Re: [PATCH] Fix deadlock in __create_workqueue

[Andrew Morton <akpm@osdl.org>]

Srivatsa Vaddagiri <vatsa@in.ibm.com> wrote:
>
> Noticed a possible deadlock in __create_workqueue when CONFIG_HOTPLUG_CPU is
>  set.  This can happen when create_workqueue_thread fails to create a worker
>  thread. In that case, we call destroy_workqueue with cpu hotplug lock held.
>  destroy_workqueue however also attempts to take the same lock.

Can we not simply do:


diff -puN kernel/workqueue.c~a kernel/workqueue.c
--- 25/kernel/workqueue.c~a	2004-04-30 19:26:32.003303600 -0700
+++ 25-akpm/kernel/workqueue.c	2004-04-30 19:26:44.492404968 -0700
@@ -334,6 +334,7 @@ struct workqueue_struct *__create_workqu
 				destroy = 1;
 		}
 	}
+	unlock_cpu_hotplug();
 
 	/*
 	 * Was there any error during startup? If yes then clean up:
@@ -342,7 +343,6 @@ struct workqueue_struct *__create_workqu
 		destroy_workqueue(wq);
 		wq = NULL;
 	}
-	unlock_cpu_hotplug();
 	return wq;
 }
 

_