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Commit 7c8a3679 authored by Tomoki Sekiyama's avatar Tomoki Sekiyama Committed by Jens Axboe
Browse files

elevator: acquire q->sysfs_lock in elevator_change() 



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: default avatarTomoki Sekiyama <tomoki.sekiyama@hds.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent eb1c160b

block/elevator.c

+14 −2
Original line number Diff line number Diff line
@@ -965,7 +965,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) 
/*

 * 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;