From 25705e3a3e9f91280b51124a28e74418aff00c7d 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 commit 62d3c5439c534b0e6c653fc63e6d8c67be3a57b1 upstream. 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 Acked-by: Tejun Heo Acked-by: Rafael J. Wysocki Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/genhd.c | 10 +++++----- include/linux/workqueue.h | 4 ++++ kernel/workqueue.c | 7 ++++++- 3 files changed, 15 insertions(+), 6 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 091429d..f6ecddb 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1487,9 +1487,9 @@ static void __disk_unblock_events(struct gendisk *disk, bool check_now) intv = disk_events_poll_jiffies(disk); set_timer_slack(&ev->dwork.timer, intv / 4); if (check_now) - queue_delayed_work(system_nrt_wq, &ev->dwork, 0); + queue_delayed_work(system_nrt_freezable_wq, &ev->dwork, 0); else if (intv) - queue_delayed_work(system_nrt_wq, &ev->dwork, intv); + queue_delayed_work(system_nrt_freezable_wq, &ev->dwork, intv); out_unlock: spin_unlock_irqrestore(&ev->lock, flags); } @@ -1530,7 +1530,7 @@ void disk_check_events(struct gendisk *disk) spin_lock_irqsave(&ev->lock, flags); if (!ev->block) { cancel_delayed_work(&ev->dwork); - queue_delayed_work(system_nrt_wq, &ev->dwork, 0); + queue_delayed_work(system_nrt_freezable_wq, &ev->dwork, 0); } spin_unlock_irqrestore(&ev->lock, flags); } @@ -1568,7 +1568,7 @@ unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask) /* uncondtionally schedule event check and wait for it to finish */ disk_block_events(disk); - queue_delayed_work(system_nrt_wq, &ev->dwork, 0); + queue_delayed_work(system_nrt_freezable_wq, &ev->dwork, 0); flush_delayed_work(&ev->dwork); __disk_unblock_events(disk, false); @@ -1605,7 +1605,7 @@ static void disk_events_workfn(struct work_struct *work) intv = disk_events_poll_jiffies(disk); if (!ev->block && intv) - queue_delayed_work(system_nrt_wq, &ev->dwork, intv); + queue_delayed_work(system_nrt_freezable_wq, &ev->dwork, intv); spin_unlock_irq(&ev->lock); diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index f584aba..6c56a14 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -289,12 +289,16 @@ enum { * * system_freezable_wq is equivalent to system_wq except that it's * freezable. + * + * system_nrt_freezable_wq is equivalent to system_nrt_wq except that + * it's freezable. */ extern struct workqueue_struct *system_wq; extern struct workqueue_struct *system_long_wq; extern struct workqueue_struct *system_nrt_wq; extern struct workqueue_struct *system_unbound_wq; extern struct workqueue_struct *system_freezable_wq; +extern struct workqueue_struct *system_nrt_freezable_wq; extern struct workqueue_struct * __alloc_workqueue_key(const char *name, unsigned int flags, int max_active, diff --git a/kernel/workqueue.c b/kernel/workqueue.c index aec02b6..1456dab 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -252,11 +252,13 @@ 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 @@ -3796,8 +3798,11 @@ 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 v1.1