2022-11-11 08:23:51

by Christophe Leroy

Subject: [PATCH] ata: sata_dwc_460ex: Check !irq instead of irq == NO_IRQ

NO_IRQ is a relic from the old days. It is not used anymore in core
functions. By the way, function irq_of_parse_and_map() returns value 0
on error.

In some drivers, NO_IRQ is erroneously used to check the return of
irq_of_parse_and_map().

It is not a real bug today because the only architectures using the
drivers being fixed by this patch define NO_IRQ as 0, but there are
architectures which define NO_IRQ as -1. If one day those
architectures start using the non fixed drivers, there will be a
problem.

Long time ago Linus advocated for not using NO_IRQ, see
https://lkml.org/lkml/2005/11/21/221 . He re-iterated the same view
recently in https://lkml.org/lkml/2022/10/12/622

So test !irq instead of tesing irq == NO_IRQ.

Signed-off-by: Christophe Leroy <[email protected]>
---
drivers/ata/sata_dwc_460ex.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
index e3263e961045..5fb80ccde65b 100644
--- a/drivers/ata/sata_dwc_460ex.c
+++ b/drivers/ata/sata_dwc_460ex.c
@@ -242,7 +242,7 @@ static int sata_dwc_dma_init_old(struct platform_device *pdev,

/* Get SATA DMA interrupt number */
hsdev->dma->irq = irq_of_parse_and_map(np, 1);
- if (hsdev->dma->irq == NO_IRQ) {
+ if (!hsdev->dma->irq) {
dev_err(dev, "no SATA DMA irq\n");
return -ENODEV;
}
@@ -1180,7 +1180,7 @@ static int sata_dwc_probe(struct platform_device *ofdev)

/* Get SATA interrupt number */
irq = irq_of_parse_and_map(np, 0);
- if (irq == NO_IRQ) {
+ if (!irq) {
dev_err(dev, "no SATA DMA irq\n");
return -ENODEV;
}
--
2.37.1

2022-11-11 08:59:04

by Damien Le Moal

Subject: Re: [PATCH] ata: sata_dwc_460ex: Check !irq instead of irq == NO_IRQ

On 11/11/22 03:50, Christophe Leroy wrote:
> NO_IRQ is a relic from the old days. It is not used anymore in core
> functions. By the way, function irq_of_parse_and_map() returns value 0
> on error.
>
> In some drivers, NO_IRQ is erroneously used to check the return of
> irq_of_parse_and_map().
>
> It is not a real bug today because the only architectures using the
> drivers being fixed by this patch define NO_IRQ as 0, but there are
> architectures which define NO_IRQ as -1. If one day those
> architectures start using the non fixed drivers, there will be a
> problem.
>
> Long time ago Linus advocated for not using NO_IRQ, see
> https://lkml.org/lkml/2005/11/21/221 . He re-iterated the same view
> recently in https://lkml.org/lkml/2022/10/12/622
>
> So test !irq instead of tesing irq == NO_IRQ.
>
> Signed-off-by: Christophe Leroy <[email protected]>
> ---
> drivers/ata/sata_dwc_460ex.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
> index e3263e961045..5fb80ccde65b 100644
> --- a/drivers/ata/sata_dwc_460ex.c
> +++ b/drivers/ata/sata_dwc_460ex.c
> @@ -242,7 +242,7 @@ static int sata_dwc_dma_init_old(struct platform_device *pdev,
>
> /* Get SATA DMA interrupt number */
> hsdev->dma->irq = irq_of_parse_and_map(np, 1);
> - if (hsdev->dma->irq == NO_IRQ) {
> + if (!hsdev->dma->irq) {
> dev_err(dev, "no SATA DMA irq\n");
> return -ENODEV;
> }
> @@ -1180,7 +1180,7 @@ static int sata_dwc_probe(struct platform_device *ofdev)
>
> /* Get SATA interrupt number */
> irq = irq_of_parse_and_map(np, 0);
> - if (irq == NO_IRQ) {
> + if (!irq) {
> dev_err(dev, "no SATA DMA irq\n");
> return -ENODEV;
> }

You can also remove the:

#ifndef NO_IRQ

#define NO_IRQ 0

#endif

at the top of the file.

--
Damien Le Moal
Western Digital Research