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authorHans de Goede <hdegoede@redhat.com>2012-05-22 11:40:26 +0200
committerWim Van Sebroeck <wim@iguana.be>2012-05-30 07:55:23 +0200
commitf4e9c82f64b524314a390b13d3ba7d483f09258f (patch)
tree82d688ae7782234dc01c6a340596bac21531aae4 /Documentation/watchdog
parent7a87982420e5e126bfefeb42232d1fd92052794e (diff)
downloadlinux-f4e9c82f64b524314a390b13d3ba7d483f09258f.tar.gz
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/watchdog')
-rw-r--r--Documentation/watchdog/watchdog-kernel-api.txt2
1 files changed, 2 insertions, 0 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index ce1fa22aa70..08d34e11bc5 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