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watchdog: add CONFIG_WATCHDOG_NOWAYOUT support to PowerPC Book-E watchdog driver

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Normally, the watchdog is disabled when dev/watchdog is closed, but if
CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the watchdog should
remain enabled.  So we should disable it only if CONFIG_WATCHDOG_NOWAYOUT is
not defined.

Also ensure that /dev/watchdog is only opened by one process at a time.  That
way, a second process can't accidentally disable the watchdog while the first
process has it open.  There shouldn't be any need for more than one process to
open /dev/watchdog anyway.

Signed-off-by: Timur Tabi <timur@freescale.com>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Timur Tabi 2010-12-03 10:51:43 -06:00 committed by Wim Van Sebroeck
parent a787e71068
commit 5d63c13415
1 changed files with 16 additions and 0 deletions
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16
drivers/watchdog/booke_wdt.c
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@ -193,8 +193,15 @@ static long booke_wdt_ioctl(struct file *file,
return 0;
}
/* wdt_is_active stores wether or not the /dev/watchdog device is opened */
static unsigned long wdt_is_active;
static int booke_wdt_open(struct inode *inode, struct file *file)
{
/* /dev/watchdog can only be opened once */
if (test_and_set_bit(0, &wdt_is_active))
return -EBUSY;
spin_lock(&booke_wdt_lock);
if (booke_wdt_enabled == 0) {
booke_wdt_enabled = 1;
@ -210,8 +217,17 @@ static int booke_wdt_open(struct inode *inode, struct file *file)
static int booke_wdt_release(struct inode *inode, struct file *file)
{
#ifndef CONFIG_WATCHDOG_NOWAYOUT
/* Normally, the watchdog is disabled when /dev/watchdog is closed, but
* if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the
* watchdog should remain enabled. So we disable it only if
* CONFIG_WATCHDOG_NOWAYOUT is not defined.
*/
on_each_cpu(__booke_wdt_disable, NULL, 0);
booke_wdt_enabled = 0;
#endif
clear_bit(0, &wdt_is_active);
return 0;
}