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Date:   Fri, 19 Apr 2019 16:25:48 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Alex Williamson <alex.williamson@redhat.com>
Cc:     Alexandru Gagniuc <mr.nuke.me@gmail.com>, austin_bolen@dell.com,
        alex_gagniuc@dellteam.com, keith.busch@intel.com,
        Shyam_Iyer@Dell.com, lukas@wunner.de, okaya@kernel.org,
        torvalds@linux-foundation.org, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] PCI/LINK: bw_notification: Do not leave interrupt
 handler NULL
Message-ID: <20190419212548.GA253261@google.com>
References: <20190320193504.GC251185@google.com>
 <20190323003700.7294-1-mr.nuke.me@gmail.com>
 <20190325222502.GC24180@google.com>
 <20190419150827.5040897e@x1.home>
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On Fri, Apr 19, 2019 at 03:08:27PM -0600, Alex Williamson wrote:
> On Mon, 25 Mar 2019 17:25:02 -0500, Bjorn Helgaas <helgaas@kernel.org> wrote:
> > On Fri, Mar 22, 2019 at 07:36:51PM -0500, Alexandru Gagniuc wrote:
> > > A threaded IRQ with a NULL handler does not work with level-triggered
> > > interrupts. request_threaded_irq() will return an error:
> > > 
> > >   genirq: Threaded irq requested with handler=NULL and !ONESHOT for irq 16
> > >   pcie_bw_notification: probe of 0000:00:1b.0:pcie010 failed with error -22
> > > 
> > > For level interrupts we need to silence the interrupt before exiting
> > > the IRQ handler, so just clear the PCI_EXP_LNKSTA_LBMS bit there.
> > > 
> > > Fixes: e8303bb7a75c ("PCI/LINK: Report degraded links via link bandwidth notification")
> > > Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> > > Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>  
> > 
> > Applied with the following subject line to for-linus for v5.1, thanks!
> > 
> >   PCI/LINK: Supply IRQ handler so level-triggered IRQs are acked
> 
> That made it a little tricky to track down this thread.

Yeah, sorry about that.  I've been wondering if I should add
lore.kernel.org URLs when I apply patches.  Maybe this is one good
reason to do that.

Bjorn