Re: [PATCH net] i40e: fix IRQ freeing in i40e_vsi_request_irq_msix error path

[Subbaraya Sundeep <sbhatta@marvell.com>]

Hi Michal,

On 2025-08-18 at 15:39:03, Michal Schmidt (mschmidt@redhat.com) wrote:
> If request_irq() in i40e_vsi_request_irq_msix() fails in an iteration
> later than the first, the error path wants to free the IRQs requested
> so far. However, it uses the wrong dev_id argument for free_irq(), so
> it does not free the IRQs correctly and instead triggers the warning:
> 
>  Trying to free already-free IRQ 173
>  WARNING: CPU: 25 PID: 1091 at kernel/irq/manage.c:1829 __free_irq+0x192/0x2c0
>  Modules linked in: i40e(+) [...]
>  CPU: 25 UID: 0 PID: 1091 Comm: NetworkManager Not tainted 6.17.0-rc1+ #1 PREEMPT(lazy)
>  Hardware name: [...]
>  RIP: 0010:__free_irq+0x192/0x2c0
>  [...]
>  Call Trace:
>   <TASK>
>   free_irq+0x32/0x70
>   i40e_vsi_request_irq_msix.cold+0x63/0x8b [i40e]
>   i40e_vsi_request_irq+0x79/0x80 [i40e]
>   i40e_vsi_open+0x21f/0x2f0 [i40e]
>   i40e_open+0x63/0x130 [i40e]
>   __dev_open+0xfc/0x210
>   __dev_change_flags+0x1fc/0x240
>   netif_change_flags+0x27/0x70
>   do_setlink.isra.0+0x341/0xc70
>   rtnl_newlink+0x468/0x860
>   rtnetlink_rcv_msg+0x375/0x450
>   netlink_rcv_skb+0x5c/0x110
>   netlink_unicast+0x288/0x3c0
>   netlink_sendmsg+0x20d/0x430
>   ____sys_sendmsg+0x3a2/0x3d0
>   ___sys_sendmsg+0x99/0xe0
>   __sys_sendmsg+0x8a/0xf0
>   do_syscall_64+0x82/0x2c0
>   entry_SYSCALL_64_after_hwframe+0x76/0x7e
>   [...]
>   </TASK>
>  ---[ end trace 0000000000000000 ]---
> 
> Use the same dev_id for free_irq() as for request_irq().
> 
> I tested this with inserting code to fail intentionally.
> 
Nice. Looks like changing this in i40e_vsi_request_irq_msix was missed
during 493fb30011b3. Just a question isn't this not throwing any
compilation warning all these days?
Anyway LGTM.

Reviewed-by: Subbaraya Sundeep <sbhatta@marvell.com>

Thanks,
Sundeep

> Fixes: 493fb30011b3 ("i40e: Move q_vectors from pointer to array to array of pointers")
> Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index b83f823e4917..dd21d93d39dd 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -4156,7 +4156,7 @@ static int i40e_vsi_request_irq_msix(struct i40e_vsi *vsi, char *basename)
>  		irq_num = pf->msix_entries[base + vector].vector;
>  		irq_set_affinity_notifier(irq_num, NULL);
>  		irq_update_affinity_hint(irq_num, NULL);
> -		free_irq(irq_num, &vsi->q_vectors[vector]);
> +		free_irq(irq_num, vsi->q_vectors[vector]);
>  	}
>  	return err;
>  }
> -- 
> 2.50.1
>