Messages in this thread Patch in this message | | | Date | Wed, 05 Aug 2009 12:05:21 -0700 | From | Darren Hart <> | Subject | [tip/urgent] Avoid deadlock in rt_mutex_start_proxy_lock() |
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From: Darren Hart <dvhltc@us.ibm.com>
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 mainline version, a separate patch was sent for [RT]
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> ---
kernel/rtmutex.c | 4 +--- 1 files changed, 1 insertions(+), 3 deletions(-)
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index fec77e7..0f2b9bb 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c @@ -1039,16 +1039,14 @@ int rt_mutex_start_proxy_lock(struct rt_mutex *lock, if (!rt_mutex_owner(lock) || try_to_steal_lock(lock, task)) { /* We got the lock for task. */ debug_rt_mutex_lock(lock); - rt_mutex_set_owner(lock, task, 0); - + spin_unlock(&lock->wait_lock); rt_mutex_deadlock_account_lock(lock, task); return 1; } ret = task_blocks_on_rt_mutex(lock, waiter, task, detect_deadlock); - if (ret && !waiter->task) { /* * Reset the return value. We might have -- Darren Hart IBM Linux Technology Center Real-Time Linux Team
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