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Mon, 13 Dec 2021 13:36:02 -0800 (PST) Received: from [10.225.54.48] (unknown [10.225.54.48]) by usg-ed-osssrv.wdc.com (Postfix) with ESMTPSA id 4JCZZ947Brz1RtVG; Mon, 13 Dec 2021 13:36:01 -0800 (PST) Message-ID: <0d967bb4-0b80-c293-b7d5-f49c9cc38718@opensource.wdc.com> Date: Tue, 14 Dec 2021 06:36:00 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved Content-Language: en-US To: Andy Shevchenko Cc: Sergey Shtylyov , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, Hans de Goede , Jens Axboe References: <20211209145937.77719-1-andriy.shevchenko@linux.intel.com> <549c1825-56e6-de9e-e109-77f0d06cfd0f@opensource.wdc.com> <5322dafd-86ad-a293-6005-29384cb96cc8@omp.ru> From: Damien Le Moal Organization: Western Digital In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/12/13 20:52, Andy Shevchenko wrote: > On Mon, Dec 13, 2021 at 07:39:31AM +0900, Damien Le Moal wrote: >> On 2021/12/11 19:25, Sergey Shtylyov wrote: >>> On 11.12.2021 2:45, Damien Le Moal wrote: > > ... > >>>>>> 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. >>>> >>>> Thinking more about this, shouldn't this change go into platform_get_irq() >>>> instead of platform_get_irq_optional() ? >>> >>> Why? platform_get_irq() currently just calls platform_get_irq_optional()... >>> >>>> The way I see it, I think that the intended behavior for >>>> platform_get_irq_optional() is: >>>> 1) If have IRQ, return it, always > 0 >>>> 2) If no IRQ, return 0 >>> >>> That does include the IRQ0 case, right? >> >> IRQ 0 being invalid, I think that case should be dealt with internally within >> platform_get_irq_optional() and warn/error return. IRQ 0 showing up would thus >> be case (3), an error. >> >>> >>>> 3) If error, return < 0 >>>> no ? >>> >>> I completely agree, I (after thinking a bit) have no issues with that... >>> >>>> And for platform_get_irq(), case (2) becomes an error. >>>> Is this the intended semantic ? >>> >>> I don't see how it's different from the current behavior. But we can do >>> that as well, I just don't see whether it's really better... >> >> The problem I see is that the current behavior is unclear: what does >> platform_get_irq_optional() returning 0 mean ? IRQ == 0 ? or "no IRQ" ? I think >> it should be the latter rather than the former. Note that the function could >> return ENOENT (or similar) for the "no IRQ" case. With that, case (2) goes away, >> but then I do not see any difference between platform_get_irq_optional() and >> platform_get_irq(). >> >> If the preferred API semantic is to allow returning IRQ 0 with a warning, then >> the kdoc comments of platform_get_irq_optional() and platform_get_irq() are >> totally broken, and the code for many drivers is probably wrong too. > > Yeah, what we need to do is that (roughly a roadmap): > - revisit callers of platform_get_irq_optional() to be prepared for > new behaviour > - rewrite platform_get_irq() to return -ENOENT > - rewrite platform_get_irq_optional() to return 0 on -ENOENT > > This is how other similar (i.e. _optional) APIs do. Sounds like a good plan to me. In the mean time though, your patch 1/2 should keep the "if (!irq)" test and return an error for that case. No ? -- Damien Le Moal Western Digital Research