Re: [PATCH] Remove deprecated IRQF_DISABLED flag entirely

Valentin Rothberg
2015-03-05T13:41:57Z

On Thu, Mar 5, 2015 at 2:11 PM, Hannes Reinecke <hare@suse.de> wrote:
> On 03/05/2015 01:59 PM, Valentin Rothberg wrote:
>> The IRQF_DISABLED is a NOOP and has been scheduled for removal since
>> Linux v2.6.36 by commit 6932bf37bed4 ("genirq: Remove IRQF_DISABLED from
>> core code").
>>
>> According to commit e58aa3d2d0cc ("genirq: Run irq handlers with
>> interrupts disabled") running IRQ handlers with interrupts enabled can
>> cause stack overflows when the interrupt line of the issuing device is
>> still active.
>>
>> This patch ends the grace period for IRQF_DISABLED (i.e., SA_INTERRUPT
>> in older versions of Linux) and removes the definition and all remaining
>> usages of this flag.
>>
>> Signed-off-by: Valentin Rothberg <valentinrothberg@gmail.com>
>> ---
>> The bigger hunk in Documentation/scsi/ncr53c8xx.txt is removed entirely
>> as IRQF_DISABLED is gone now; the usage in older kernel versions
>> (including the old SA_INTERRUPT flag) should be discouraged. The
>> trouble of using IRQF_SHARED is a general problem and not specific to
>> any driver.
>>
>> I left the reference in Documentation/PCI/MSI-HOWTO.txt untouched since
>> it has already been removed in linux-next by commit b0e1ee8e1405
>> ("MSI-HOWTO.txt: remove reference on IRQF_DISABLED").
>>
>> All remaining references are changelogs that I suggest to keep.
>
> While you're at it: having '0x0' as a value for the irq flags looks
> a bit silly, and makes you wonder what the parameter is for.
>
> I would rather like to have
>
> #define IRQF_NONE 0x0
>
> and use it for these cases.
> That way the scope of that parameter is clear.

I like the idea. I checked the source code for such cases and passing
0 or 0x0 as IRQ flags appears quite often (also in the devm
counterparts).
If nobody is against your proposal, then I will prepare a Coccinelle
script that takes care of it and send it in a patch series (e.g.,
introduce definition of IRQF_NONE, the Coccinelle and following a big
patch that applies changes proposed by the script).

Kind regards,
Valentin