[RFC][PATCH 09/16] writeback: do not lose wake-ups in bdi threads
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From: Artem Bityutskiy on 16 Jul 2010 09:00 From: Artem Bityutskiy <Artem.Bityutskiy(a)nokia.com> The bdi threads ('bdi_writeback_thread()') can lose wake-ups if, for example, 'bdi_queue_work()' is executed while after the bdi thread finished 'wb_do_writeback()' but before it has called 'schedule_timeout_interruptible()'. To fix this issue, we have to check whether we have works to process after we change the task state to 'TASK_INTERRUPTIBLE'. Also, 'bdi_writeback_thread()' inconsistently handles the cases when 'dirty_writeback_interval' is zero and non-zero. But there is no fundamental difference between these cases, so they have to be handled the same way, which this patch also does. This patch also removes strange 'list_empty_careful()' call. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy(a)nokia.com> --- fs/fs-writeback.c | 17 +++++++++-------- 1 files changed, 9 insertions(+), 8 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 3fc5194..f045450 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -848,17 +848,18 @@ int bdi_writeback_thread(void *data) break; } - if (dirty_writeback_interval) { - wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); - schedule_timeout_interruptible(wait_jiffies); - } else { - set_current_state(TASK_INTERRUPTIBLE); - if (list_empty_careful(&wb->bdi->work_list) && - !kthread_should_stop()) - schedule(); + set_current_state(TASK_INTERRUPTIBLE); + if (!list_empty(&bdi->work_list)) { __set_current_state(TASK_RUNNING); + continue; } + if (dirty_writeback_interval) { + wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); + schedule_timeout(wait_jiffies); + } else + schedule(); + try_to_freeze(); } -- 1.7.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |