Messages in this thread Patch in this message | | | Date | Wed, 05 Aug 2009 15:04:12 -0700 | From | Darren Hart <> | Subject | [PATCH 2/2][RT] Avoid deadlock in rt_mutex_start_proxy_lock() |
| |
In the event of a lock steal or owner died, rt_mutex_start_proxy_lock() will give the rt_mutex to the waiting task, but it fails to release the wait_lock. This leads to subsequent deadlocks when other tasks try to acquire the rt_mutex.
I also removed a few extra blank lines that really spaced this routine out. I must have been high on the \n when I wrote this originally...
Note: this is the -rt version, I'll send another for mainline.
Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@elte.hu> CC: Dinakar Guniguntala <dino@in.ibm.com> CC: John Stultz <johnstul@us.ibm.com> CC: John Kacur <jkacur@redhat.com>
Index: 2.6.31-rc4-rt1/kernel/rtmutex.c =================================================================== --- 2.6.31-rc4-rt1.orig/kernel/rtmutex.c 2009-08-05 10:29:39.000000000 -0700 +++ 2.6.31-rc4-rt1/kernel/rtmutex.c 2009-08-05 11:10:22.000000000 -0700 @@ -1517,9 +1517,8 @@ int rt_mutex_start_proxy_lock(struct rt_ try_to_steal_lock(lock, task, STEAL_NORMAL)) { /* We got the lock for task. */ debug_rt_mutex_lock(lock); - rt_mutex_set_owner(lock, task, 0); - + atomic_spin_unlock_irqrestore(&lock->wait_lock, flags); rt_mutex_deadlock_account_lock(lock, task); return 1; } @@ -1527,7 +1526,6 @@ int rt_mutex_start_proxy_lock(struct rt_ ret = task_blocks_on_rt_mutex(lock, waiter, task, detect_deadlock, flags); - if (ret && !waiter->task) { /* * Reset the return value. We might have -- Darren Hart IBM Linux Technology Center Real-Time Linux Team
| |