summaryrefslogtreecommitdiff
path: root/.mailmap
diff options
context:
space:
mode:
authorSteven Rostedt <rostedt@goodmis.org>2012-01-31 16:22:16 -0500
committerClark Williams <williams@redhat.com>2012-01-31 15:32:24 -0600
commitd28048db190097536aef2be5ee9a736bd7bb92eb (patch)
tree4f430e29211f01154d0a2da4a103cd5634f1a39c /.mailmap
parent974f4b86951972b133b4ec5b36956b979dea08d0 (diff)
Bug with futex requeue piv3.2.2-rt10
I found the problem: The bug comes from a timed out condition. TASK 1 TASK 2 ------ ------ futex_wait_requeue_pi() futex_wait_queue_me() <timed out> double_lock_hb(); raw_spin_lock(pi_lock); if (current->pi_blocked_on) { } else { current->pi_blocked_on = PI_WAKE_INPROGRESS; run_spin_unlock(pi_lock); spin_lock(hb->lock); <-- blocked! plist_for_each_entry_safe(this) { rt_mutex_start_proxy_lock(); task_blocks_on_rt_mutex(); BUG_ON(task->pi_blocked_on)!!!! The BUG_ON() actually has a check for PI_WAKE_INPROGRESS, but the problem is that, after TASK 1 sets PI_WAKE_INPROGRESS, it then tries to grab the hb->lock, which it fails to do so. As the hb->lock is a mutex, it will block and set the "pi_blocked_on" to the hb->lock. When TASK 2 goes to requeue it, the check for PI_WAKE_INPROGESS fails because the task1's pi_blocked_on is no longer set to that, but instead, set to the hb->lock. We need a way in rt_mutex_start_proxy_lock() to prevent this. I just added the below patch, which makes the bug go away. It's a little ugly (but no more ugly than the pi futex_requeue already is ;-) -- Steve Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to '.mailmap')
0 files changed, 0 insertions, 0 deletions