Commit 073107b3 authored by Sangmoon Kim's avatar Sangmoon Kim Committed by Tejun Heo
Browse files

workqueue: add cmdline parameter workqueue.panic_on_stall 



When we want to debug the workqueue stall, we can immediately make
a panic to get the information we want.

In some systems, it may be necessary to quickly reboot the system to
escape from a workqueue lockup situation. In this case, we can control
the number of stall detections to generate panic.

workqueue.panic_on_stall sets the number times of the stall to trigger
panic. 0 disables the panic on stall.

Signed-off-by: default avatarSangmoon Kim <sangmoon.kim@samsung.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 8400291e

kernel/workqueue.c

+16 −0
Original line number Diff line number Diff line
@@ -7398,6 +7398,9 @@ static struct timer_list wq_watchdog_timer; 
static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;

static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;



static unsigned int wq_panic_on_stall;

module_param_named(panic_on_stall, wq_panic_on_stall, uint, 0644);



/*

 * Show workers that might prevent the processing of pending work items.

 * The only candidates are CPU-bound workers in the running state.
@@ -7449,6 +7452,16 @@ static void show_cpu_pools_hogs(void) 
	rcu_read_unlock();

}



static void panic_on_wq_watchdog(void)

{

	static unsigned int wq_stall;



	if (wq_panic_on_stall) {

		wq_stall++;

		BUG_ON(wq_stall >= wq_panic_on_stall);

	}

}



static void wq_watchdog_reset_touched(void)

{

	int cpu;
@@ -7521,6 +7534,9 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) 
	if (cpu_pool_stall)

		show_cpu_pools_hogs();



	if (lockup_detected)

		panic_on_wq_watchdog();



	wq_watchdog_reset_touched();

	mod_timer(&wq_watchdog_timer, jiffies + thresh);

}