linux-kernel - [PATCH 14/14] synclink: reworking locking a bit

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Date:	Thu, 01 Apr 2010 17:07:18 +0100
From:	Alan Cox <alan@...ux.intel.com>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH 14/14] 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@...ux.intel.com>
---

 drivers/char/synclink_gt.c |   12 +++++++++++-
 drivers/char/synclinkmp.c  |    9 ++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)


diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index d0f81f5..c56b70a 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);
 }
diff --git a/drivers/char/synclinkmp.c b/drivers/char/synclinkmp.c
index 8da976b..cfa581e 100644
--- a/drivers/char/synclinkmp.c
+++ b/drivers/char/synclinkmp.c
@@ -812,13 +812,15 @@ 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;
@@ -834,6 +836,7 @@ cleanup:
 static void hangup(struct tty_struct *tty)
 {
 	SLMP_INFO *info = tty->driver_data;
+	unsigned long flags;
 
 	if (debug_level >= DEBUG_LEVEL_INFO)
 		printk("%s(%d):%s hangup()\n",
@@ -842,12 +845,16 @@ static void hangup(struct tty_struct *tty)
 	if (sanity_check(info, tty->name, "hangup"))
 		return;
 
+	mutex_lock(&info->port.mutex);		
 	flush_buffer(tty);
 	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);
 }

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