netdev - Re: [PATCH] r8169: Fix irq masking in rtl8169

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Message-ID: <20090318064010.GA13399@electric-eye.fr.zoreil.com>
Date:	Wed, 18 Mar 2009 07:40:11 +0100
From:	Francois Romieu <romieu@...zoreil.com>
To:	Karsten Wiese <fzu@...gehoertderstaat.de>
Cc:	netdev@...r.kernel.org, Rafael Wysocki <rjw@...k.pl>
Subject: Re: [PATCH] r8169: Fix irq masking in rtl8169_interrupt()

Karsten Wiese <fzu@...gehoertderstaat.de> :
> Am Dienstag 17 März 2009 schrieb Francois Romieu:
[...]
> > How the patch is supposed to work is not completely clear to me.
> 
> Without it, if netif_rx_schedule_prep() returns 0, __netif_rx_schedule() is not
> called so nothing is there to care for the transfer. Nonetheless intr_mask is 
> changed so that its not possible that __netif_rx_schedule() is ever called
> later.
> 
> Patch works by letting rtl8169_interrupt() again call netif_rx_schedule_prep()
> until it succeeds and __netif_rx_schedule() is called.

Thanks for the explanation.

If netif_rx_schedule fails after napi is enabled, there is a
racing poll thread to care for the transfer.

Stated differently the bug is noticeable because napi_enable() 
should be called before request_irq() in rtl8169_open, right ?

-- 
Ueimor
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