From: Tejun Heo <tj@kernel.org>
To: jack@suse.cz, axboe@kernel.dk, clm@fb.com, jbacik@fb.com
Cc: kernel-team@fb.com, linux-kernel@vger.kernel.org,
linux-btrfs@vger.kernel.org, peterz@infradead.org,
jianchao.w.wang@oracle.com, Bart.VanAssche@wdc.com,
linux-block@vger.kernel.org, Tejun Heo <tj@kernel.org>,
Asai Thambi SP <asamymuthupa@micron.com>,
Stefan Haberland <sth@linux.vnet.ibm.com>,
Jan Hoeppner <hoeppner@linux.vnet.ibm.com>
Subject: [PATCH 5/8] blk-mq: make blk_abort_request() trigger timeout path
Date: Tue, 9 Jan 2018 08:29:50 -0800 [thread overview]
Message-ID: <20180109162953.1211451-6-tj@kernel.org> (raw)
In-Reply-To: <20180109162953.1211451-1-tj@kernel.org>
With issue/complete and timeout paths now using the generation number
and state based synchronization, blk_abort_request() is the only one
which depends on REQ_ATOM_COMPLETE for arbitrating completion.
There's no reason for blk_abort_request() to be a completely separate
path. This patch makes blk_abort_request() piggyback on the timeout
path instead of trying to terminate the request directly.
This removes the last dependency on REQ_ATOM_COMPLETE in blk-mq.
Note that this makes blk_abort_request() asynchronous - it initiates
abortion but the actual termination will happen after a short while,
even when the caller owns the request. AFAICS, SCSI and ATA should be
fine with that and I think mtip32xx and dasd should be safe but not
completely sure. It'd be great if people who know the drivers take a
look.
v2: - Add comment explaining the lack of synchronization around
->deadline update as requested by Bart.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Asai Thambi SP <asamymuthupa@micron.com>
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Jan Hoeppner <hoeppner@linux.vnet.ibm.com>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
---
block/blk-mq.c | 2 +-
block/blk-mq.h | 2 --
block/blk-timeout.c | 13 +++++++++----
3 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 51e9704..b419746 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -820,7 +820,7 @@ struct blk_mq_timeout_data {
unsigned int nr_expired;
};
-void blk_mq_rq_timed_out(struct request *req, bool reserved)
+static void blk_mq_rq_timed_out(struct request *req, bool reserved)
{
const struct blk_mq_ops *ops = req->q->mq_ops;
enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
diff --git a/block/blk-mq.h b/block/blk-mq.h
index cf01f6f..6b2d616 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -94,8 +94,6 @@ extern int blk_mq_sysfs_register(struct request_queue *q);
extern void blk_mq_sysfs_unregister(struct request_queue *q);
extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);
-extern void blk_mq_rq_timed_out(struct request *req, bool reserved);
-
void blk_mq_release(struct request_queue *q);
/**
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index 6427be7..4f04cd1 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -156,12 +156,17 @@ void blk_timeout_work(struct work_struct *work)
*/
void blk_abort_request(struct request *req)
{
- if (blk_mark_rq_complete(req))
- return;
-
if (req->q->mq_ops) {
- blk_mq_rq_timed_out(req, false);
+ /*
+ * All we need to ensure is that timeout scan takes place
+ * immediately and that scan sees the new timeout value.
+ * No need for fancy synchronizations.
+ */
+ req->deadline = jiffies;
+ mod_timer(&req->q->timeout, 0);
} else {
+ if (blk_mark_rq_complete(req))
+ return;
blk_delete_timer(req);
blk_rq_timed_out(req);
}
--
2.9.5
next prev parent reply other threads:[~2018-01-09 16:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-09 16:29 [PATCHSET v5] blk-mq: reimplement timeout handling Tejun Heo
2018-01-09 16:29 ` [PATCH 1/8] blk-mq: move hctx lock/unlock into a helper Tejun Heo
2018-01-09 16:29 ` [PATCH 2/8] blk-mq: protect completion path with RCU Tejun Heo
2018-01-09 16:29 ` [PATCH 3/8] blk-mq: replace timeout synchronization with a RCU and generation based scheme Tejun Heo
2018-01-09 16:29 ` [PATCH 4/8] blk-mq: use blk_mq_rq_state() instead of testing REQ_ATOM_COMPLETE Tejun Heo
2018-01-09 16:29 ` Tejun Heo [this message]
2018-01-09 16:29 ` [PATCH 6/8] blk-mq: remove REQ_ATOM_COMPLETE usages from blk-mq Tejun Heo
2018-01-09 16:29 ` [PATCH 7/8] blk-mq: remove REQ_ATOM_STARTED Tejun Heo
2018-01-09 16:29 ` [PATCH 8/8] blk-mq: rename blk_mq_hw_ctx->queue_rq_srcu to ->srcu Tejun Heo
2018-01-09 16:53 ` [PATCHSET v5] blk-mq: reimplement timeout handling Jens Axboe
2018-01-12 20:57 ` Bart Van Assche
2018-01-12 21:07 ` Jens Axboe
2018-01-12 21:19 ` Bart Van Assche
2018-01-12 21:55 ` Jens Axboe
2018-01-14 15:12 ` jianchao.wang
2018-01-14 15:45 ` Ming Lei
2018-01-12 21:55 ` Laurence Oberman
2018-01-13 12:39 ` Ming Lei
2018-01-13 14:45 ` Ming Lei
2018-01-13 17:59 ` Ming Lei
-- strict thread matches above, loose matches on Subject: below --
2018-01-08 19:15 [PATCHSET v4] " Tejun Heo
2018-01-08 19:15 ` [PATCH 5/8] blk-mq: make blk_abort_request() trigger timeout path Tejun Heo
2018-01-08 22:10 ` Bart Van Assche
2018-01-09 16:02 ` tj
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