netdev - Re: [PATCH] net: mvneta: fix changing MTU when using per-cpu processing

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Date:	Fri, 1 Apr 2016 15:22:54 +0200
From:	Marcin Wojtas <mw@...ihalf.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	Andrew Lunn <andrew@...n.ch>,
	Jason Cooper <jason@...edaemon.net>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Gregory Clément 
	<gregory.clement@...e-electrons.com>, nadavh@...vell.com,
	Lior Amsalem <alior@...vell.com>,
	Sebastian Careba <nitroshift@...oo.com>,
	Marcin Wojtas <mw@...ihalf.com>,
	Grzegorz Jaszczyk <jaz@...ihalf.com>
Subject: Re: [PATCH] net: mvneta: fix changing MTU when using per-cpu processing

Hi David,

I've just realized I forgot to add an information, that this patch is
intended for 'net' tree.

Best regards,
Marcin

2016-04-01 15:21 GMT+02:00 Marcin Wojtas <mw@...ihalf.com>:
> After enabling per-cpu processing it appeared that under heavy load
> changing MTU can result in blocking all port's interrupts and transmitting
> data is not possible after the change.
>
> This commit fixes above issue by disabling percpu interrupts for the
> time, when TXQs and RXQs are reconfigured.
>
> Signed-off-by: Marcin Wojtas <mw@...ihalf.com>
> ---
>  drivers/net/ethernet/marvell/mvneta.c | 30 ++++++++++++++++--------------
>  1 file changed, 16 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index fee6a91..a433de9 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -3083,6 +3083,20 @@ static int mvneta_check_mtu_valid(struct net_device *dev, int mtu)
>         return mtu;
>  }
>
> +static void mvneta_percpu_enable(void *arg)
> +{
> +       struct mvneta_port *pp = arg;
> +
> +       enable_percpu_irq(pp->dev->irq, IRQ_TYPE_NONE);
> +}
> +
> +static void mvneta_percpu_disable(void *arg)
> +{
> +       struct mvneta_port *pp = arg;
> +
> +       disable_percpu_irq(pp->dev->irq);
> +}
> +
>  /* Change the device mtu */
>  static int mvneta_change_mtu(struct net_device *dev, int mtu)
>  {
> @@ -3107,6 +3121,7 @@ static int mvneta_change_mtu(struct net_device *dev, int mtu)
>          * reallocation of the queues
>          */
>         mvneta_stop_dev(pp);
> +       on_each_cpu(mvneta_percpu_disable, pp, true);
>
>         mvneta_cleanup_txqs(pp);
>         mvneta_cleanup_rxqs(pp);
> @@ -3130,6 +3145,7 @@ static int mvneta_change_mtu(struct net_device *dev, int mtu)
>                 return ret;
>         }
>
> +       on_each_cpu(mvneta_percpu_enable, pp, true);
>         mvneta_start_dev(pp);
>         mvneta_port_up(pp);
>
> @@ -3283,20 +3299,6 @@ static void mvneta_mdio_remove(struct mvneta_port *pp)
>         pp->phy_dev = NULL;
>  }
>
> -static void mvneta_percpu_enable(void *arg)
> -{
> -       struct mvneta_port *pp = arg;
> -
> -       enable_percpu_irq(pp->dev->irq, IRQ_TYPE_NONE);
> -}
> -
> -static void mvneta_percpu_disable(void *arg)
> -{
> -       struct mvneta_port *pp = arg;
> -
> -       disable_percpu_irq(pp->dev->irq);
> -}
> -
>  /* Electing a CPU must be done in an atomic way: it should be done
>   * after or before the removal/insertion of a CPU and this function is
>   * not reentrant.
> --
> 1.8.3.1
>