Re: [RFC PATCH] scripts: checkpatch.pl: remove obsolete in_atomic rule

[Yang Shi]

On 11/6/17 5:52 AM, Michal Hocko wrote:
> On Sat 04-11-17 03:08:06, 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.
>
> NAK. in_atomic is tricky and shouldn't be used. I would bet most of the
> usage is simply broken. See more http://lkml.kernel.org/r/20171106100558.GD3165@xxxxxxxxxxxxxxxxxxxxxx

Thanks for following up. Yes, it sounds so. However, there is not a 
reliable and effective approach to check atomic context for both PREEMPT 
and !PREEMPT.

Yang

>   
> > Signed-off-by: Yang Shi <yang.s@xxxxxxxxxxxxxxx>
> > CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > ---
> > 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)?/) {
> > --
> > 1.8.3.1