Commit 62d3c543 authored by Alan Stern's avatar Alan Stern Committed by Jens Axboe
Browse files

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: default avatarAlan Stern <stern@rowland.harvard.edu>
CC: <stable@kernel.org>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent cecd353a

block/genhd.c

+5 −5
Original line number Diff line number Diff line
@@ -1478,9 +1478,9 @@ 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);

}
@@ -1524,7 +1524,7 @@ void disk_flush_events(struct gendisk *disk, unsigned int mask) 
	ev->clearing |= mask;

	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_irq(&ev->lock);

}
@@ -1561,7 +1561,7 @@ 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);
@@ -1598,7 +1598,7 @@ 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);

include/linux/workqueue.h

+4 −0
Original line number Diff line number Diff line
@@ -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 *fmt, unsigned int flags, int max_active,

kernel/workqueue.c

+6 −1
Original line number Diff line number Diff line
@@ -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 <trace/events/workqueue.h>
@@ -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);

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