block: defer timeouts to a workqueue
Timer context is not very useful for drivers to perform any meaningful abort
action from. So instead of calling the driver from this useless context
defer it to a workqueue as soon as possible.
Note that while a delayed_work item would seem the right thing here I didn't
dare to use it due to the magic in blk_add_timer that pokes deep into timer
internals. But maybe this encourages Tejun to add a sensible API for that to
the workqueue API and we'll all be fine in the end :)
Contains a major update from Keith Bush:
"This patch removes synchronizing the timeout work so that the timer can
start a freeze on its own queue. The timer enters the queue, so timer
context can only start a freeze, but not wait for frozen."
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index 5ec9960..7e01002 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -664,6 +664,13 @@
wake_up_all(&q->mq_freeze_wq);
}
+static void blk_rq_timed_out_timer(unsigned long data)
+{
+ struct request_queue *q = (struct request_queue *)data;
+
+ kblockd_schedule_work(&q->timeout_work);
+}
+
struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
{
struct request_queue *q;
@@ -825,6 +832,7 @@
if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
goto fail;
+ INIT_WORK(&q->timeout_work, blk_timeout_work);
q->request_fn = rfn;
q->prep_rq_fn = NULL;
q->unprep_rq_fn = NULL;