On 3/18/24 14:34, Ming Lei wrote:
On Mon, Mar 18, 2024 at 12:52:33PM +0000, Pavel Begunkov wrote:
On 3/18/24 08:16, Ming Lei wrote:
On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote:
uring_cmd implementations should not try to guess issue_flags, just use
a newly added io_uring_cmd_complete(). We're loosing an optimisation in
the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption
is that we don't care that much about it.
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
drivers/block/ublk_drv.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index bea3d5cf8a83..97dceecadab2 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq)
return true;
}
-static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io,
- unsigned int issue_flags)
+static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io)
{
bool done;
@@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io,
spin_unlock(&ubq->cancel_lock);
if (!done)
- io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags);
+ io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0);
}
/*
* The ublk char device won't be closed when calling cancel fn, so both
* ublk device and queue are guaranteed to be live
*/
-static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd,
- unsigned int issue_flags)
+static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd)
{
struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
struct ublk_queue *ubq = pdu->ubq;
@@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd,
io = &ubq->ios[pdu->tag];
WARN_ON_ONCE(io->cmd != cmd);
- ublk_cancel_cmd(ubq, io, issue_flags);
+ ublk_cancel_cmd(ubq, io);
.cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't
be removed, otherwise double task run is caused because .cancel_fn
can be called multiple times if the request stays in ctx->cancelable_uring_cmd.
I see, that's exactly why I was asking whether it can be deferred
to tw. Let me see if I can get by without that patch, but honestly
it's a horrible abuse of the ring state. Any ideas how that can be
cleaned up?
Simply deferring io_uring_cmd_done() in ublk_cancel_cmd() to tw still triggers
warning in __put_task_struct(), so I'd suggest to add the patch until
it is root-cause & fixed.
I mean drop the patch[es] changing how ublk passes issue_flags
around, moving cancellation point and all related, and leave it
to later really hoping we'll figure how to do it better.
--
Pavel Begunkov
