Messages in this thread | | | Subject | Re: [PATCH] platform: finally disallow IRQ0 in platform_get_irq() and its ilk | From | Sergey Shtylyov <> | Date | Tue, 4 Jan 2022 15:23:50 +0300 |
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On 1/4/22 12:47 PM, Geert Uytterhoeven 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> > >>> --- 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. > > https://lore.kernel.org/all/CAMuHMdUg3=q7gyaVHP0XcYUOo3PQUUv8Hc8wp5faVQ+bTBpg4A@mail.gmail.com > > TL;DR: Probably only smsc911x Ethernet on the AP-SH4A-3A and > AP-SH4AD-0A boards, which should trigger the warning since v5.8.
Gr... indeed these use IRQ0 and should cause WARN. Do you have any idea how to avoid this?
>> 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> > > TBH, I don't see much point in this patch, as the WARN() has been > there since a while,
Yet there's WARN() -- which (at the end of day) should be avoided.
> and the end goal is to return zero instead of > -ENXIO for no interrupt, right?
I don't care that much about platform_get_irq_optional() (Andy does), I do care about its caller, platform_get_irq(). The end goal here is to avoid WARN() and avoid having to handle IRQ0 in this function's callers.
> Gr{oetje,eeting}s, > > Geert [...]
MBR, Sergey
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