From: Greg Ungerer <gerg@linux-m68k.org>
To: Finn Thain <fthain@telegraphics.com.au>
Cc: afzal mohammed <afzal.mohd.ma@gmail.com>,
linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Geert Uytterhoeven <geert@linux-m68k.org>
Subject: Re: [PATCH v2 06/18] m68k: Replace setup_irq() by request_irq()
Date: Wed, 26 Feb 2020 22:26:55 +1000 [thread overview]
Message-ID: <a682c89d-baf2-3d3c-647f-a07b2a146c9f@linux-m68k.org> (raw)
In-Reply-To: <alpine.LNX.2.22.394.2002261637400.8@nippy.intranet>
On 26/2/20 4:39 pm, Finn Thain wrote:
> On Wed, 26 Feb 2020, Greg Ungerer wrote:
>
>>> That error would almost always be -EBUSY, right?
>>
>> I expect it will never fail this early in boot.
>
> If so, it suggests to me that tweaking the error message string is just
> bikeshedding and that adding these error messages across the tree is just
> bloat.
>
>> But how will you know if it really is EBUSY if you don't print it out?
>>
>>> Moreover, compare this change,
>>>
>>> - setup_irq(TMR_IRQ_NUM, &m68328_timer_irq);
>>> + request_irq(TMR_IRQ_NUM, hw_tick, IRQF_TIMER, "timer", NULL);
>>>
>>> with this change,
>>>
>>> + int err;
>>>
>>> - setup_irq(TMR_IRQ_NUM, &m68328_timer_irq);
>>> + err = request_irq(TMR_IRQ_NUM, hw_tick, IRQF_TIMER, "timer", NULL);
>>> + if (err)
>>> + return err;
>>>
>>> Isn't the latter change the more common pattern? It prints nothing.
>>
>> Hmm, in my experience the much more common pattern is:
>>
>>> + int err;
>>>
>>> - setup_irq(TMR_IRQ_NUM, &m68328_timer_irq);
>>> + err = request_irq(TMR_IRQ_NUM, hw_tick, IRQF_TIMER, "timer", NULL);
>>> + if (err) {
>>> + pr_err("timer: request_irq() failed with err=%d\n", err);
>>> + return err;
>>> + }
>>
>> Where the pr_err() could be one of pr_err, printk, dev_err, ...
>>
>
> A rough poll using 'git grep' seems to agree with your assessment.
>
> If -EBUSY means the end user has misconfigured something, printing
> "request_irq failed" would be helpful. But does that still happen?
I have seen it many times. Its not at all difficult to get interrupt
assignments wrong, duplicated, or otherwise mistaken when creating
device trees. Not so much m68k/coldfire platforms where they are
most commonly hard coded.
> Printing any error message for -ENOMEM is frowned upon, and printing -12
> is really unhelpful. So the most popular pattern isn't that great, though
> it is usually less verbose than the example you've given.
>
> Besides, introducing local variables and altering control flow seems well
> out-of-scope for this kind of refactoring, right?
I don't agree with the local variable part. Adding a local variable to
keep track of the error return code doesn't seem out of scope for this change.
The patch as Afzal sent it doesn't change the control flow - and
that is the right thing to do here.
> Anyway, if you're going to add an error message,
> pr_err("%s: request_irq failed", foo) is unavoidable whenever foo isn't a
> string constant, so one can't expect to grep the source code for the
> literal error message from the log.
>
> BTW, one of the benefits of "%s: request_irq failed" is that a compilation
> unit with multiple request_irq calls permits the compiler to coalesce all
> duplicated format strings. Whereas, that's not possible with
> "foo: request_irq failed" and "bar: request_irq failed".
Given the wide variety of message text used with failed request_irq() calls
it would be shear luck that this matched anything else. A quick grep shows
that "%s: request_irq() failed\n" has no other exact matches in the current
kernel source.
