Re: MSI interrupts and disable_irq

[Jeff Garzik]

Yinghai Lu wrote:
> On 9/28/07, Jeff Garzik <jgarzik@xxxxxxxxx> 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

Interested parties should try the forcedeth patches I just posted :)

	Jeff



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