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@xxxxxx>
---
block/blk-core.c | 8 ++++++++
block/blk-mq.c | 11 ++++++++---
block/blk-timeout.c | 8 ++++++--
block/blk.h | 2 +-
include/linux/blkdev.h | 1 +
5 files changed, 24 insertions(+), 6 deletions(-)
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 @@ static void blk_queue_usage_counter_release(struct percpu_ref *ref)
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 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
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;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 93a4e19..9cb2894 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -615,15 +615,19 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
}
}
-static void blk_mq_rq_timer(unsigned long priv)
+static void blk_mq_timeout_work(struct work_struct *work)
{
- struct request_queue *q = (struct request_queue *)priv;
+ struct request_queue *q =
+ container_of(work, struct request_queue, timeout_work);
struct blk_mq_timeout_data data = {
.next = 0,
.next_set = 0,
};
int i;
+ if (blk_queue_enter(q, true))
+ return;
+
blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
if (data.next_set) {
@@ -638,6 +642,7 @@ static void blk_mq_rq_timer(unsigned long priv)
blk_mq_tag_idle(hctx);
}
}
+ blk_queue_exit(q);
}
/*
@@ -2015,7 +2020,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
hctxs[i]->queue_num = i;
}
- setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
+ INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
q->nr_queues = nr_cpu_ids;
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index 3610af5..dd4fdfb 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -127,13 +127,16 @@ static void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout
}
}
-void blk_rq_timed_out_timer(unsigned long data)
+void blk_timeout_work(struct work_struct *work)
{
- struct request_queue *q = (struct request_queue *) data;
+ struct request_queue *q =
+ container_of(work, struct request_queue, timeout_work);
unsigned long flags, next = 0;
struct request *rq, *tmp;
int next_set = 0;
+ if (blk_queue_enter(q, true))
+ return;
spin_lock_irqsave(q->queue_lock, flags);
list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
@@ -143,6 +146,7 @@ void blk_rq_timed_out_timer(unsigned long data)
mod_timer(&q->timeout, round_jiffies_up(next));
spin_unlock_irqrestore(q->queue_lock, flags);
+ blk_queue_exit(q);
}
/**
diff --git a/block/blk.h b/block/blk.h
index c43926d..70e4aee 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -93,7 +93,7 @@ static inline void blk_flush_integrity(void)
}
#endif
-void blk_rq_timed_out_timer(unsigned long data);
+void blk_timeout_work(struct work_struct *work);
unsigned long blk_rq_timeout(unsigned long timeout);
void blk_add_timer(struct request *req);
void blk_delete_timer(struct request *);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e711f29..221dc3b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -407,6 +407,7 @@ struct request_queue {
unsigned int rq_timeout;
struct timer_list timeout;
+ struct work_struct timeout_work;
struct list_head timeout_list;
struct list_head icq_list;
--
1.9.1
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