Regards
Greg
next prev parent reply other threads:[~2020-02-26 12:27 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-24 0:47 [PATCH v2 00/18] genirq: Remove setup_irq() afzal mohammed
2020-02-24 0:48 ` [PATCH v2 01/18] alpha: replace setup_irq() by request_irq() afzal mohammed
2020-02-24 0:49 ` [PATCH v2 02/18] ARM: " afzal mohammed
2020-02-24 10:13 ` Lubomir Rintel
2020-02-26 16:31 ` Tony Lindgren
2020-02-24 0:49 ` [PATCH v2 03/18] c6x: " afzal mohammed
2020-02-24 0:49 ` [PATCH v2 04/18] hexagon: " afzal mohammed
2020-02-24 0:49 ` [PATCH v2 05/18] ia64: " afzal mohammed
2020-02-24 0:50 ` [PATCH v2 06/18] m68k: Replace " afzal mohammed
2020-02-26 0:42 ` Greg Ungerer
2020-02-26 1:11 ` Finn Thain
2020-02-26 2:11 ` Greg Ungerer
2020-02-26 6:39 ` Finn Thain
2020-02-26 12:26 ` Greg Ungerer [this message]
2020-02-26 22:31 ` Finn Thain
2020-02-27 6:37 ` Greg Ungerer
2020-02-27 22:19 ` Finn Thain
2020-02-27 8:18 ` afzal mohammed
2020-02-27 8:32 ` Geert Uytterhoeven
2020-02-27 12:06 ` afzal mohammed
2020-02-27 22:38 ` Finn Thain
2020-02-29 12:41 ` afzal mohammed
2020-02-28 7:05 ` Greg Ungerer
2020-02-29 12:47 ` afzal mohammed
2020-02-29 13:15 ` afzal mohammed
2020-02-29 23:11 ` Finn Thain
2020-03-01 1:05 ` afzal mohammed
2020-03-01 3:26 ` Finn Thain
2020-03-01 6:13 ` afzal mohammed
2020-03-02 6:26 ` Finn Thain
2020-03-04 1:24 ` afzal mohammed
2020-02-24 0:50 ` [PATCH v2 07/18] microblaze: " afzal mohammed
2020-02-24 0:50 ` [PATCH v2 08/18] MIPS: " afzal mohammed
2020-02-24 0:51 ` [PATCH v2 09/18] parisc: " afzal mohammed
2020-02-24 0:51 ` [PATCH v2 10/18] powerpc: " afzal mohammed
2020-02-24 0:51 ` [PATCH v2 11/18] s390: replace " afzal mohammed
2020-02-24 0:51 ` [PATCH v2 12/18] sh: " afzal mohammed
2020-02-24 0:52 ` [PATCH v2 13/18] unicore32: " afzal mohammed
2020-02-24 0:52 ` [PATCH v2 14/18] x86: Replace " afzal mohammed
2020-02-24 0:52 ` [PATCH v2 15/18] xtensa: replace " afzal mohammed
2020-02-24 0:52 ` [PATCH v2 16/18] clocksource: Replace " afzal mohammed
2020-02-25 2:52 ` kbuild test robot
2020-02-25 7:51 ` afzal mohammed
2020-02-27 10:59 ` [PATCH v3 " afzal mohammed
2020-02-27 11:18 ` Daniel Lezcano
2020-03-12 6:48 ` [PATCH v4] clocksource/drivers/timer-cs5535: request irq with non-NULL dev_id afzal mohammed
2020-03-12 7:10 ` afzal mohammed
2020-03-12 18:23 ` Daniel Lezcano
2020-03-19 8:47 ` [tip: timers/core] clocksource/drivers/timer-cs5535: Request " tip-bot2 for afzal mohammed
2020-02-24 0:53 ` [PATCH v2 17/18] irqchip: Replace setup_irq() by request_irq() afzal mohammed
2020-02-24 0:53 ` [PATCH v2 18/18] genirq: Remove setup_irq() and remove_irq() afzal mohammed
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