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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: Tomoki Sekiyama <tomoki.sekiyama@hds.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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@ -965,7 +965,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
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/*
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* Switch this queue to the given IO scheduler.
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*/
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int elevator_change(struct request_queue *q, const char *name)
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static int __elevator_change(struct request_queue *q, const char *name)
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{
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char elevator_name[ELV_NAME_MAX];
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struct elevator_type *e;
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@ -987,6 +987,18 @@ int elevator_change(struct request_queue *q, const char *name)
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return elevator_switch(q, e);
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}
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int elevator_change(struct request_queue *q, const char *name)
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{
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int ret;
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/* Protect q->elevator from elevator_init() */
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mutex_lock(&q->sysfs_lock);
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ret = __elevator_change(q, name);
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mutex_unlock(&q->sysfs_lock);
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return ret;
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}
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EXPORT_SYMBOL(elevator_change);
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ssize_t elv_iosched_store(struct request_queue *q, const char *name,
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@ -997,7 +1009,7 @@ ssize_t elv_iosched_store(struct request_queue *q, const char *name,
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if (!q->elevator)
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return count;
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ret = elevator_change(q, name);
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ret = __elevator_change(q, name);
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if (!ret)
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return count;
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