[PATCH 6.6 005/143] ublk: move ublk_cancel_dev() out of ub->mutex

Greg Kroah-Hartman
2024-03-04T21:36:54Z

From: Ming Lei <ming.lei@redhat.com>

[ Upstream commit 85248d670b71d9edda9459ee14fdc85c8e9632c0 ]

ublk_cancel_dev() just calls ublk_cancel_queue() to cancel all pending
io commands after ublk request queue is idle. The only protection is just
the read & write of ubq->nr_io_ready and avoid duplicated command cancel,
so add one per-queue lock with cancel flag for providing this protection,
meantime move ublk_cancel_dev() out of ub->mutex.

Then we needn't to call io_uring_cmd_complete_in_task() to cancel
pending command. And the same cancel logic will be re-used for
cancelable uring command.

This patch basically reverts commit ac5902f84bb5 ("ublk: fix AB-BA lockdep warning").

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20231009093324.957829-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/block/ublk_drv.c | 40 +++++++++++++++++++++++-----------------
1 file changed, 23 insertions(+), 17 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 630ddfe6657bc..f4e0573c47114 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -115,6 +115,9 @@ struct ublk_uring_cmd_pdu {
*/
#define UBLK_IO_FLAG_NEED_GET_DATA 0x08

+/* atomic RW with ubq->cancel_lock */
+#define UBLK_IO_FLAG_CANCELED 0x80000000
+
struct ublk_io {
/* userspace buffer address from io cmd */
__u64 addr;
@@ -139,6 +142,7 @@ struct ublk_queue {
bool force_abort;
bool timeout;
unsigned short nr_io_ready; /* how many ios setup */
+ spinlock_t cancel_lock;
struct ublk_device *dev;
struct ublk_io ios[];
};
@@ -1477,28 +1481,28 @@ static inline bool ublk_queue_ready(struct ublk_queue *ubq)
return ubq->nr_io_ready == ubq->q_depth;
}

-static void ublk_cmd_cancel_cb(struct io_uring_cmd *cmd, unsigned issue_flags)
-{
- io_uring_cmd_done(cmd, UBLK_IO_RES_ABORT, 0, issue_flags);
-}
-
static void ublk_cancel_queue(struct ublk_queue *ubq)
{
int i;

- if (!ublk_queue_ready(ubq))
- return;
-
for (i = 0; i < ubq->q_depth; i++) {
struct ublk_io *io = &ubq->ios[i];

- if (io->flags & UBLK_IO_FLAG_ACTIVE)
- io_uring_cmd_complete_in_task(io->cmd,
- ublk_cmd_cancel_cb);
- }
+ if (io->flags & UBLK_IO_FLAG_ACTIVE) {
+ bool done;

- /* all io commands are canceled */
- ubq->nr_io_ready = 0;
+ spin_lock(&ubq->cancel_lock);
+ done = !!(io->flags & UBLK_IO_FLAG_CANCELED);
+ if (!done)
+ io->flags |= UBLK_IO_FLAG_CANCELED;
+ spin_unlock(&ubq->cancel_lock);
+
+ if (!done)
+ io_uring_cmd_done(io->cmd,
+ UBLK_IO_RES_ABORT, 0,
+ IO_URING_F_UNLOCKED);
+ }
+ }
}

/* Cancel all pending commands, must be called after del_gendisk() returns */
@@ -1545,7 +1549,6 @@ static void __ublk_quiesce_dev(struct ublk_device *ub)
blk_mq_quiesce_queue(ub->ub_disk->queue);
ublk_wait_tagset_rqs_idle(ub);
ub->dev_info.state = UBLK_S_DEV_QUIESCED;
- ublk_cancel_dev(ub);
/* we are going to release task_struct of ubq_daemon and resets
* ->ubq_daemon to NULL. So in monitor_work, check on ubq_daemon causes UAF.
* Besides, monitor_work is not necessary in QUIESCED state since we have
@@ -1568,6 +1571,7 @@ static void ublk_quiesce_work_fn(struct work_struct *work)
__ublk_quiesce_dev(ub);
unlock:
mutex_unlock(&ub->mutex);
+ ublk_cancel_dev(ub);
}

static void ublk_unquiesce_dev(struct ublk_device *ub)
@@ -1607,8 +1611,8 @@ static void ublk_stop_dev(struct ublk_device *ub)
put_disk(ub->ub_disk);
ub->ub_disk = NULL;
unlock:
- ublk_cancel_dev(ub);
mutex_unlock(&ub->mutex);
+ ublk_cancel_dev(ub);
cancel_delayed_work_sync(&ub->monitor_work);
}

@@ -1962,6 +1966,7 @@ static int ublk_init_queue(struct ublk_device *ub, int q_id)
void *ptr;
int size;

+ spin_lock_init(&ubq->cancel_lock);
ubq->flags = ub->dev_info.flags;
ubq->q_id = q_id;
ubq->q_depth = ub->dev_info.queue_depth;
@@ -2569,8 +2574,9 @@ static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
int i;

WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq)));
+
/* All old ioucmds have to be completed */
- WARN_ON_ONCE(ubq->nr_io_ready);
+ ubq->nr_io_ready = 0;
/* old daemon is PF_EXITING, put it now */
put_task_struct(ubq->ubq_daemon);
/* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */
--
2.43.0