diff options
author | Hans de Goede <hdegoede@redhat.com> | 2012-05-22 11:40:26 +0200 |
---|---|---|
committer | Wim Van Sebroeck <wim@iguana.be> | 2012-05-30 07:55:23 +0200 |
commit | f4e9c82f64b524314a390b13d3ba7d483f09258f (patch) | |
tree | 82d688ae7782234dc01c6a340596bac21531aae4 /drivers/watchdog/watchdog_dev.c | |
parent | watchdog: watchdog_dev: Rewrite wrapper code (diff) | |
download | linux-f4e9c82f64b524314a390b13d3ba7d483f09258f.tar.xz linux-f4e9c82f64b524314a390b13d3ba7d483f09258f.zip |
watchdog: Add Locking support
This patch fixes some potential multithreading issues, despite only
allowing one process to open the /dev/watchdog device, we can still get
called multiple times at the same time, since a program could be using thread,
or could share the fd after a fork.
This causes 2 potential problems:
1) watchdog_start / open do an unlocked test_n_set / test_n_clear,
if these 2 race, the watchdog could be stopped while the active
bit indicates it is running or visa versa.
2) Most watchdog_dev drivers probably assume that only one
watchdog-op will get called at a time, this is not necessary
true atm.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Diffstat (limited to 'drivers/watchdog/watchdog_dev.c')
-rw-r--r-- | drivers/watchdog/watchdog_dev.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index 76d2572fed25..4d295d229a07 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -63,6 +63,8 @@ static int watchdog_ping(struct watchdog_device *wddev) { int err = 0; + mutex_lock(&wddev->lock); + if (!watchdog_active(wddev)) goto out_ping; @@ -72,6 +74,7 @@ static int watchdog_ping(struct watchdog_device *wddev) err = wddev->ops->start(wddev); /* restart watchdog */ out_ping: + mutex_unlock(&wddev->lock); return err; } @@ -88,6 +91,8 @@ static int watchdog_start(struct watchdog_device *wddev) { int err = 0; + mutex_lock(&wddev->lock); + if (watchdog_active(wddev)) goto out_start; @@ -96,6 +101,7 @@ static int watchdog_start(struct watchdog_device *wddev) set_bit(WDOG_ACTIVE, &wddev->status); out_start: + mutex_unlock(&wddev->lock); return err; } @@ -113,6 +119,8 @@ static int watchdog_stop(struct watchdog_device *wddev) { int err = 0; + mutex_lock(&wddev->lock); + if (!watchdog_active(wddev)) goto out_stop; @@ -127,6 +135,7 @@ static int watchdog_stop(struct watchdog_device *wddev) clear_bit(WDOG_ACTIVE, &wddev->status); out_stop: + mutex_unlock(&wddev->lock); return err; } @@ -147,8 +156,11 @@ static int watchdog_get_status(struct watchdog_device *wddev, if (!wddev->ops->status) return -EOPNOTSUPP; + mutex_lock(&wddev->lock); + *status = wddev->ops->status(wddev); + mutex_unlock(&wddev->lock); return err; } @@ -171,8 +183,11 @@ static int watchdog_set_timeout(struct watchdog_device *wddev, (timeout < wddev->min_timeout || timeout > wddev->max_timeout)) return -EINVAL; + mutex_lock(&wddev->lock); + err = wddev->ops->set_timeout(wddev, timeout); + mutex_unlock(&wddev->lock); return err; } @@ -193,8 +208,11 @@ static int watchdog_get_timeleft(struct watchdog_device *wddev, if (!wddev->ops->get_timeleft) return -EOPNOTSUPP; + mutex_lock(&wddev->lock); + *timeleft = wddev->ops->get_timeleft(wddev); + mutex_unlock(&wddev->lock); return err; } @@ -213,8 +231,11 @@ static int watchdog_ioctl_op(struct watchdog_device *wddev, unsigned int cmd, if (!wddev->ops->ioctl) return -ENOIOCTLCMD; + mutex_lock(&wddev->lock); + err = wddev->ops->ioctl(wddev, cmd, arg); + mutex_unlock(&wddev->lock); return err; } |