netdev - Re: [PATCH net v2] bnxt_en: Fix lockdep warning during rmmod

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Message-ID: <bd92c1b7-a358-4737-8f23-30b185cbb8ef@linux.dev>
Date: Sun, 17 Aug 2025 14:21:34 +0100
From: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
To: Michael Chan <michael.chan@...adcom.com>, davem@...emloft.net
Cc: netdev@...r.kernel.org, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, andrew+netdev@...n.ch, pavan.chebbi@...adcom.com,
 andrew.gospodarek@...adcom.com, sdf@...ichev.me
Subject: Re: [PATCH net v2] bnxt_en: Fix lockdep warning during rmmod

On 16.08.2025 19:38, Michael Chan wrote:
> The commit under the Fixes tag added a netdev_assert_locked() in
> bnxt_free_ntp_fltrs().  The lock should be held during normal run-time
> but the assert will be triggered (see below) during bnxt_remove_one()
> which should not need the lock.  The netdev is already unregistered by
> then.  Fix it by calling netdev_assert_locked_or_invisible() which will
> not assert if the netdev is unregistered.
> 
> WARNING: CPU: 5 PID: 2241 at ./include/net/netdev_lock.h:17 bnxt_free_ntp_fltrs+0xf8/0x100 [bnxt_en]
> Modules linked in: rpcrdma rdma_cm iw_cm ib_cm configfs ib_core bnxt_en(-) bridge stp llc x86_pkg_temp_thermal xfs tg3 [last unloaded: bnxt_re]
> CPU: 5 UID: 0 PID: 2241 Comm: rmmod Tainted: G S      W           6.16.0 #2 PREEMPT(voluntary)
> Tainted: [S]=CPU_OUT_OF_SPEC, [W]=WARN
> Hardware name: Dell Inc. PowerEdge R730/072T6D, BIOS 2.4.3 01/17/2017
> RIP: 0010:bnxt_free_ntp_fltrs+0xf8/0x100 [bnxt_en]
> Code: 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 48 8b 47 60 be ff ff ff ff 48 8d b8 28 0c 00 00 e8 d0 cf 41 c3 85 c0 0f 85 2e ff ff ff <0f> 0b e9 27 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
> RSP: 0018:ffffa92082387da0 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff9e5b593d8000 RCX: 0000000000000001
> RDX: 0000000000000001 RSI: ffffffff83dc9a70 RDI: ffffffff83e1a1cf
> RBP: ffff9e5b593d8c80 R08: 0000000000000000 R09: ffffffff8373a2b3
> R10: 000000008100009f R11: 0000000000000001 R12: 0000000000000001
> R13: ffffffffc01c4478 R14: dead000000000122 R15: dead000000000100
> FS:  00007f3a8a52c740(0000) GS:ffff9e631ad1c000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055bb289419c8 CR3: 000000011274e001 CR4: 00000000003706f0
> Call Trace:
>   <TASK>
>   bnxt_remove_one+0x57/0x180 [bnxt_en]
>   pci_device_remove+0x39/0xc0
>   device_release_driver_internal+0xa5/0x130
>   driver_detach+0x42/0x90
>   bus_remove_driver+0x61/0xc0
>   pci_unregister_driver+0x38/0x90
>   bnxt_exit+0xc/0x7d0 [bnxt_en]
> 
> Fixes: 004b5008016a ("eth: bnxt: remove most dependencies on RTNL")
> Reviewed-by: Pavan Chebbi <pavan.chebbi@...adcom.com>
> Signed-off-by: Michael Chan <michael.chan@...adcom.com>
> ---
> v2: Use netdev_assert_locked_or_invisible()
> 
> v1: https://lore.kernel.org/netdev/20250815170823.4062508-1-michael.chan@broadcom.com/
> ---
>   drivers/net/ethernet/broadcom/bnxt/bnxt.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index 2800a90fba1f..207a8bb36ae5 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -5332,7 +5332,7 @@ static void bnxt_free_ntp_fltrs(struct bnxt *bp, bool all)
>   {
>   	int i;
>   
> -	netdev_assert_locked(bp->dev);
> +	netdev_assert_locked_or_invisible(bp->dev);
>   
>   	/* Under netdev instance lock and all our NAPIs have been disabled.
>   	 * It's safe to delete the hash table.

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@...ux.dev>