On Fri, Dec 10, 2021 at 02:19:52PM +0300, Sergey Shtylyov wrote:

On 12/10/21 1:46 PM, Andy Shevchenko wrote:

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platform_get_irq() will print a message when it fails.
No need to repeat this.

While at it, drop redundant check for 0 as platform_get_irq() spills
out a big WARN() in such case.

The reason you should be able to remove the "if (!irq)" test is that
platform_get_irq() never returns 0. At least, that is what the function kdoc
says. But looking at platform_get_irq_optional(), which is called by
platform_get_irq(), the out label is:

	WARN(ret == 0, "0 is an invalid IRQ number\n");
	return ret;

So 0 will be returned as-is. That is rather weird. That should be fixed to
return -ENXIO:

	if (WARN(ret == 0, "0 is an invalid IRQ number\n"))
		return -ENXIO;
	return ret;

   My unmerged patch (https://marc.info/?l=linux-kernel&m=163623041902285) does this
but returns -EINVAL instead.

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Otherwise, I do not think that removing the "if (!irq)" hunk is safe. no ?

   Of course it isn't...

It's unsubstantiated statement. The vIRQ 0 shouldn't be returned by any of
those API calls.

   We do _not_ know what needs to be fixed, that's the problem, and that's why the WARN()
is there...

So, have you seen this warning (being reported) related to libahci_platform?
If no, what we are discussing about then? The workaround is redundant and
no need to have a dead code in the driver, really.

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If it is the case, go and fix them, no need to workaround
in each of the callers.

   There's a need to work around as long as IRQ0 ican be returned, otherwise
   we get partly functioning or non-functioning drivers...

You get them unfunctioning anyways and you get the big WARN() even before this
patch.


-- 
With Best Regards,
Andy Shevchenko