2021-11-26 01:12:16

by Tang Bin

Subject: [PATCH] ptp: ixp46x: Fix error handling in ptp_ixp_probe()

In the function ptp_ixp_probe(), when get irq failed
after executing platform_get_irq(), the negative value
returned will not be detected here. So fix error handling
in this place.

Fixes: 9055a2f591629 ("ixp4xx_eth: make ptp support a platform driver")
Signed-off-by: Tang Bin <[email protected]>
---
drivers/net/ethernet/xscale/ptp_ixp46x.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/xscale/ptp_ixp46x.c b/drivers/net/ethernet/xscale/ptp_ixp46x.c
index 39234852e01b..c52e01d89e47 100644
--- a/drivers/net/ethernet/xscale/ptp_ixp46x.c
+++ b/drivers/net/ethernet/xscale/ptp_ixp46x.c
@@ -272,7 +272,7 @@ static int ptp_ixp_probe(struct platform_device *pdev)
ixp_clock.master_irq = platform_get_irq(pdev, 0);
ixp_clock.slave_irq = platform_get_irq(pdev, 1);
if (IS_ERR(ixp_clock.regs) ||
- !ixp_clock.master_irq || !ixp_clock.slave_irq)
+ (ixp_clock.master_irq < 0) || (ixp_clock.slave_irq < 0))
return -ENXIO;

ixp_clock.caps = ptp_ixp_caps;
--
2.18.2

2021-11-26 01:28:37

by Linus Walleij

Subject: Re: [PATCH] ptp: ixp46x: Fix error handling in ptp_ixp_probe()

On Fri, Nov 26, 2021 at 2:10 AM Tang Bin <[email protected]> wrote:

> In the function ptp_ixp_probe(), when get irq failed
> after executing platform_get_irq(), the negative value
> returned will not be detected here. So fix error handling
> in this place.
>
> Fixes: 9055a2f591629 ("ixp4xx_eth: make ptp support a platform driver")
> Signed-off-by: Tang Bin <[email protected]>

OK the intention is right but:

> - !ixp_clock.master_irq || !ixp_clock.slave_irq)
> + (ixp_clock.master_irq < 0) || (ixp_clock.slave_irq < 0))

Keep disallowing 0. Because that is not a valid IRQ.

... <= 0 ...

Yours,
Linus Walleij

2021-11-26 01:41:37

by Tang Bin

Subject: Re: [PATCH] ptp: ixp46x: Fix error handling in ptp_ixp_probe()

Hi

On 2021/11/26 9:26, Linus Walleij wrote:
> On Fri, Nov 26, 2021 at 2:10 AM Tang Bin <[email protected]> wrote:
>
>> In the function ptp_ixp_probe(), when get irq failed
>> after executing platform_get_irq(), the negative value
>> returned will not be detected here. So fix error handling
>> in this place.
>>
>> Fixes: 9055a2f591629 ("ixp4xx_eth: make ptp support a platform driver")
>> Signed-off-by: Tang Bin <[email protected]>
> OK the intention is right but:
>
>> - !ixp_clock.master_irq || !ixp_clock.slave_irq)
>> + (ixp_clock.master_irq < 0) || (ixp_clock.slave_irq < 0))
> Keep disallowing 0. Because that is not a valid IRQ.
>
> ... <= 0 ...

Please look at the function platform_get_irq() in the file
drivers/base/platform.c,

the example is :

    * int irq = platform_get_irq(pdev, 0);

    * if (irq < 0)

    *        return irq;

Thanks

Tang Bin

2021-11-26 23:12:09

by Linus Walleij

Subject: Re: [PATCH] ptp: ixp46x: Fix error handling in ptp_ixp_probe()

On Fri, Nov 26, 2021 at 2:40 AM tangbin <[email protected]> wrote:
> On 2021/11/26 9:26, Linus Walleij wrote:
> > On Fri, Nov 26, 2021 at 2:10 AM Tang Bin <[email protected]> wrote:
> >
> >> In the function ptp_ixp_probe(), when get irq failed
> >> after executing platform_get_irq(), the negative value
> >> returned will not be detected here. So fix error handling
> >> in this place.
> >>
> >> Fixes: 9055a2f591629 ("ixp4xx_eth: make ptp support a platform driver")
> >> Signed-off-by: Tang Bin <[email protected]>
> > OK the intention is right but:
> >
> >> - !ixp_clock.master_irq || !ixp_clock.slave_irq)
> >> + (ixp_clock.master_irq < 0) || (ixp_clock.slave_irq < 0))
> > Keep disallowing 0. Because that is not a valid IRQ.
> >
> > ... <= 0 ...
>
> Please look at the function platform_get_irq() in the file
> drivers/base/platform.c,
>
> the example is :
>
> * int irq = platform_get_irq(pdev, 0);
>
> * if (irq < 0)
>
> * return irq;

In this case, reading the code is a bad idea. IRQ 0 is not valid,
and the fact that platform_get_irq() can return 0 does not make
it valid.

See:
https://lwn.net/Articles/470820/

Yours,
Linus Walleij