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SubjectRe: [PATCH] platform: finally disallow IRQ0 in platform_get_irq() and its ilk
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On 1/12/22 9:19 PM, Greg Kroah-Hartman wrote:

[...]
>>>> The commit a85a6c86c25b ("driver core: platform: Clarify that IRQ 0 is
>>>> invalid") only calls WARN() when IRQ0 is about to be returned, however
>>>> using IRQ0 is considered invalid (according to Linus) outside the arch/
>>>> code where it's used by the i8253 drivers. Many driver subsystems treat
>>>> 0 specially (e.g. as an indication of the polling mode by libata), so
>>>> the users of platform_get_irq[_byname]() in them would have to filter
>>>> out IRQ0 explicitly and this (quite obviously) doesn't scale...
>>>> Let's finally get this straight and return -EINVAL instead of IRQ0!
>>>>
>>>> Fixes: a85a6c86c25b ("driver core: platform: Clarify that IRQ 0 is invalid")
>>>> Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
>>>>
>>>> ---
>>>> The patch is against the 'driver-core-linus' branch of Greg Kroah-Hartman's
>>>> 'driver-core.git' repo.
>>>>
>>>> drivers/base/platform.c | 6 ++++--
>>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>>>
>>>> Index: driver-core/drivers/base/platform.c
>>>> ===================================================================
>>>> --- driver-core.orig/drivers/base/platform.c
>>>> +++ driver-core/drivers/base/platform.c
>>>> @@ -231,7 +231,8 @@ int platform_get_irq_optional(struct pla
>>>> out_not_found:
>>>> ret = -ENXIO;
>>>> out:
>>>> - WARN(ret == 0, "0 is an invalid IRQ number\n");
>>>> + if (WARN(!ret, "0 is an invalid IRQ number\n"))
>>>> + return -EINVAL;
>>>> return ret;
>>>> }
>>>> EXPORT_SYMBOL_GPL(platform_get_irq_optional);
>>>> @@ -445,7 +446,8 @@ static int __platform_get_irq_byname(str
>>>>
>>>> r = platform_get_resource_byname(dev, IORESOURCE_IRQ, name);
>>>> if (r) {
>>>> - WARN(r->start == 0, "0 is an invalid IRQ number\n");
>>>> + if (WARN(!r->start, "0 is an invalid IRQ number\n"))
>>>> + return -EINVAL;
>>>> return r->start;
>>>> }
>>>
>>> Geert recently mentioned that a few architectures (such as sh?) still
>>> use IRQ0 as something valid in limited cases.
>>>
>>> From my PoV, this patch is fine, but please be prepared to fix things
>>> in a couple of years when someone decides to boot a recent kernel on
>>> their pet dinosaur. With that in mind:
>>>
>>> Acked-by: Marc Zyngier <maz@kernel.org>
>>
>> Greg, so would that ACK be enough? Is there a chance this patch gets finally included
>> into 5.17-rc1? Or should I look into fixing the recently found arch/sh/ issue 1st (as you
>> can see, just WARN()'ing about IRQ0 wasn't enough to get this fixed)?
>
> 5.17-rc1 is way too late, sorry.

That's too bad...

> It would have had to be in my tree
> early last week to make it there,

Marc's ACK was posted on January 4th, early last week in my calendar! ;-)

> my pull requests are already sent to
> Linus.

Ah! Too bad.

> Please fix this up properly, and resend the correct patch series, there
> is no rush.

What series do you mean here, 2-patch series based atop of this patch?

> thanks,
>
> greg k-h

MBR, Sergey

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