Commit 6b55fc63 authored Oct 02, 2014 by Peter Zijlstra Committed by Ingo Molnar Nov 04, 2014

audit, sched/wait: Fixup kauditd_thread() wait loop



The kauditd_thread wait loop is a bit iffy; it has a number of problems:

 - calls try_to_freeze() before schedule(); you typically want the
   thread to re-evaluate the sleep condition when unfreezing, also
   freeze_task() issues a wakeup.

 - it unconditionally does the {add,remove}_wait_queue(), even when the
   sleep condition is false.

Use wait_event_freezable() that does the right thing.

Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: oleg@redhat.com
Cc: Eric Paris <eparis@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141002102251.GA6324@worktop.programming.kicks-ass.net


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 5d4d5658

kernel/audit.c

+1 −10

Original line number	Diff line number	Diff line
		@@ -499,7 +499,6 @@ static int kauditd_thread(void *dummy)
		set_freezable();
		while (!kthread_should_stop()) {
		struct sk_buff *skb;
		DECLARE_WAITQUEUE(wait, current);

		flush_hold_queue();

		@@ -514,16 +513,8 @@ static int kauditd_thread(void *dummy)
		audit_printk_skb(skb);
		continue;
		}
		set_current_state(TASK_INTERRUPTIBLE);
		add_wait_queue(&kauditd_wait, &wait);

		if (!skb_queue_len(&audit_skb_queue)) {
		try_to_freeze();
		schedule();
		}

		__set_current_state(TASK_RUNNING);
		remove_wait_queue(&kauditd_wait, &wait);
		wait_event_freezable(kauditd_wait, skb_queue_len(&audit_skb_queue));
		}
		return 0;
		}