From: Tao Chiu <taochiu@xxxxxxxxxxxx>
reset_work() in nvme-pci may hang forever in the following scenario:
1) A reset caused by a command timeout occurs due to a controller being
temporarily irresponsive.
2) nvme_reset_work() restarts admin queue at nvme_alloc_admin_tags(). At
the same time, a user-submitted admin command is queued and waiting
for completion. Then, reset_work() changes its state to CONNECTING,
and submits an identify command.
3) However, the controller does still not respond to any command,
causing a timeout being fired at the user-submitted command.
Unfortunately, nvme_timeout() does not see the completion on cq, and
any timeout that takes place under CONNECTING state causes a
controller shutdown.
4) Normally, the identify command in reset_work() would be canceled with
SC_HOST_ABORTED by nvme_dev_disable(), then reset_work can tear down
the controller accordingly. But the controller happens to return
online and respond the identify command before nvme_dev_disable()
should have been reaped it off.
5) reset_work() continues to setup_io_queues() as it observes no error
in init_identify(). However, the admin queue has already been
quiesced in dev_disable(). Thus, any following commands would be
blocked forever in blk_execute_rq().
This can be fixed by restricting usercmd commands when controller is not
in a LIVE state in nvme_queue_rq(), as what has been done previously in
fabrics.
```
nvme_reset_work(): |
nvme_alloc_admin_tags() |
| nvme_submit_user_cmd():
nvme_init_identify(): | ...
__nvme_submit_sync_cmd(): |
... | ...
---------------------------------------> nvme_timeout():
(Controller starts reponding commands) | nvme_dev_disable(, true):
nvme_setup_io_queues(): |
__nvme_submit_sync_cmd(): |
(hung in blk_execute_rq |
since run_hw_queue sees |
queue quiesced) |
```
Signed-off-by: Tao Chiu <taochiu@xxxxxxxxxxxx>
Signed-off-by: Cody Wong <codywong@xxxxxxxxxxxx>
Reviewed-by: Leon Chien <leonchien@xxxxxxxxxxxx>
---
drivers/nvme/host/pci.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 09d4c5f99fc3..a29b170701fc 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -933,6 +933,9 @@ static blk_status_t nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
if (unlikely(!test_bit(NVMEQ_ENABLED, &nvmeq->flags)))
return BLK_STS_IOERR;
+ if (!nvme_check_ready(&dev->ctrl, req, true))
+ return nvme_fail_nonready_command(&dev->ctrl, req);
+
ret = nvme_setup_cmd(ns, req);
if (ret)
return ret;
--
2.30.1
