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Subject[PATCH 10/31] synclink: reworking locking a bit
Date
From: Alan Cox <alan@linux.intel.com>

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>
---
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);
}
--
1.7.0.4


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