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Message-ID: <86802c440710061043u6e51cd7q468346bd06b08657@mail.gmail.com>
Date: Sat, 6 Oct 2007 10:43:30 -0700
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Jeff Garzik" <jgarzik@pobox.com>
Subject: Re: MSI interrupts and disable_irq
Cc: "Ayaz Abdulla" <aabdulla@nvidia.com>,
       "Manfred Spraul" <manfred@colorfullife.com>,
       nedev <netdev@vger.kernel.org>,
       "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
       "David Miller" <davem@davemloft.net>,
       "Andrew Morton" <akpm@linux-foundation.org>
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On 9/28/07, Jeff Garzik <jgarzik@pobox.com> wrote:
> Ayaz Abdulla wrote:
> > I am trying to track down a forcedeth driver issue described by bug 9047
> > in bugzilla (2.6.23-rc7-git1 forcedeth w/ MCP55 oops under heavy load).
> > I added a patch to synchronize the timer handlers so that one handler
> > doesn't accidently enable the IRQ while another timer handler is running
> > (see attachment 'Add timer lock' in bug report) and for other processing
> > protection.
> >
> > However, the system still had an Oops. So I added a lock around the
> > nv_rx_process_optimized() and the Oops has not happened (see attachment
> > 'New patch for locking' in bug report). This would imply a
> > synchronization issue. However, the only callers of that function are
> > the IRQ handler and the timer handlers (in non-NAPI case). The timer
> > handlers  use disable_irq so that the IRQ handler does not contend with
> > them. It looks as if disable_irq is not working properly.
> >
> > This issue repros only with MSI interrupt and not legacy INTx
> > interrupts. Any ideas?
>
> (added linux-kernel to CC, since I think it's more of a general kernel
> issue)
>
I wonder if the race is between soft_timer for nv_do_nic_poll from
different CPUs

YH