[Openais] [PATCH 6/7] aisexec crash on exit

[angus salkeld]

Committed as revision 1658.

-Angus

On Tue, 2008-08-19 at 16:23 -0700, Steven Dake wrote:
> looks good for commit.
> 
> thanks for the work!
> 
> -steve
> On Wed, 2008-08-20 at 06:55 +1200, angus salkeld wrote:
> > Cause:
> > As part of its exit procedure, ais cancels its worker thread then manually
> > processes any outstanding items that were still in the worker thread's queue.
> > The worker thread has a low priority so normally it does not execute any
> > further before ais finishes exiting, but if the main thread's exiting is
> > delayed for any reason, there is a chance the worker thread could execute and
> > try to process items which have already been processed and freed by the main
> > thread - often leading to the worker thread seeing NULL data and ultimately
> > causing a segmentation fault.
> > 
> > Fix:
> > Modified worker_thread_group_exit() so it does a pthread_join() after the
> > pthread_cancel() call, so that the worker thread always shuts down cleanly
> > before the main thread does its cleanup.
> > 
> > Author: Author: Mark McKinstry <mark.mckinstry at alliedtelesis.co.nz>
> > ---
> >  exec/wthread.c |    5 +++++
> >  1 files changed, 5 insertions(+), 0 deletions(-)
> > 
> > diff --git a/exec/wthread.c b/exec/wthread.c
> > index 6a434fd..e97f917 100644
> > --- a/exec/wthread.c
> > +++ b/exec/wthread.c
> > @@ -183,6 +183,11 @@ void worker_thread_group_exit (
> >  
> >  	for (i = 0; i < worker_thread_group->threadcount; i++) {
> >  		pthread_cancel (worker_thread_group->threads[i].thread_id);
> > +
> > +		/* Wait for worker thread to exit gracefully before destroying
> > +		 * mutexes and processing items in the queue etc.
> > +		 */
> > +		pthread_join (worker_thread_group->threads[i].thread_id, NULL);
> >  		pthread_mutex_destroy (&worker_thread_group->threads[i].new_work_mutex);
> >  		pthread_cond_destroy (&worker_thread_group->threads[i].new_work_cond);
> >  		pthread_mutex_destroy (&worker_thread_group->threads[i].done_work_mutex);
> 
-- 
*********************************************************************
Angus Salkeld
Specialist Software Engineer

27 Nazareth Ave
PO Box 8011
Christchurch 8035
Allied Telesis Labs Ltd.
New Zealand
Email:  angus.salkeld at alliedtelesyn.co.nz    
        http://www.alliedtelesyn.co.nz  
DDI: +64 3 339 9667  Fax:+64 3 339 3001         
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