public inbox for [email protected]
 help / color / mirror / Atom feed
From: Ming Lei <[email protected]>
To: Jens Axboe <[email protected]>,
	[email protected], [email protected]
Cc: ZiyangZhang <[email protected]>,
	Ming Lei <[email protected]>
Subject: [PATCH 05/10] ublk: make sure ublk uring cmd handling is done in submitter task context
Date: Mon, 18 Sep 2023 12:11:01 +0800	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

In well-done ublk server implementation, ublk io command won't be
linked into any link chain. Meantime we are always handled in no-wait
style, so basically ublk uring cmd handling is always done in submitter
task context.

However, the server may set IOSQE_ASYNC, or io command is linked to one
chain mistakenly, then we may still run into io-wq context and
ctx->uring_lock isn't held.

So in case of IO_URING_F_UNLOCKED, schedule this command by
io_uring_cmd_complete_in_task to run it in submitter task. Then
ublk_ch_uring_cmd_local() is always called with context uring_lock held,
and we needn't to worry about sync among submission code path.

Signed-off-by: Ming Lei <[email protected]>
---
 drivers/block/ublk_drv.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 9b3c0b3dd36e..46d499d96ca3 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1810,7 +1810,8 @@ static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
 	return NULL;
 }
 
-static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
+static inline int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd,
+		unsigned int issue_flags)
 {
 	/*
 	 * Not necessary for async retry, but let's keep it simple and always
@@ -1824,9 +1825,28 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
 		.addr = READ_ONCE(ub_src->addr)
 	};
 
+	WARN_ON_ONCE(issue_flags & IO_URING_F_UNLOCKED);
+
 	return __ublk_ch_uring_cmd(cmd, issue_flags, &ub_cmd);
 }
 
+static void ublk_ch_uring_cmd_cb(struct io_uring_cmd *cmd,
+		unsigned int issue_flags)
+{
+	ublk_ch_uring_cmd_local(cmd, issue_flags);
+}
+
+static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
+{
+	/* well-implemented server won't run into unlocked */
+	if (unlikely(issue_flags & IO_URING_F_UNLOCKED)) {
+		io_uring_cmd_complete_in_task(cmd, ublk_ch_uring_cmd_cb);
+		return -EIOCBQUEUED;
+	}
+
+	return ublk_ch_uring_cmd_local(cmd, issue_flags);
+}
+
 static inline bool ublk_check_ubuf_dir(const struct request *req,
 		int ubuf_dir)
 {
-- 
2.40.1


  parent reply	other threads:[~2023-09-18  4:13 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-18  4:10 [PATCH 00/10] io_uring/ublk: exit notifier support Ming Lei
2023-09-18  4:10 ` [PATCH 01/10] io_uring: allocate ctx id and build map between id and ctx Ming Lei
2023-09-18  4:10 ` [PATCH 02/10] io_uring: pass io_uring_ctx->id to uring_cmd Ming Lei
2023-09-18  4:10 ` [PATCH 03/10] io_uring: support io_uring notifier for uring_cmd Ming Lei
2023-09-18  4:11 ` [PATCH 04/10] ublk: don't get ublk device reference in ublk_abort_queue() Ming Lei
2023-09-18  4:11 ` Ming Lei [this message]
2023-09-18  4:11 ` [PATCH 06/10] ublk: make sure that uring cmd aiming at same queue won't cross io_uring contexts Ming Lei
2023-09-18  4:11 ` [PATCH 07/10] ublk: rename mm_lock as lock Ming Lei
2023-09-18  4:11 ` [PATCH 08/10] ublk: quiesce request queue when aborting queue Ming Lei
2023-09-18  4:11 ` [PATCH 09/10] ublk: replace monitor work with uring_cmd exit notifier Ming Lei
2023-09-18  4:11 ` [PATCH 10/10] ublk: simplify aborting request Ming Lei
2023-09-18 12:54 ` [PATCH 00/10] io_uring/ublk: exit notifier support Jens Axboe
2023-09-18 13:24   ` Ming Lei
2023-09-18 14:15     ` Jens Axboe
2023-09-18 16:02       ` Ming Lei
2023-09-18 16:03         ` Jens Axboe

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox