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authorLi RongQing <roy.qing.li@gmail.com>2015-12-17 21:30:02 +0800
committerWim Van Sebroeck <wim@iguana.be>2015-12-27 21:02:21 +0100
commit5889f06bd31d542766046faa6b17d957c08e1484 (patch)
tree37e0bec23c48aa457d3ea7d23dceb0effb626c13
parent8d2fa17151ea33a98b5f70839fd2ffa3bce51de5 (diff)
watchdog: refuse to unload softdog module when its timer is running
the softdog has static variables which are accessed if its timer is still running after the driver is unloaded. and lead to crash: $modprobe softdog $echo 1 >/dev/watchdog $modprobe -r softdog CPU 20 Unable to handle kernel paging request at virtual address Oops[#1]: CPU: 20 PID: 0 Comm: swapper/20 Not tainted 4.1.13-WR8.0.0.0_standard ... Modules linked in: [last unloaded: softdog] .... Call Trace: [<ffffffff801e142c>] cascade+0x34/0xb0 [<ffffffff801e1964>] run_timer_softirq+0x30c/0x368 [<ffffffff80181044>] __do_softirq+0x1ec/0x418 [<ffffffff801815d0>] irq_exit+0x90/0x98 [<ffffffff8010749c>] plat_irq_dispatch+0xa4/0x140 [<ffffffff80152740>] ret_from_irq+0x0/0x4 [<ffffffff801529e0>] __r4k_wait+0x20/0x40 [<ffffffff801c2278>] cpu_startup_entry+0x2a0/0x368 [<ffffffff8015fa64>] start_secondary+0x444/0x4d8 add the module ref when timer is running to avoid to unload the softdog module Signed-off-by: Li RongQing <roy.qing.li@gmail.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
-rw-r--r--drivers/watchdog/softdog.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/watchdog/softdog.c b/drivers/watchdog/softdog.c
index fe1e15137bf6..99a06f9e3930 100644
--- a/drivers/watchdog/softdog.c
+++ b/drivers/watchdog/softdog.c
@@ -86,6 +86,7 @@ static struct timer_list watchdog_ticktock =
static void watchdog_fire(unsigned long data)
{
+ module_put(THIS_MODULE);
if (soft_noboot)
pr_crit("Triggered - Reboot ignored\n");
else if (soft_panic) {
@@ -104,13 +105,16 @@ static void watchdog_fire(unsigned long data)
static int softdog_ping(struct watchdog_device *w)
{
- mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ));
+ if (!mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ)))
+ __module_get(THIS_MODULE);
return 0;
}
static int softdog_stop(struct watchdog_device *w)
{
- del_timer(&watchdog_ticktock);
+ if (del_timer(&watchdog_ticktock))
+ module_put(THIS_MODULE);
+
return 0;
}