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authorTomoki Sekiyama <tomoki.sekiyama@hds.com>2013-10-15 16:42:19 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-12-08 07:29:27 -0800
commit72b9401c2f5ac465d97969ef7933753642bde8bf (patch)
tree8cc1c1de6433edd93ca7bf744b84c4884e3a16e3 /block
parent6d53d39270ccd29938dcbd611a44870c63032521 (diff)
downloadlinaro-lsk-72b9401c2f5ac465d97969ef7933753642bde8bf.tar.gz
elevator: acquire q->sysfs_lock in elevator_change()
commit 7c8a3679e3d8e9d92d58f282161760a0e247df97 upstream. Add locking of q->sysfs_lock into elevator_change() (an exported function) to ensure it is held to protect q->elevator from elevator_init(), even if elevator_change() is called from non-sysfs paths. sysfs path (elv_iosched_store) uses __elevator_change(), non-locking version, as the lock is already taken by elv_iosched_store(). Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Cc: Josh Boyer <jwboyer@fedoraproject.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
-rw-r--r--block/elevator.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/block/elevator.c b/block/elevator.c
index 02d4390afee..6d765f7e2b2 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -965,7 +965,7 @@ fail_init:
/*
* Switch this queue to the given IO scheduler.
*/
-int elevator_change(struct request_queue *q, const char *name)
+static int __elevator_change(struct request_queue *q, const char *name)
{
char elevator_name[ELV_NAME_MAX];
struct elevator_type *e;
@@ -987,6 +987,18 @@ int elevator_change(struct request_queue *q, const char *name)
return elevator_switch(q, e);
}
+
+int elevator_change(struct request_queue *q, const char *name)
+{
+ int ret;
+
+ /* Protect q->elevator from elevator_init() */
+ mutex_lock(&q->sysfs_lock);
+ ret = __elevator_change(q, name);
+ mutex_unlock(&q->sysfs_lock);
+
+ return ret;
+}
EXPORT_SYMBOL(elevator_change);
ssize_t elv_iosched_store(struct request_queue *q, const char *name,
@@ -997,7 +1009,7 @@ ssize_t elv_iosched_store(struct request_queue *q, const char *name,
if (!q->elevator)
return count;
- ret = elevator_change(q, name);
+ ret = __elevator_change(q, name);
if (!ret)
return count;