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Date: Thu, 6 Aug 2026 06:49:58 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: io-uring@vger.kernel.org, Pavel Begunkov <asml.silence@gmail.com>,
 netdev@vger.kernel.org
Subject: Re: [PATCH io_uring-7.2 1/1] io_uring/zcrx: fail non-qops netdevs
 early
Message-ID: <20260806064958.1b9ae431@kernel.org>
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On Thu, 06 Aug 2026 06:00:49 -0600 Jens Axboe wrote:
> On Thu, 06 Aug 2026 12:42:33 +0100, Pavel Begunkov wrote:
> > netdev_get_by_index_lock() might return a netdev that doesn't have qops
> > and also relies on rtnl. We're going to reject it later when opening a
> > queue, but netdev_queue_get_dma_dev() warns before that. Reject non-qops
> > netdevs earlier for now.
> > 
> > RTNL: assertion failed at ./include/net/netdev_lock.h (72)
> > WARNING: ./include/net/netdev_lock.h:72 at netdev_assert_locked_ops_compat
> >     include/net/netdev_lock.h:72 [inline]
> > WARNING: ./include/net/netdev_lock.h:72 at netdev_queue_get_dma_dev+0x52e/0x660
> >     net/core/netdev_queues.c:43,
> > RIP: 0010:netdev_assert_locked_ops_compat include/net/netdev_lock.h:72 [inline]
> > RIP: 0010:netdev_queue_get_dma_dev+0x53a/0x660 net/core/netdev_queues.c:43
> > Call Trace:
> >  <TASK>
> >  zcrx_register_netdev io_uring/zcrx.c:831 [inline]
> >  io_register_zcrx+0xe94/0x1d30 io_uring/zcrx.c:983
> >  __io_uring_register io_uring/register.c:942 [inline]
> >  __do_sys_io_uring_register+0x1193/0x1bc0 io_uring/register.c:1040
> >  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> >  do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
> >  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> > 
> > [...]  
> 
> Applied, thanks!
> 
> [1/1] io_uring/zcrx: fail non-qops netdevs early
>       commit: cf7aa48151deb629022a8b0c61c139dbfa579933

I asked for a different fix :/

https://lore.kernel.org/all/20260805165817.7e1fc367@kernel.org/

Outside subsystems should not be poking at random fields and making
guesses. The assert is simply wrong and should be changed.

Jens, can you drop this please?