Re: [RFC][PATCH] Fix hang in posix_locks_deadlock()

2007-11-02 Thread George G. Davis
On Fri, Oct 26, 2007 at 01:07:50PM -0400, J. Bruce Fields wrote: > > It may take multiple steps to identify a deadlock. With the above > you'll miss deadlocks like > > process 1 is requesting a lock held by process 2 > process 2 is blocking on a lock held by process 3 > process

Re: [RFC][PATCH] Fix hang in posix_locks_deadlock()

2007-10-28 Thread J. Bruce Fields
On Fri, Oct 26, 2007 at 06:47:08PM -0400, J. Bruce Fields wrote: > Hm. After another look: assume we have four tasks, t1, t2, t3, and t4. > Assume t1 and t2 share the same current->files (so they're the same > "owner" for the purpose of posix_same_owner()). Assume: > > t1 is waiting on a c

Re: [RFC][PATCH] Fix hang in posix_locks_deadlock()

2007-10-26 Thread J. Bruce Fields
On Fri, Oct 26, 2007 at 01:07:50PM -0400, bfields wrote: > On Thu, Oct 18, 2007 at 02:57:59PM -0400, George G. Davis wrote: > > On Wed, Oct 17, 2007 at 02:51:57PM -0400, George G. Davis wrote: > > > --- > > > Not sure if this is the correct fix but it does resolve the hangs we're > > > observing in

Re: [RFC][PATCH] Fix hang in posix_locks_deadlock()

2007-10-26 Thread J. Bruce Fields
On Thu, Oct 18, 2007 at 02:57:59PM -0400, George G. Davis wrote: > On Wed, Oct 17, 2007 at 02:51:57PM -0400, George G. Davis wrote: > > --- > > Not sure if this is the correct fix but it does resolve the hangs we're > > observing in posix_locks_deadlock(). > > Please disregard the previous patch,

Re: [RFC][PATCH] Fix hang in posix_locks_deadlock()

2007-10-18 Thread George G. Davis
On Wed, Oct 17, 2007 at 02:51:57PM -0400, George G. Davis wrote: > --- > Not sure if this is the correct fix but it does resolve the hangs we're > observing in posix_locks_deadlock(). Please disregard the previous patch, it's not quite right - causes occasional segfaults and clearly did not retain

Re: [RFC][PATCH] Fix hang in posix_locks_deadlock()

2007-10-17 Thread George G. Davis
On Wed, Oct 17, 2007 at 02:51:57PM -0400, George G. Davis wrote: > Not sure if this is the correct fix but it does resolve the hangs we're > observing in posix_locks_deadlock(). Comments greatly appreciated... Attached is a test case which exhibits the hang on an F7 host with all updates applied.

[RFC][PATCH] Fix hang in posix_locks_deadlock()

2007-10-17 Thread George G. Davis
From: Armin Kuster <[EMAIL PROTECTED]> We have observed hangs in posix_locks_deadlock() when multiple threads use fcntl(2) F_SETLKW to synchronize file accesses. The problem appears to be due to an error in the implementation of posix_locks_deadlock() in which "goto next_task" is used to break ou