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Message-ID: <69cf3037390c7d82365ab0f5f92d55bd88a2400a.camel@redhat.com>
Subject: Re: [PATCH net v1] mlxbf_gige: stop interface during shutdown
From: Paolo Abeni <pabeni@redhat.com>
To: David Thompson <davthompson@nvidia.com>, davem@davemloft.net, 
	edumazet@google.com, kuba@kernel.org, u.kleine-koenig@pengutronix.de, 
	leon@kernel.org
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Date: Thu, 28 Mar 2024 13:48:43 +0100
In-Reply-To: <20240325210929.25362-1-davthompson@nvidia.com>
References: <20240325210929.25362-1-davthompson@nvidia.com>
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On Mon, 2024-03-25 at 17:09 -0400, David Thompson wrote:
> The mlxbf_gige driver intermittantly encounters a NULL pointer
> exception while the system is shutting down via "reboot" command.
> The mlxbf_driver will experience an exception right after executing
> its shutdown() method.  One example of this exception is:
>=20
> Unable to handle kernel NULL pointer dereference at virtual address 00000=
00000000070
> Mem abort info:
>   ESR =3D 0x0000000096000004
>   EC =3D 0x25: DABT (current EL), IL =3D 32 bits
>   SET =3D 0, FnV =3D 0
>   EA =3D 0, S1PTW =3D 0
>   FSC =3D 0x04: level 0 translation fault
> Data abort info:
>   ISV =3D 0, ISS =3D 0x00000004
>   CM =3D 0, WnR =3D 0
> user pgtable: 4k pages, 48-bit VAs, pgdp=3D000000011d373000
> [0000000000000070] pgd=3D0000000000000000, p4d=3D0000000000000000
> Internal error: Oops: 96000004 [#1] SMP
> CPU: 0 PID: 13 Comm: ksoftirqd/0 Tainted: G S         OE     5.15.0-bf.6.=
gef6992a #1
> Hardware name: https://www.mellanox.com BlueField SoC/BlueField SoC, BIOS=
 4.0.2.12669 Apr 21 2023
> pstate: 20400009 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=3D--)
> pc : mlxbf_gige_handle_tx_complete+0xc8/0x170 [mlxbf_gige]
> lr : mlxbf_gige_poll+0x54/0x160 [mlxbf_gige]
> sp : ffff8000080d3c10
> x29: ffff8000080d3c10 x28: ffffcce72cbb7000 x27: ffff8000080d3d58
> x26: ffff0000814e7340 x25: ffff331cd1a05000 x24: ffffcce72c4ea008
> x23: ffff0000814e4b40 x22: ffff0000814e4d10 x21: ffff0000814e4128
> x20: 0000000000000000 x19: ffff0000814e4a80 x18: ffffffffffffffff
> x17: 000000000000001c x16: ffffcce72b4553f4 x15: ffff80008805b8a7
> x14: 0000000000000000 x13: 0000000000000030 x12: 0101010101010101
> x11: 7f7f7f7f7f7f7f7f x10: c2ac898b17576267 x9 : ffffcce720fa5404
> x8 : ffff000080812138 x7 : 0000000000002e9a x6 : 0000000000000080
> x5 : ffff00008de3b000 x4 : 0000000000000000 x3 : 0000000000000001
> x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
> Call trace:
>  mlxbf_gige_handle_tx_complete+0xc8/0x170 [mlxbf_gige]
>  mlxbf_gige_poll+0x54/0x160 [mlxbf_gige]
>  __napi_poll+0x40/0x1c8
>  net_rx_action+0x314/0x3a0
>  __do_softirq+0x128/0x334
>  run_ksoftirqd+0x54/0x6c
>  smpboot_thread_fn+0x14c/0x190
>  kthread+0x10c/0x110
>  ret_from_fork+0x10/0x20
> Code: 8b070000 f9000ea0 f95056c0 f86178a1 (b9407002)
> ---[ end trace 7cc3941aa0d8e6a4 ]---
> Kernel panic - not syncing: Oops: Fatal exception in interrupt
> Kernel Offset: 0x4ce722520000 from 0xffff800008000000
> PHYS_OFFSET: 0x80000000
> CPU features: 0x000005c1,a3330e5a
> Memory Limit: none
> ---[ end Kernel panic - not syncing: Oops: Fatal exception in interrupt ]=
---
>=20
> During system shutdown, the mlxbf_gige driver's shutdown() is always exec=
uted.
> However, the driver's stop() method will only execute if networking inter=
face
> configuration logic within the Linux distribution has been setup to do so=
.
>=20
> If shutdown() executes but stop() does not execute, NAPI remains enabled
> and this can lead to an exception if NAPI is scheduled while the hardware
> interface has only been partially deinitialized.
>=20
> The networking interface managed by the mlxbf_gige driver must be properl=
y
> stopped during system shutdown so that IFF_UP is cleared, the hardware
> interface is put into a clean state, and NAPI is fully deinitialized.
>=20
> Fixes: f92e1869d74e ("Add Mellanox BlueField Gigabit Ethernet driver")
> Signed-off-by: David Thompson <davthompson@nvidia.com>

LGTM, but it would be nice if someone else at nvidia could have a look.

Thanks!

Paolo