linux-kernel - Re: [PATCH] of/irq: handle irq_of_parse_and

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Message-ID: <u4qlhdhmya5pwfboffbuvmgabmmpjxh6dfqptw65k5fiiaeqoy@pnmzj2lgh5z4>
Date: Wed, 4 Sep 2024 00:55:35 +0200
From: Andi Shyti <andi.shyti@...nel.org>
To: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Ma Ke <make24@...as.ac.cn>, jochen@...am.de, grant.likely@...aro.org, 
	thierry.reding@...il.com, rob.herring@...xeda.com, linuxppc-dev@...ts.ozlabs.org, 
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] of/irq: handle irq_of_parse_and_map() errors

On Tue, Sep 03, 2024 at 06:56:41PM GMT, Christophe Leroy wrote:
> Le 30/08/2024 à 16:21, Ma Ke a écrit :
> > Zero and negative number is not a valid IRQ for in-kernel code and the
> > irq_of_parse_and_map() function returns zero on error.  So this check for
> > valid IRQs should only accept values > 0.
> 
> unsigned int irq_of_parse_and_map(struct device_node *node, int index);
> 
> I can't see how an 'unsigned int' can be negative.

hehe... correct... even though looks like we are walking on a
slackline, relying too much that no one in the future, inside
irq_of_parse_and_map() (and various callers), someone will try to
fit an -ENOSOMETHING into the unsigned int.

I wouldn't mind something like this[*] to ensure I can sleep
soundly.

Thanks for the review,
Andi

[*]
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index cea8f6874b1fb..df44a8ffa6843 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -954,6 +954,8 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
 out:
        mutex_unlock(&domain->root->mutex);

+       BUG_ON(virq < 0);
+
        return virq;
 }
 EXPORT_SYMBOL_GPL(irq_create_fwspec_mapping);

> Christophe
> 
> > 
> > Cc: stable@...r.kernel.org
> > Fixes: f7578496a671 ("of/irq: Use irq_of_parse_and_map()")
> > Signed-off-by: Ma Ke <make24@...as.ac.cn>
> > ---
> >   drivers/i2c/busses/i2c-cpm.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c
> > index 4794ec066eb0..41e3c95c0ef7 100644
> > --- a/drivers/i2c/busses/i2c-cpm.c
> > +++ b/drivers/i2c/busses/i2c-cpm.c
> > @@ -435,7 +435,7 @@ static int cpm_i2c_setup(struct cpm_i2c *cpm)
> >   	init_waitqueue_head(&cpm->i2c_wait);
> >   	cpm->irq = irq_of_parse_and_map(ofdev->dev.of_node, 0);
> > -	if (!cpm->irq)
> > +	if (cpm->irq <= 0)
> >   		return -EINVAL;
> >   	/* Install interrupt handler. */