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authorAlan Stern <stern@rowland.harvard.edu>2012-03-02 10:51:00 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-03-19 09:02:34 -0700
commit2053689f68e19b8c1bb38aa68049c57576eed6e0 (patch)
treee46163b3f66816e302822f2ce6b62466b6f50b63
parenteee92c36399fe1c0d19de4982e9cfdf526b37922 (diff)
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 <stern@rowland.harvard.edu> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--block/genhd.c10
-rw-r--r--include/linux/workqueue.h4
-rw-r--r--kernel/workqueue.c7
3 files changed, 15 insertions, 6 deletions
diff --git a/block/genhd.c b/block/genhd.c
index 9db720dca99c..997afd642bd6 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1479,9 +1479,9 @@ 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);
}
@@ -1525,7 +1525,7 @@ 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);
}
@@ -1562,7 +1562,7 @@ 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);
@@ -1599,7 +1599,7 @@ 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 0d556deb497b..e228ca9e1b5a 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 42fa9ad0a810..bb425b16372e 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 <trace/events/workqueue.h>
@@ -3821,8 +3823,11 @@ 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);