Subject: Re: [PATCH net v3] sfc: fix calling of free_irq with already free vector

From: Shradha Shah <[email-masked]>
Date: Fri, 9 May 2014 10:25:21 +0100

On 09/05/14 10:11, Nikolay Aleksandrov wrote:
> If the sfc driver is in legacy interrupt mode (either explicitly by
> using interrupt_mode module param or by falling back to it) it will
> hit a warning at kernel/irq/manage.c because it will try to free an irq
> which wasn't allocated by it in the first place because the MSI(X) irqs are
> zero and it'll try to free them unconditionally. So fix it by checking if
> we're in legacy mode and freeing the appropriate irqs.
>
> CC: Zenghui Shi <[email-masked]>
> CC: Ben Hutchings <[email-masked]>
> CC: <[email-masked]>
> CC: Shradha Shah <[email-masked]>
> CC: David S. Miller <[email-masked]>
>
> Fixes: 1899c111a535 ("sfc: Fix IRQ cleanup in case of a probe failure")
> Reported-by: Zenghui Shi <[email-masked]>
> Signed-off-by: Nikolay Aleksandrov <[email-masked]>

Acked-by: Shradha Shah <[email-masked]>

> ---
> v3: Use the EFX_INT_MODE_USE_MSI macro instead of direct check
> as suggested by Ben
> v2: Change the fix to check for the interrupt mode and adjust the
> commit message.
>
>  drivers/net/ethernet/sfc/nic.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/sfc/nic.c b/drivers/net/ethernet/sfc/nic.c
> index 32d969e857f7..89b83e59e1dc 100644
> --- a/drivers/net/ethernet/sfc/nic.c
> +++ b/drivers/net/ethernet/sfc/nic.c
> @@ -156,13 +156,15 @@ void efx_nic_fini_interrupt(struct efx_nic *efx)
>       efx->net_dev->rx_cpu_rmap = NULL;
>  #endif
>
> -     /* Disable MSI/MSI-X interrupts */
> -     efx_for_each_channel(channel, efx)
> -             free_irq(channel->irq, &efx->msi_context[channel->channel]);
> -
> -     /* Disable legacy interrupt */
> -     if (efx->legacy_irq)
> +     if (EFX_INT_MODE_USE_MSI(efx)) {
> +             /* Disable MSI/MSI-X interrupts */
> +             efx_for_each_channel(channel, efx)
> +                     free_irq(channel->irq,
> +                              &efx->msi_context[channel->channel]);
> +     } else {
> +             /* Disable legacy interrupt */
>               free_irq(efx->legacy_irq, efx);
> +     }
>  }
>
>  /* Register dump */
>
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