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authorMing Lei <ming.lei@redhat.com>2019-07-24 11:48:40 +0800
committerJens Axboe <axboe@kernel.dk>2019-08-04 21:41:29 -0600
commitf9934a80f91dba8c7029ba7601459e41ea7770aa (patch)
tree46a0aff51a0f51bf585ab59302ad06bc6cda9097 /block/blk-mq-tag.c
parentaa306ab703e9452b1e25cc8e8f04b8df523d0bb8 (diff)
blk-mq: introduce blk_mq_tagset_wait_completed_request()
blk-mq may schedule to call queue's complete function on remote CPU via IPI, but doesn't provide any way to synchronize the request's complete fn. The current queue freeze interface can't provide the synchonization because aborted requests stay at blk-mq queues during EH. In some driver's EH(such as NVMe), hardware queue's resource may be freed & re-allocated. If the completed request's complete fn is run finally after the hardware queue's resource is released, kernel crash will be triggered. Prepare for fixing this kind of issue by introducing blk_mq_tagset_wait_completed_request(). Cc: Max Gurtovoy <maxg@mellanox.com> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Keith Busch <keith.busch@intel.com> Cc: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-mq-tag.c')
-rw-r--r--block/blk-mq-tag.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index da19f0bc8876..008388e82b5c 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -10,6 +10,7 @@
#include <linux/module.h>
#include <linux/blk-mq.h>
+#include <linux/delay.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-tag.h"
@@ -354,6 +355,37 @@ void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
}
EXPORT_SYMBOL(blk_mq_tagset_busy_iter);
+static bool blk_mq_tagset_count_completed_rqs(struct request *rq,
+ void *data, bool reserved)
+{
+ unsigned *count = data;
+
+ if (blk_mq_request_completed(rq))
+ (*count)++;
+ return true;
+}
+
+/**
+ * blk_mq_tagset_wait_completed_request - wait until all completed req's
+ * complete funtion is run
+ * @tagset: Tag set to drain completed request
+ *
+ * Note: This function has to be run after all IO queues are shutdown
+ */
+void blk_mq_tagset_wait_completed_request(struct blk_mq_tag_set *tagset)
+{
+ while (true) {
+ unsigned count = 0;
+
+ blk_mq_tagset_busy_iter(tagset,
+ blk_mq_tagset_count_completed_rqs, &count);
+ if (!count)
+ break;
+ msleep(5);
+ }
+}
+EXPORT_SYMBOL(blk_mq_tagset_wait_completed_request);
+
/**
* blk_mq_queue_tag_busy_iter - iterate over all requests with a driver tag
* @q: Request queue to examine.