From: Sergey Shtylyov <s.shtylyov@omp.ru>
To: Sergey Shtylyov <s.shtylyov@omp.ru>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Damien Le Moal <damien.lemoal@opensource.wdc.com>,
<linux-ide@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Hans de Goede <hdegoede@redhat.com>, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved
Date: Sat, 11 Dec 2021 13:13:52 +0300 [thread overview]
Message-ID: <8ec4a971-29ba-77f7-7c48-ad88decea70f@omp.ru> (raw)
In-Reply-To: <448ce97b-699d-bdab-b4e9-c9439fd81a85@gmail.com>
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
next prev parent reply other threads:[~2021-12-11 10:13 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-09 14:59 [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved Andy Shevchenko
2021-12-09 14:59 ` [PATCH v1 2/2] ata: libahci_platform: Remove bogus 32-bit DMA mask attempt Andy Shevchenko
2021-12-10 19:34 ` Andy Shevchenko
2021-12-11 0:04 ` Damien Le Moal
2021-12-17 0:58 ` Damien Le Moal
2021-12-17 11:57 ` Andy Shevchenko
2021-12-09 15:21 ` [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved Hans de Goede
2021-12-09 17:24 ` Sergey Shtylyov
2021-12-09 17:42 ` Andy Shevchenko
2021-12-09 18:22 ` Sergey Shtylyov
2021-12-09 19:22 ` Andy Shevchenko
2021-12-09 19:27 ` Andy Shevchenko
2021-12-09 20:31 ` Sergey Shtylyov
2021-12-09 20:29 ` Sergey Shtylyov
2021-12-10 10:44 ` Andy Shevchenko
2021-12-10 11:14 ` Sergey Shtylyov
2021-12-10 11:28 ` Andy Shevchenko
2021-12-10 17:39 ` Sergey Shtylyov
2021-12-10 17:51 ` Andy Shevchenko
2021-12-09 22:49 ` Damien Le Moal
2021-12-09 22:57 ` Damien Le Moal
2021-12-10 8:47 ` Andy Shevchenko
2021-12-10 16:38 ` Sergey Shtylyov
2021-12-10 17:57 ` Andy Shevchenko
2021-12-10 8:59 ` Sergey Shtylyov
2021-12-10 10:46 ` Andy Shevchenko
2021-12-10 11:19 ` Sergey Shtylyov
2021-12-10 11:36 ` Andy Shevchenko
2021-12-10 17:15 ` Sergei Shtylyov
2021-12-10 17:59 ` Andy Shevchenko
2021-12-10 19:01 ` Sergey Shtylyov
2021-12-10 19:25 ` Andy Shevchenko
2021-12-10 19:30 ` Sergey Shtylyov
2021-12-10 19:35 ` Sergei Shtylyov
2021-12-11 10:13 ` Sergey Shtylyov [this message]
2021-12-13 11:26 ` Andy Shevchenko
2021-12-10 23:45 ` Damien Le Moal
2021-12-11 10:25 ` Sergey Shtylyov
2021-12-12 22:39 ` Damien Le Moal
2021-12-13 11:52 ` Andy Shevchenko
2021-12-13 21:36 ` Damien Le Moal
2021-12-13 22:02 ` Andy Shevchenko
2021-12-13 11:49 ` Andy Shevchenko
2021-12-13 11:46 ` Andy Shevchenko
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