linux-kernel - Re: [PATCH] PCI/LINK: bw_notification: Do not leave interrupt handler NULL

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Date:   Wed, 20 Mar 2019 08:48:33 -0500
From:   "Alex G." <mr.nuke.me@...il.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     austin_bolen@...l.com, alex_gagniuc@...lteam.com,
        keith.busch@...el.com, Shyam_Iyer@...l.com, lukas@...ner.de,
        okaya@...nel.org, torvalds@...ux-foundation.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI/LINK: bw_notification: Do not leave interrupt handler
 NULL

On 3/20/19 8:46 AM, Bjorn Helgaas wrote:
> Hi Alexandru,
> 
> On Mon, Mar 18, 2019 at 08:12:04PM -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.
>>
>> Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
>> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@...il.com>
> 
> What's your thought regarding Lukas' comment?  If you do repost this,
> please add a Fixes: tag to help connect this with the initial commit.

I like Lukas's idea. I should have this re-posted by end of week, unless 
there's an urgency to get it out earlier.

Alex