From: "Yang Shi" <yang.s@alibaba-inc.com>
To: Joe Perches <joe@perches.com>,
apw@canonical.com, Jonathan Corbet <corbet@lwn.net>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] scripts: checkpatch.pl: remove obsolete in_atomic rule
Date: Sat, 04 Nov 2017 06:41:29 +0800 [thread overview]
Message-ID: <46bcd443-cad5-beb6-10a0-bbdd1d38a70e@alibaba-inc.com> (raw)
In-Reply-To: <1509738092.15520.40.camel@perches.com>
On 11/3/17 12:41 PM, Joe Perches wrote:
> On Sat, 2017-11-04 at 03:08 +0800, Yang Shi wrote:
>> checkpatch.pl still reports the below in_atomic warning:
>>
>> WARNING: use of in_atomic() is incorrect outside core kernel code
>> + if (in_atomic())
>>
>> But, in_atomic() has been used outside kernel dir for a long time, and
>> even drivers. So, remove the obsolete rule even though they can be
>> ignored.
>
> Removing in_atomic() from checkpatch does not make sense
> without also updating include/linux/preempt.h
>
> Jonathon Corbet added this comment in
>
> commit 8c703d35fa91911dd92a18c31a718853f483ad80
> Author: Jonathan Corbet <corbet@lwn.net>
> Date: Fri Mar 28 14:15:49 2008 -0700
>
> in_atomic(): document why it is unsuitable for general use
>
> Discourage people from inappropriately using in_atomic()
>
> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> ---
> include/linux/hardirq.h | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
> index 49829988bfa0..897f723bd222 100644
> --- a/include/linux/hardirq.h
> +++ b/include/linux/hardirq.h
> @@ -72,6 +72,13 @@
> #define in_softirq() (softirq_count())
> #define in_interrupt() (irq_count())
>
> +/*
> + * Are we running in atomic context? WARNING: this macro cannot
> + * always detect atomic context; in particular, it cannot know about
> + * held spinlocks in non-preemptible kernels. Thus it should not be
This part looks changed. CONFIG_PREEMPT_COUNT might be enabled with
non-preemptible kernel, so that in_atomic() could know if kernel held
spinlocks or not.
Yang
> + * used in the general case to determine whether sleeping is possible.
> + * Do not use in_atomic() in driver code.
> + */
>
> Maybe he remembers why...
>
>> Signed-off-by: Yang Shi <yang.s@alibaba-inc.com>
>> CC: Andrew Morton <akpm@linux-foundation.org>
>> ---
>> Not sure if removing the obsolete rule is preferred by checkpatch.pl, anyway
>> it sounds not make sense to keep invalid rule.
>>
>> scripts/checkpatch.pl | 11 -----------
>> 1 file changed, 11 deletions(-)
>>
>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
>> index 8b80bac..e8cf94f 100755
>> --- a/scripts/checkpatch.pl
>> +++ b/scripts/checkpatch.pl
>> @@ -6231,17 +6231,6 @@ sub process {
>> "Using $1 should generally have parentheses around the comparison\n" . $herecurr);
>> }
>>
>> -# whine mightly about in_atomic
>> - if ($line =~ /\bin_atomic\s*\(/) {
>> - if ($realfile =~ m@^drivers/@) {
>> - ERROR("IN_ATOMIC",
>> - "do not use in_atomic in drivers\n" . $herecurr);
>> - } elsif ($realfile !~ m@^kernel/@) {
>> - WARN("IN_ATOMIC",
>> - "use of in_atomic() is incorrect outside core kernel code\n" . $herecurr);
>> - }
>> - }
>> -
>> # whine about ACCESS_ONCE
>> if ($^V && $^V ge 5.10.0 &&
>> $line =~ /\bACCESS_ONCE\s*$balanced_parens\s*(=(?!=))?\s*($FuncArg)?/) {
next prev parent reply other threads:[~2017-11-03 22:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-03 19:08 [RFC PATCH] scripts: checkpatch.pl: remove obsolete in_atomic rule Yang Shi
2017-11-03 19:41 ` Joe Perches
2017-11-03 22:41 ` Yang Shi [this message]
2017-11-06 13:52 ` Michal Hocko
2017-11-06 16:08 ` Yang Shi
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