tree 6e5f8ee1053e7add2ec1890b594dc4086ae39f09
parent 93642ecd463df30d032da8ac37c2676cee4ad876
author Chuck Ebbert <[EMAIL PROTECTED]> Fri, 19 Aug 2005 14:14:07 +0200
committer Wim Van Sebroeck <[EMAIL PROTECTED]> Sat, 03 Sep 2005 13:59:46 +0200
[WATCHDOG] softdog-timer-running-oops.patch
The softdog watchdog timer has a bug that can create an oops:
1. Load the module without the nowayout option.
2. Open the driver and close it without writing 'V' before close.
3. Unload the module. The timer will continue to run...
4. Oops happens when timer fires.
Reported Sun, 10 Oct 2004, by Michael Schierl <[EMAIL PROTECTED]>
Fix is easy: always take a reference on the module on open.
Release it only when the device is closed and no timer is running.
Tested on 2.6.13-rc6 using the soft_noboot option. While the
timer is running and the device is closed, the module use count
stays at 1. After the timer fires, it drops to 0. Repeatedly
opening and closing the driver caused no problems. Please apply.
Signed-off-by: Chuck Ebbert <[EMAIL PROTECTED]>
Signed-off-by: Wim Van Sebroeck <[EMAIL PROTECTED]>
drivers/char/watchdog/softdog.c | 13 +++++++++----
1 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/char/watchdog/softdog.c b/drivers/char/watchdog/softdog.c
--- a/drivers/char/watchdog/softdog.c
+++ b/drivers/char/watchdog/softdog.c
@@ -77,7 +77,7 @@ static void watchdog_fire(unsigned long)
static struct timer_list watchdog_ticktock =
TIMER_INITIALIZER(watchdog_fire, 0, 0);
-static unsigned long timer_alive;
+static unsigned long driver_open, orphan_timer;
static char expect_close;
@@ -87,6 +87,9 @@ static char expect_close;
static void watchdog_fire(unsigned long data)
{
+ if (test_and_clear_bit(0, &orphan_timer))
+ module_put(THIS_MODULE);
+
if (soft_noboot)
printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
else
@@ -128,9 +131,9 @@ static int softdog_set_heartbeat(int t)
static int softdog_open(struct inode *inode, struct file *file)
{
- if(test_and_set_bit(0, &timer_alive))
+ if (test_and_set_bit(0, &driver_open))
return -EBUSY;
- if (nowayout)
+ if (!test_and_clear_bit(0, &orphan_timer))
__module_get(THIS_MODULE);
/*
* Activate timer
@@ -147,11 +150,13 @@ static int softdog_release(struct inode
*/
if (expect_close == 42) {
softdog_stop();
+ module_put(THIS_MODULE);
} else {
printk(KERN_CRIT PFX "Unexpected close, not stopping
watchdog!\n");
+ set_bit(0, &orphan_timer);
softdog_keepalive();
}
- clear_bit(0, &timer_alive);
+ clear_bit(0, &driver_open);
expect_close = 0;
return 0;
}
-
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