Messages in this thread | | | Date | Sun, 22 Sep 2013 13:04:17 -0400 | From | Tejun Heo <> | Subject | Re: [PATCH v2 1/2] elevator: Fix a race in elevator switching and md device initialization |
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On Fri, Aug 30, 2013 at 06:47:07PM -0400, Tomoki Sekiyama wrote: > @@ -739,9 +739,17 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, > > q->sg_reserved_size = INT_MAX; > > + /* Protect q->elevator from elevator_change */ > + mutex_lock(&q->sysfs_lock); > + > /* init elevator */ > - if (elevator_init(q, NULL)) > + if (elevator_init(q, NULL)) { > + mutex_unlock(&q->sysfs_lock); > return NULL; > + } > + > + mutex_unlock(&q->sysfs_lock); > + > return q; > } > EXPORT_SYMBOL(blk_init_allocated_queue); > diff --git a/block/elevator.c b/block/elevator.c > index 668394d..02d4390 100644 > --- a/block/elevator.c > +++ b/block/elevator.c > @@ -186,6 +186,12 @@ int elevator_init(struct request_queue *q, char *name) > struct elevator_type *e = NULL; > int err; > > + /* > + * q->sysfs_lock must be held to provide mutual exclusion between > + * elevator_switch() and here. > + */ > + lockdep_assert_held(&q->sysfs_lock); > + > if (unlikely(q->elevator)) > return 0;
Hmm... why aren't we just changing elevator_init() to grab sysfs_lock where necessary? It'd be more consistent with elevator_exit() that way.
Thanks.
-- tejun
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