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authorLinus Torvalds <torvalds@linux-foundation.org>2011-09-21 13:20:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-09-21 13:20:21 -0700
commitfed678dc8a8b839c8189b5d889a94e865cd327dd (patch)
treed2bf10d2a4e4ca0a27ccd6f7ae40e8e259acfcfc /mm
parent808bf29b9195c52239b9aaeda7c6082a0ddf07c6 (diff)
parent6c4867f6469964e34c5f4ee229a2a7f71a34c7ff (diff)
downloadlinux-linaro-precise-fed678dc8a8b839c8189b5d889a94e865cd327dd.tar.gz
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.c30
1 files changed, 21 insertions, 9 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index d6edf8d14f9..a87da524a4a 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;