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ublk: reset the FETCH round under ub->mutex

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The release work resets the FETCH round without ub->mutex, while
START_DEV checks it under ub->mutex:

  START_DEV (ub->mutex)               release work
  all queues ready? yes
  ublksrv_tgid matches? yes
                                      ublk_reset_ch_dev():
                                        io->cmd = NULL, nr_queue_ready = 0
  go live: a request then reaches ublk_queue_cmd() with a NULL io->cmd

Do the reset under ub->mutex. Then START_DEV sees the round either ready
or reset. The work already takes ub->mutex when there is a disk, after
it has aborted the requests; nothing holding ub->mutex waits for it.

Fixes: 728cbac5fe ("ublk: move device reset into ublk_ch_release()")
Cc: stable@vger.kernel.org
Tested-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Link: https://patch.msgid.link/20261011063555.1142277-6-tom.leiming@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2026-10-11 01:35:48 -05:00 committed by Jens Axboe
parent f06ca594ea
commit 84824afdb5
1 changed files with 10 additions and 6 deletions
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16
drivers/block/ublk_drv.c
View File

@ -2556,8 +2556,10 @@ static void ublk_ch_release_work_fn(struct work_struct *work)
* reset, so that a new server can fetch and start the device.
*/
disk = ublk_get_disk(ub);
if (!disk)
if (!disk) {
mutex_lock(&ub->mutex);
goto reset;
}
/*
* All uring_cmd are done now, so abort any request outstanding to
@ -2589,7 +2591,7 @@ static void ublk_ch_release_work_fn(struct work_struct *work)
/* double check after grabbing lock */
if (!ub->ub_disk)
goto unlock;
goto reset;
/*
* Transition the device to the nosrv state. What exactly this
@ -2615,12 +2617,14 @@ static void ublk_ch_release_work_fn(struct work_struct *work)
WRITE_ONCE(ublk_get_queue(ub, i)->fail_io, true);
}
}
unlock:
reset:
/*
* All uring_cmd has been done now, reset device & ubq. Under
* ub->mutex, so START_DEV sees the round either ready or reset.
*/
ublk_reset_ch_dev(ub);
mutex_unlock(&ub->mutex);
ublk_put_disk(disk);
reset:
/* all uring_cmd has been done now, reset device & ubq */
ublk_reset_ch_dev(ub);
clear_bit(UB_STATE_OPEN, &ub->state);
/* put the reference grabbed in ublk_ch_release() */