netdev - Re: [PATCH net v2] sfc: fix calling of free

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Date:	Fri, 09 May 2014 02:04:07 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Nikolay Aleksandrov <nikolay@...hat.com>
Cc:	netdev@...r.kernel.org, Zenghui Shi <zshi@...hat.com>,
	linux-net-drivers@...arflare.com,
	Shradha Shah <sshah@...arflare.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net v2] sfc: fix calling of free_irq with already free
 vector

On Thu, 2014-05-08 at 12:44 +0200, 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.

Oops, I think we had given up regular testing legacy interrupts by this
point as there seemed to be no real need for them.

> CC: Zenghui Shi <zshi@...hat.com>
> CC: Ben Hutchings <ben@...adent.org.uk>
> CC: <linux-net-drivers@...arflare.com>
> CC: Shradha Shah <sshah@...arflare.com>
> CC: David S. Miller <davem@...emloft.net>
> 
> Fixes: 1899c111a535 ("sfc: Fix IRQ cleanup in case of a probe failure")
> Reported-by: Zenghui Shi <zshi@...hat.com>
> Signed-off-by: Nikolay Aleksandrov <nikolay@...hat.com>
> ---
> 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..43761d3b8651 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->interrupt_mode != EFX_INT_MODE_LEGACY) {

Minor nit: this could use EFX_INT_MODE_USE_MSI(efx), same as in
efx_nic_init_interrupt().

> +		/* 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 */

Ben.

-- 
Ben Hutchings
Beware of programmers who carry screwdrivers. - Leonard Brandwein

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