Messages in this thread | | | Subject | Re: [PATCH] platform: finally disallow IRQ0 in platform_get_irq() and its ilk | From | Sergey Shtylyov <> | Date | Wed, 12 Jan 2022 23:08:53 +0300 |
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On 1/12/22 9:08 PM, Marc Zyngier 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)? > > Fixing SH would be a good thing.
Who argues with that? :-) However, I don't think it should be a pre-requisite for this patch, so that we have extra time until 5.17 final... actually, I had couple quick workarounds in mind; the problem however is that we don't seem to have the targets for testing... :-(
> Thanks, > > M.
MBR, Sergey
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