Messages in this thread | | | Date | Sat, 11 Dec 2021 13:13:52 +0300 | Subject | Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved | From | Sergey Shtylyov <> |
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On 10.12.2021 22:35, Sergei Shtylyov wrote:
[...] >>>>>>>>>>>> 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. >>>>>>>>>> >>>>>>>>>>> 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? >>>>>> >>>>>> No (as if you need to really see this while it's obvious from the code review). >>>>>> >>>>>>> If no, what we are discussing about then? The workaround is redundant and >>>>>> >>>>>> I don't know. :-) Your arguments so far seem bogus (sorry! :-))... >>>>> >>>>> It seems you haven't got them at all. The problems of platform_get_irq() et al >>>>> shouldn't be worked around in the callers. >>>> >>>> I have clearly explained to you what I'm working around there. If that wasn't clear >>>> enough, I don't want to continue this talk anymore. Good luck with your patch (not this >>>> one). >>> >>> Good luck with yours, not the one that touches platform_get_irq_optional() though! >> >> Mmh, I'm not touching it any way that would break what your patch was trying to do, >> unless you've re-thopught that. It also shoudn't matter whose patch gets merged 1st >> other than some small adaptation). > > BTW, looking at [1], this comment is wrong: > > + * Return: non-zero IRQ number on success, negative error number on failure. > > It doesn't mention 0 which you return from this function.
Also, your commit log is wrong in the description of how to handle the result:
<< Now: ret = platform_get_irq_optional(...); if (ret != -ENXIO) return ret; // respect deferred probe if (ret > 0) ...we get an IRQ... >>
The (ret != -ENXIO) check also succeeds on the (positive) IRQ #s, so the following code becomes unreachable. :-/
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ed7027fdf4ec41ed6df6814956dc11860232a9d5
MBR, Sergey
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