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.

Cc: stable@vger.kernel.org
Fixes: 2d9e31b9412c ("dmaengine: moxart: remove NO_IRQ")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
Changes in v3:
- added missed changelog v2.
Changes in v2:
- added Cc stable line;
- added Fixes line.
---
 drivers/dma/moxart-dma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/moxart-dma.c b/drivers/dma/moxart-dma.c
index 66dc6d31b603..16dd3c5aba4d 100644
--- a/drivers/dma/moxart-dma.c
+++ b/drivers/dma/moxart-dma.c
@@ -568,7 +568,7 @@ static int moxart_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	irq = irq_of_parse_and_map(node, 0);
-	if (!irq) {
+	if (irq <= 0) {
 		dev_err(dev, "no IRQ resource\n");
 		return -EINVAL;
 	}
-- 
2.25.1

Hello Ma Ke,

On 2024/8/18 15:17:57 +0800, Ma Ke wrote:
>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.
>
>Cc: stable@vger.kernel.org
>Fixes: 2d9e31b9412c ("dmaengine: moxart: remove NO_IRQ")
>Signed-off-by: Ma Ke <make24@iscas.ac.cn>
>---
>Changes in v3:
>- added missed changelog v2.
>Changes in v2:
>- added Cc stable line;
>- added Fixes line.
>---
>  drivers/dma/moxart-dma.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/drivers/dma/moxart-dma.c b/drivers/dma/moxart-dma.c
>index 66dc6d31b603..16dd3c5aba4d 100644
>--- a/drivers/dma/moxart-dma.c
>+++ b/drivers/dma/moxart-dma.c
>@@ -568,7 +568,7 @@ static int moxart_probe(struct platform_device *pdev)
>               return -ENOMEM;
>
>       irq = irq_of_parse_and_map(node, 0);
>-      if (!irq) {
>+      if (irq <= 0) {

The ’irq‘ variable type here is ‘unsigned int, which will never be negative, :-)

>
>               dev_err(dev, "no IRQ resource\n");
>               return -EINVAL;
>       }
>--
>2.25.1
>
>

Thanks,
Luoxi

On Sun, Aug 18, 2024, at 09:17, Ma Ke wrote:
> 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.
>
> Cc: stable@vger.kernel.org
> Fixes: 2d9e31b9412c ("dmaengine: moxart: remove NO_IRQ")
> Signed-off-by: Ma Ke <make24@iscas.ac.cn>
> ---

This makes no sense to me, you explain why the current code is
correct and then change it to something wrong?

> diff --git a/drivers/dma/moxart-dma.c b/drivers/dma/moxart-dma.c
> index 66dc6d31b603..16dd3c5aba4d 100644
> --- a/drivers/dma/moxart-dma.c
> +++ b/drivers/dma/moxart-dma.c
> @@ -568,7 +568,7 @@ static int moxart_probe(struct platform_device *pdev)
>  		return -ENOMEM;
> 
>  	irq = irq_of_parse_and_map(node, 0);
> -	if (!irq) {
> +	if (irq <= 0) {
>  		dev_err(dev, "no IRQ resource\n");
>  		return -EINVAL;

The "if (!irq)" is clearly the intended check, as you explain
irq_of_parse_and_map() returns 0 on error.

      Arnd