Commit-ID:  6b55fc63f46ba299f3d84013e9232be4bd259eab
Gitweb:     http://git.kernel.org/tip/6b55fc63f46ba299f3d84013e9232be4bd259eab
Author:     Peter Zijlstra <pet...@infradead.org>
AuthorDate: Thu, 2 Oct 2014 12:22:51 +0200
Committer:  Ingo Molnar <mi...@kernel.org>
CommitDate: Tue, 4 Nov 2014 07:17:47 +0100

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 <umgwanakikb...@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Eric Paris <epa...@redhat.com>
Cc: o...@redhat.com
Cc: Eric Paris <epa...@redhat.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Link: 
http://lkml.kernel.org/r/20141002102251.ga6...@worktop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
 kernel/audit.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index 80983df..32bfc43 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -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;
 }
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