On 1/4/22 12:26 PM, Marc Zyngier wrote:
[Adding Geert]
On Sat, 06 Nov 2021 20:26:47 +0000,
Sergey Shtylyov <s.shtylyov@xxxxxx> 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@xxxxxx>
---
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@xxxxxxxxxx>
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)?