         info->port.tty = NULL;
+        spin_unlock_irqrestore(&info->port.lock, flags);
+        mutex_unlock(&info->port.mutex);
 
         wake_up_interruptible(&info->port.open_wait);
 }