From: Simon Horman <horms@kernel.org>
To: Jakub Kicinski <kuba@kernel.org>
Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com,
pabeni@redhat.com, andrew+netdev@lunn.ch, stable@vger.kernel.org,
syzbot+a78926bdac2adb52dc0e@syzkaller.appspotmail.com,
axboe@kernel.dk, io-uring@vger.kernel.org,
asml.silence@gmail.com
Subject: Re: [PATCH net] net: expect instance lock in netdev_queue_get_dma_dev()
Date: Mon, 10 Aug 2026 11:23:28 +0100 [thread overview]
Message-ID: <20260810102328.GR51943@horms.kernel.org> (raw)
In-Reply-To: <20260806225627.3998672-1-kuba@kernel.org>
On Thu, Aug 06, 2026 at 03:56:26PM -0700, Jakub Kicinski wrote:
> netdev_queue_get_dma_dev() uses "compat" locking assert which wants
> either the rtnl_lock or netdev instance lock. This is not right,
> the callers are taking the instance lock unconditionally. All entry
> points for queue config are purely instance locked.
>
> In other words the callers use netdev_get_by_index_lock(), not
> netdev_get_by_index_lock_ops_compat(). All the state we will
> access is effectively instance lock protected (it's const for
> devices which are not ops-locked).
>
> Update the assert to avoid false positive warnings.
>
> Cc: stable@vger.kernel.org
> Fixes: b6c5f9454ef34 ("io_uring/zcrx: call netdev_queue_get_dma_dev() under instance lock")
> Reported-by: syzbot+a78926bdac2adb52dc0e@syzkaller.appspotmail.com
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
next prev parent reply other threads:[~2026-08-10 10:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-06 22:56 [PATCH net] net: expect instance lock in netdev_queue_get_dma_dev() Jakub Kicinski
2026-08-10 10:23 ` Simon Horman [this message]
2026-08-10 10:27 ` Daniel Borkmann
2026-08-10 23:20 ` patchwork-bot+netdevbpf
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