netdev - Re: [PATCH] Improvev netconsole support for RTL8139 NIC driver

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Message-ID: <47E9B39C.5010502@pobox.com>
Date:	Tue, 25 Mar 2008 22:23:24 -0400
From:	Jeff Garzik <jgarzik@...ox.com>
To:	yshi <yang.shi@...driver.com>
CC:	netdev@...r.kernel.org, linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Improvev netconsole support for RTL8139 NIC driver

yshi wrote:
> In current RTL8139 NIC driver, spin_lock()/spin_unlock() is used
> for irq handler. But for netconsole/netpoll, it prefers
> spin_lock_irqsave()/spin_unlcok_irqrestore(). So this patch fixed
> this problem to improve netconsole/netpoll support.
> 
> Signed-off-by: Yang Shi <yang.shi@...driver.com>
> ---
> b/drivers/net/8139too.c |    9 +++++++++
> 1 file changed, 9 insertions(+)
> ---
> 
> --- a/drivers/net/8139too.c
> +++ b/drivers/net/8139too.c
> @@ -2136,8 +2136,13 @@ static irqreturn_t rtl8139_interrupt (in
>        u16 status, ackstat;
>        int link_changed = 0; /* avoid bogus "uninit" warning */
>        int handled = 0;
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +       unsigned long flags;
> 
> +       spin_lock_irqsave (&tp->lock, flags);
> +#else
>        spin_lock (&tp->lock);
> +#endif
>        status = RTL_R16 (IntrStatus);
> 
>        /* shared irq? */
> @@ -2185,7 +2190,11 @@ static irqreturn_t rtl8139_interrupt (in
>                        RTL_W16 (IntrStatus, TxErr);
>        }
>  out:
> +#ifdef CONFIG_NET_POLL_CONTROLLER
> +       spin_unlock_irqrestore (&tp->lock, flags);
> +#else
>        spin_unlock (&tp->lock);
> +#endif

This is bogus -- you should never need to slow down the hot path in such 
a way.

Add a local_irq_save()/restore() to rtl8139_poll_controller() or a 
similar solution, putting the burden on the netpoll/netconsole layer.

	Jeff



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