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| 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 /Documentation | |
| 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 'Documentation')
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index ce1fa22aa70b..08d34e11bc54 100644 --- a/Documentation/watchdog/watchdog-kernel-api.txt +++ b/Documentation/watchdog/watchdog-kernel-api.txt @@ -50,6 +50,7 @@ struct watchdog_device { unsigned int min_timeout; unsigned int max_timeout; void *driver_data; + struct mutex lock; unsigned long status; }; @@ -74,6 +75,7 @@ It contains following fields: * driver_data: a pointer to the drivers private data of a watchdog device. This data should only be accessed via the watchdog_set_drvdata and watchdog_get_drvdata routines. +* lock: Mutex for WatchDog Timer Driver Core internal use only. * status: this field contains a number of status bits that give extra information about the status of the device (Like: is the watchdog timer running/active, is the nowayout bit set, is the device opened via |