Messages in this thread Patch in this message | | | Date | Tue, 04 Jan 2022 09:26:18 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH] platform: finally disallow IRQ0 in platform_get_irq() and its ilk |
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[Adding Geert]
On Sat, 06 Nov 2021 20:26:47 +0000, Sergey Shtylyov <s.shtylyov@omp.ru> 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>
M.
-- Without deviation from the norm, progress is not possible.
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