Re: [PATCH] watchdog: ftwdt010_wdt: fix test for platform_get_irq() failure

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Le 12/08/2022 à 08:07, Dan Carpenter a écrit :
On Thu, Aug 11, 2022 at 10:52:13PM +0200, Christophe JAILLET wrote:
Le 11/08/2022 à 12:56, Dan Carpenter a écrit :
This code assumes that platform_get_irq() function returns zero on
failure.  In fact, platform_get_irq() never returns zero.  It returns
negative error codes or positive non-zero values on success.

Fixes: eca10ae6000d ("watchdog: add driver for Cortina Gemini watchdog")
Signed-off-by: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@xxxxxxxxxxxxxxxx>
---
   drivers/watchdog/ftwdt010_wdt.c | 2 +-
   1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/watchdog/ftwdt010_wdt.c b/drivers/watchdog/ftwdt010_wdt.c
index 21dcc7765688..02112fc264bd 100644
--- a/drivers/watchdog/ftwdt010_wdt.c
+++ b/drivers/watchdog/ftwdt010_wdt.c
@@ -156,7 +156,7 @@ static int ftwdt010_wdt_probe(struct platform_device *pdev)
   	}
   	irq = platform_get_irq(pdev, 0);
-	if (irq) {
+	if (irq > 0) {
   		ret = devm_request_irq(dev, irq, ftwdt010_wdt_interrupt, 0,
   				       "watchdog bark", gwdt);
   		if (ret)

Hi,
can't platform_get_irq() return 0?
All the paths in platform_get_irq() look like 0 is a valid value.

The other patches you just sent are "< 0 ==> error", so ">= 0 ==> valid"

Any reason here for >0?

It can't really be zero.  On some of the other patches there was a tests
failure and success.  So if we're testing for < 0 then a test for >= 0
felt more complete.

But here it was like, testing for > 0 won't break anything that isn't
already broken.  It's easier to review.

Somebody has a Coccinelle test for:

	irq = platform_get_irq(pdev, 0);
	if (!irq)
		return -ENODEV;

But I implemented it in Smatch just for fun.  It turns out people had
introduced a couple new bugs recently.  Also the it appears that their
Coccinelle test does not warn about for success tests like this one.
And there are still a bunch of test that do:

	if (irq <= 0)
		return irq ?: -ENODEV;

But testing for zero is dead code so I didn't bother cleaning it up.

regards,
dan carpenter


Got it, thanks.

CJ



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