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-rw-r--r--block/blk-core.c18
-rw-r--r--include/linux/blkdev.h13
-rw-r--r--include/trace/events/block.h13
-rw-r--r--kernel/sched.c2
-rw-r--r--kernel/trace/blktrace.c18
5 files changed, 45 insertions, 19 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 3c81210..78b7b0c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2662,17 +2662,23 @@ static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
return !(rqa->q <= rqb->q);
}
+/*
+ * If 'from_schedule' is true, then postpone the dispatch of requests
+ * until a safe kblockd context. We due this to avoid accidental big
+ * additional stack usage in driver dispatch, in places where the originally
+ * plugger did not intend it.
+ */
static void queue_unplugged(struct request_queue *q, unsigned int depth,
- bool force_kblockd)
+ bool from_schedule)
{
- trace_block_unplug_io(q, depth);
- __blk_run_queue(q, force_kblockd);
+ trace_block_unplug(q, depth, !from_schedule);
+ __blk_run_queue(q, from_schedule);
if (q->unplugged_fn)
q->unplugged_fn(q);
}
-void blk_flush_plug_list(struct blk_plug *plug, bool force_kblockd)
+void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
struct request_queue *q;
unsigned long flags;
@@ -2707,7 +2713,7 @@ void blk_flush_plug_list(struct blk_plug *plug, bool force_kblockd)
BUG_ON(!rq->q);
if (rq->q != q) {
if (q) {
- queue_unplugged(q, depth, force_kblockd);
+ queue_unplugged(q, depth, from_schedule);
spin_unlock(q->queue_lock);
}
q = rq->q;
@@ -2728,7 +2734,7 @@ void blk_flush_plug_list(struct blk_plug *plug, bool force_kblockd)
}
if (q) {
- queue_unplugged(q, depth, force_kblockd);
+ queue_unplugged(q, depth, from_schedule);
spin_unlock(q->queue_lock);
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1c76506..ec0357d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -872,6 +872,14 @@ static inline void blk_flush_plug(struct task_struct *tsk)
struct blk_plug *plug = tsk->plug;
if (plug)
+ blk_flush_plug_list(plug, false);
+}
+
+static inline void blk_schedule_flush_plug(struct task_struct *tsk)
+{
+ struct blk_plug *plug = tsk->plug;
+
+ if (plug)
blk_flush_plug_list(plug, true);
}
@@ -1317,6 +1325,11 @@ static inline void blk_flush_plug(struct task_struct *task)
{
}
+static inline void blk_schedule_flush_plug(struct task_struct *task)
+{
+}
+
+
static inline bool blk_needs_flush_plug(struct task_struct *tsk)
{
return false;
diff --git a/include/trace/events/block.h b/include/trace/events/block.h
index 006e60b..bf36654 100644
--- a/include/trace/events/block.h
+++ b/include/trace/events/block.h
@@ -401,9 +401,9 @@ TRACE_EVENT(block_plug,
DECLARE_EVENT_CLASS(block_unplug,
- TP_PROTO(struct request_queue *q, unsigned int depth),
+ TP_PROTO(struct request_queue *q, unsigned int depth, bool explicit),
- TP_ARGS(q, depth),
+ TP_ARGS(q, depth, explicit),
TP_STRUCT__entry(
__field( int, nr_rq )
@@ -419,18 +419,19 @@ DECLARE_EVENT_CLASS(block_unplug,
);
/**
- * block_unplug_io - release of operations requests in request queue
+ * block_unplug - release of operations requests in request queue
* @q: request queue to unplug
* @depth: number of requests just added to the queue
+ * @explicit: whether this was an explicit unplug, or one from schedule()
*
* Unplug request queue @q because device driver is scheduled to work
* on elements in the request queue.
*/
-DEFINE_EVENT(block_unplug, block_unplug_io,
+DEFINE_EVENT(block_unplug, block_unplug,
- TP_PROTO(struct request_queue *q, unsigned int depth),
+ TP_PROTO(struct request_queue *q, unsigned int depth, bool explicit),
- TP_ARGS(q, depth)
+ TP_ARGS(q, depth, explicit)
);
/**
diff --git a/kernel/sched.c b/kernel/sched.c
index a187c3f..312f8b9 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4118,7 +4118,7 @@ need_resched:
*/
if (blk_needs_flush_plug(prev)) {
raw_spin_unlock(&rq->lock);
- blk_flush_plug(prev);
+ blk_schedule_flush_plug(prev);
raw_spin_lock(&rq->lock);
}
}
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 3e3970d..6957aa2 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -850,16 +850,21 @@ static void blk_add_trace_plug(void *ignore, struct request_queue *q)
__blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
}
-static void blk_add_trace_unplug_io(void *ignore, struct request_queue *q,
- unsigned int depth)
+static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
+ unsigned int depth, bool explicit)
{
struct blk_trace *bt = q->blk_trace;
if (bt) {
__be64 rpdu = cpu_to_be64(depth);
+ u32 what;
- __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
- sizeof(rpdu), &rpdu);
+ if (explicit)
+ what = BLK_TA_UNPLUG_IO;
+ else
+ what = BLK_TA_UNPLUG_TIMER;
+
+ __blk_add_trace(bt, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
}
}
@@ -1002,7 +1007,7 @@ static void blk_register_tracepoints(void)
WARN_ON(ret);
ret = register_trace_block_plug(blk_add_trace_plug, NULL);
WARN_ON(ret);
- ret = register_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
+ ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
WARN_ON(ret);
ret = register_trace_block_split(blk_add_trace_split, NULL);
WARN_ON(ret);
@@ -1017,7 +1022,7 @@ static void blk_unregister_tracepoints(void)
unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
unregister_trace_block_split(blk_add_trace_split, NULL);
- unregister_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
+ unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
unregister_trace_block_plug(blk_add_trace_plug, NULL);
unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
@@ -1332,6 +1337,7 @@ static const struct {
[__BLK_TA_COMPLETE] = {{ "C", "complete" }, blk_log_with_error },
[__BLK_TA_PLUG] = {{ "P", "plug" }, blk_log_plug },
[__BLK_TA_UNPLUG_IO] = {{ "U", "unplug_io" }, blk_log_unplug },
+ [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
[__BLK_TA_INSERT] = {{ "I", "insert" }, blk_log_generic },
[__BLK_TA_SPLIT] = {{ "X", "split" }, blk_log_split },
[__BLK_TA_BOUNCE] = {{ "B", "bounce" }, blk_log_generic },
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