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author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-09-21 20:20:21 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-09-21 20:20:21 (GMT) |
commit | fed678dc8a8b839c8189b5d889a94e865cd327dd (patch) | |
tree | d2bf10d2a4e4ca0a27ccd6f7ae40e8e259acfcfc /mm | |
parent | 808bf29b9195c52239b9aaeda7c6082a0ddf07c6 (diff) | |
parent | 6c4867f6469964e34c5f4ee229a2a7f71a34c7ff (diff) | |
download | linux-fed678dc8a8b839c8189b5d889a94e865cd327dd.tar.xz |
Merge branch 'for-linus' of git://git.kernel.dk/linux-block
* 'for-linus' of git://git.kernel.dk/linux-block:
floppy: use del_timer_sync() in init cleanup
blk-cgroup: be able to remove the record of unplugged device
block: Don't check QUEUE_FLAG_SAME_COMP in __blk_complete_request
mm: Add comment explaining task state setting in bdi_forker_thread()
mm: Cleanup clearing of BDI_pending bit in bdi_forker_thread()
block: simplify force plug flush code a little bit
block: change force plug flush call order
block: Fix queue_flag update when rq_affinity goes from 2 to 1
block: separate priority boosting from REQ_META
block: remove READ_META and WRITE_META
xen-blkback: fixed indentation and comments
xen-blkback: Don't disconnect backend until state switched to XenbusStateClosed.
Diffstat (limited to 'mm')
-rw-r--r-- | mm/backing-dev.c | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c index d6edf8d..a87da52 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -359,6 +359,17 @@ static unsigned long bdi_longest_inactive(void) return max(5UL * 60 * HZ, interval); } +/* + * Clear pending bit and wakeup anybody waiting for flusher thread creation or + * shutdown + */ +static void bdi_clear_pending(struct backing_dev_info *bdi) +{ + clear_bit(BDI_pending, &bdi->state); + smp_mb__after_clear_bit(); + wake_up_bit(&bdi->state, BDI_pending); +} + static int bdi_forker_thread(void *ptr) { struct bdi_writeback *me = ptr; @@ -390,6 +401,13 @@ static int bdi_forker_thread(void *ptr) } spin_lock_bh(&bdi_lock); + /* + * In the following loop we are going to check whether we have + * some work to do without any synchronization with tasks + * waking us up to do work for them. So we have to set task + * state already here so that we don't miss wakeups coming + * after we verify some condition. + */ set_current_state(TASK_INTERRUPTIBLE); list_for_each_entry(bdi, &bdi_list, bdi_list) { @@ -469,11 +487,13 @@ static int bdi_forker_thread(void *ptr) spin_unlock_bh(&bdi->wb_lock); wake_up_process(task); } + bdi_clear_pending(bdi); break; case KILL_THREAD: __set_current_state(TASK_RUNNING); kthread_stop(task); + bdi_clear_pending(bdi); break; case NO_ACTION: @@ -489,16 +509,8 @@ static int bdi_forker_thread(void *ptr) else schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); try_to_freeze(); - /* Back to the main loop */ - continue; + break; } - - /* - * Clear pending bit and wakeup anybody waiting to tear us down. - */ - clear_bit(BDI_pending, &bdi->state); - smp_mb__after_clear_bit(); - wake_up_bit(&bdi->state, BDI_pending); } return 0; |