From: Daniel Wagner <wagi@kernel.org>
To: Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@kernel.dk>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
James Smart <james.smart@broadcom.com>,
Hannes Reinecke <hare@suse.de>,
Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
Daniel Wagner <wagi@kernel.org>
Subject: [PATCH 0/2] nvme-fc: fix schedule in atomic context
Date: Fri, 14 Feb 2025 09:02:02 +0100 [thread overview]
Message-ID: <20250214-nvme-fc-fixes-v1-0-7a05d557d5cc@kernel.org> (raw)
Shinichiro reported [1] the recent change in the nvme-fc setup path [2]
introduced a bug. I didn't spot the schedule call in
nvme_change_ctrl_state.
It turns out the locking is not necessary if we make the state machine a
bit more restrictive and only allow entering the LIVE state from
CONNECTING. If we do this, it's possible to ensure we either enter LIVE
only if there was no connection loss event. Also the connection loss
event handler should always trigger the reset handler to avoid a
read-write race on the state machine state variable.
I've tried to replicate the original problem once again and wrote a new
blktest which tries to trigger the race condition. I let it run a for a
while and nothing broke, but I can't be sure it is really gone. The rest
of the blktests also passed. Unfortunatly, the test box with FC hardware
is currently not working, so I can't test this with real hardware.
[1] https://lore.kernel.org/all/denqwui6sl5erqmz2gvrwueyxakl5txzbbiu3fgebryzrfxunm@iwxuthct377m/
[2] https://lore.kernel.org/all/20250109-nvme-fc-handle-com-lost-v4-3-fe5cae17b492@kernel.org/
Signed-off-by: Daniel Wagner <wagi@kernel.org>
---
Daniel Wagner (2):
nvme: only allow entering LIVE from CONNECTING state
nvme-fc: rely on state transitions to handle connectivity loss
drivers/nvme/host/core.c | 2 --
drivers/nvme/host/fc.c | 67 +++++-------------------------------------------
2 files changed, 6 insertions(+), 63 deletions(-)
---
base-commit: a64dcfb451e254085a7daee5fe51bf22959d52d3
change-id: 20250213-nvme-fc-fixes-eda1a10def35
Best regards,
--
Daniel Wagner <wagi@kernel.org>
next reply other threads:[~2025-02-14 8:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-14 8:02 Daniel Wagner [this message]
2025-02-14 8:02 ` [PATCH 1/2] nvme: only allow entering LIVE from CONNECTING state Daniel Wagner
2025-02-20 10:34 ` Sagi Grimberg
2025-02-14 8:02 ` [PATCH 2/2] nvme-fc: rely on state transitions to handle connectivity loss Daniel Wagner
2025-02-20 10:36 ` Sagi Grimberg
2025-02-20 8:00 ` [PATCH 0/2] nvme-fc: fix schedule in atomic context Daniel Wagner
2025-02-20 12:50 ` Shinichiro Kawasaki
2025-02-20 17:23 ` Keith Busch
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