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| author | Nick Piggin <npiggin@suse.de> | 2008-04-29 14:48:33 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-04-29 14:48:33 +0200 |
| commit | 75ad23bc0fcb4f992a5d06982bf0857ab1738e9e (patch) | |
| tree | 8668ef63b1f420252ae41aed9e13737d49fd8054 /block/elevator.c | |
| parent | 68154e90c9d1492d570671ae181d9a8f8530da55 (diff) | |
| download | lwn-75ad23bc0fcb4f992a5d06982bf0857ab1738e9e.tar.gz lwn-75ad23bc0fcb4f992a5d06982bf0857ab1738e9e.zip | |
block: make queue flags non-atomic
We can save some atomic ops in the IO path, if we clearly define
the rules of how to modify the queue flags.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/elevator.c')
| -rw-r--r-- | block/elevator.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/block/elevator.c b/block/elevator.c index 88318c383608..e8a90fe23424 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -1070,7 +1070,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) */ spin_lock_irq(q->queue_lock); - set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); elv_drain_elevator(q); @@ -1104,7 +1104,10 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) * finally exit old elevator and turn off BYPASS. */ elevator_exit(old_elevator); - clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + spin_lock_irq(q->queue_lock); + queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); + spin_unlock_irq(q->queue_lock); + return 1; fail_register: @@ -1115,7 +1118,11 @@ fail_register: elevator_exit(e); q->elevator = old_elevator; elv_register_queue(q); - clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + + spin_lock_irq(q->queue_lock); + queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); + spin_unlock_irq(q->queue_lock); + return 0; } |