From 62d3c5439c534b0e6c653fc63e6d8c67be3a57b1 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Fri, 2 Mar 2012 10:51:00 +0100 Subject: Block: use a freezable workqueue for disk-event polling This patch (as1519) fixes a bug in the block layer's disk-events polling. The polling is done by a work routine queued on the system_nrt_wq workqueue. Since that workqueue isn't freezable, the polling continues even in the middle of a system sleep transition. Obviously, polling a suspended drive for media changes and such isn't a good thing to do; in the case of USB mass-storage devices it can lead to real problems requiring device resets and even re-enumeration. The patch fixes things by creating a new system-wide, non-reentrant, freezable workqueue and using it for disk-events polling. Signed-off-by: Alan Stern CC: Acked-by: Tejun Heo Acked-by: Rafael J. Wysocki Signed-off-by: Jens Axboe --- kernel/workqueue.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index bec7b5b53e03..f2c5638bb5ab 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -253,11 +253,13 @@ struct workqueue_struct *system_long_wq __read_mostly; struct workqueue_struct *system_nrt_wq __read_mostly; struct workqueue_struct *system_unbound_wq __read_mostly; struct workqueue_struct *system_freezable_wq __read_mostly; +struct workqueue_struct *system_nrt_freezable_wq __read_mostly; EXPORT_SYMBOL_GPL(system_wq); EXPORT_SYMBOL_GPL(system_long_wq); EXPORT_SYMBOL_GPL(system_nrt_wq); EXPORT_SYMBOL_GPL(system_unbound_wq); EXPORT_SYMBOL_GPL(system_freezable_wq); +EXPORT_SYMBOL_GPL(system_nrt_freezable_wq); #define CREATE_TRACE_POINTS #include @@ -3833,8 +3835,11 @@ static int __init init_workqueues(void) WQ_UNBOUND_MAX_ACTIVE); system_freezable_wq = alloc_workqueue("events_freezable", WQ_FREEZABLE, 0); + system_nrt_freezable_wq = alloc_workqueue("events_nrt_freezable", + WQ_NON_REENTRANT | WQ_FREEZABLE, 0); BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq || - !system_unbound_wq || !system_freezable_wq); + !system_unbound_wq || !system_freezable_wq || + !system_nrt_freezable_wq); return 0; } early_initcall(init_workqueues); -- cgit v1.2.3