softlockup: fix task state setting

kthread_stop() can be called when a 'watchdog' thread is executing after kthread_should_stop() but before set_task_state(TASK_INTERRUPTIBLE). Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>

softlockup: fix task state setting
kthread_stop() can be called when a 'watchdog' thread is executing after kthread_should_stop() but before set_task_state(TASK_INTERRUPTIBLE). Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Dmitry Adamushko · Ingo Molnar
1 parent 2232c2d8e0
Showing 1 changed file with 7 additions and 6 deletions Side-by-side Diff
kernel/softlockup.c
@@ -216,26 +216,27 @@
 	/* initialize timestamp */
 	touch_softlockup_watchdog();
  
+	set_current_state(TASK_INTERRUPTIBLE);
 	/*
 	 * Run briefly once per second to reset the softlockup timestamp.
 	 * If this gets delayed for more than 60 seconds then the
 	 * debug-printout triggers in softlockup_tick().
 	 */
 	while (!kthread_should_stop()) {
-		set_current_state(TASK_INTERRUPTIBLE);
 		touch_softlockup_watchdog();
 		schedule();
  
 		if (kthread_should_stop())
 			break;
  
-		if (this_cpu != check_cpu)
-			continue;
+		if (this_cpu == check_cpu) {
+			if (sysctl_hung_task_timeout_secs)
+				check_hung_uninterruptible_tasks(this_cpu);
+		}
  
-		if (sysctl_hung_task_timeout_secs)
-			check_hung_uninterruptible_tasks(this_cpu);
-
+		set_current_state(TASK_INTERRUPTIBLE);
 	}
+	__set_current_state(TASK_RUNNING);
  
 	return 0;
 }
...	...	@@ -216,26 +216,27 @@
216	216	/* initialize timestamp */
217	217	touch_softlockup_watchdog();
218	218
	219	+ set_current_state(TASK_INTERRUPTIBLE);
219	220	/*
220	221	* Run briefly once per second to reset the softlockup timestamp.
221	222	* If this gets delayed for more than 60 seconds then the
222	223	* debug-printout triggers in softlockup_tick().
223	224	*/
224	225	while (!kthread_should_stop()) {
225		- set_current_state(TASK_INTERRUPTIBLE);
226	226	touch_softlockup_watchdog();
227	227	schedule();
228	228
229	229	if (kthread_should_stop())
230	230	break;
231	231
232		- if (this_cpu != check_cpu)
233		- continue;
	232	+ if (this_cpu == check_cpu) {
	233	+ if (sysctl_hung_task_timeout_secs)
	234	+ check_hung_uninterruptible_tasks(this_cpu);
	235	+ }
234	236
235		- if (sysctl_hung_task_timeout_secs)
236		- check_hung_uninterruptible_tasks(this_cpu);
237		-
	237	+ set_current_state(TASK_INTERRUPTIBLE);
238	238	}
	239	+ __set_current_state(TASK_RUNNING);
239	240
240	241	return 0;
241	242	}