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| author | Tomoki Sekiyama <tomoki.sekiyama@hds.com> | 2013-10-15 16:42:19 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-08 07:29:43 -0800 |
| commit | 9e23d8bd64e49062faf4aa4abcedd3943cf1d09d (patch) | |
| tree | 89bc0a5145047109664a1d729326a1e52cfcf085 /block | |
| parent | 3dc062d269601c3f2f9860e9033906d303661622 (diff) | |
| download | lwn-9e23d8bd64e49062faf4aa4abcedd3943cf1d09d.tar.gz lwn-9e23d8bd64e49062faf4aa4abcedd3943cf1d09d.zip | |
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.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/block/elevator.c b/block/elevator.c index f016855a46b0..dcef5d1bf999 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -961,7 +961,7 @@ fail_register: /* * 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; @@ -983,6 +983,18 @@ 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, @@ -993,7 +1005,7 @@ 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; |