Messages in this thread | | | Date | Tue, 10 Oct 2017 17:41:39 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH 13/13] rcutorture: formal: prepare for ACCESS_ONCE() removal |
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On Tue, Oct 10, 2017 at 09:27:54AM -0700, Joe Perches wrote: > On Tue, 2017-10-10 at 07:52 -0700, Paul E. McKenney wrote: > > On Tue, Oct 10, 2017 at 01:50:39PM +0100, Mark Rutland wrote: > > > On Tue, Oct 10, 2017 at 05:47:12AM -0700, Paul E. McKenney wrote: > > > > On Tue, Oct 10, 2017 at 10:54:14AM +0100, Mark Rutland wrote: > > > > > On Mon, Oct 09, 2017 at 12:51:12PM -0700, Paul E. McKenney wrote: > > > > > > On Mon, Oct 09, 2017 at 07:28:50PM +0100, Mark Rutland wrote: > > > > > > > diff --git a/tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/barriers.h b/tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/barriers.h > > > > > > > index 6687acc..ee4e4f8 100644 > > > > > > > --- a/tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/barriers.h > > > > > > > +++ b/tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/barriers.h > > > > > > > @@ -34,8 +34,9 @@ > > > > > > > #define rs_smp_mb() do {} while (0) > > > > > > > #endif > > > > > > > > > > > > > > -#define ACCESS_ONCE(x) (*(volatile typeof(x) *) &(x)) > > > > > > > -#define READ_ONCE(x) ACCESS_ONCE(x) > > > > > > > -#define WRITE_ONCE(x, val) (ACCESS_ONCE(x) = (val)) > > > > > > > +#define __ACCESS_ONCE(x) (*(volatile typeof(x) *) &(x)) > > > > > > > +#define ACCESS_ONCE(x) __ACCESS_ONCE(x) > > > > > > > +#define READ_ONCE(x) __ACCESS_ONCE(x) > > > > > > > +#define WRITE_ONCE(x, val) (__ACCESS_ONCE(x) = (val)) > > > > > > > > > > > > How about something like the following? > > > > > > > > > > > > #define READ_ONCE(x) (*(volatile typeof(x) *) &(x)) > > > > > > #define WRITE_ONCE(x) ((*(volatile typeof(x) *) &(x)) = (val)) > > > > > > > > > > Sure; folded in and pushed out. :) > > > > > > > > Thank you! > > > > > > > > > I've assumed that the ACCESS_ONCE() definition needs to be kept until > > > > > that's ripped out treewide. Please shout if that's not the case! > > > > > > > > You have it right. This case is an exception because this code is > > > > used only by RCU, which has long since had ACCESS_ONCE() ripped out. > > > > > > Sorry; I meant that in this case, I leave this code as: > > > > > > #define ACCESS_ONCE(x) (*(volatile typeof(x) *) &(x)) > > > #define READ_ONCE(x) (*(volatile typeof(x) *) &(x)) > > > #define WRITE_ONCE(x) ((*(volatile typeof(x) *) &(x)) = (val)) > > > > > > ... if you mean that we can drop ACCESS_ONCE() in this case, then I can > > > rip that out. > > > > We can drop ACCESS_ONCE() in this case. > > Once ACCESS_ONCE is removed from the code in the tree > it can also be removed from checkpatch
Sure thing. We're expecting to rip that out with the ACCESS_ONCE definitions in a post-Coccinelle patch.
If you're happy to give a sign-off for the below, we can drop that into the post-coccienelle patch/series.
Thanks, Mark.
> --- > scripts/checkpatch.pl | 22 ---------------------- > 1 file changed, 22 deletions(-) > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl > index 2a8c6c3c1bdb..440262a87d26 100755 > --- a/scripts/checkpatch.pl > +++ b/scripts/checkpatch.pl > @@ -6224,28 +6224,6 @@ sub process { > } > } > > -# whine about ACCESS_ONCE > - if ($^V && $^V ge 5.10.0 && > - $line =~ /\bACCESS_ONCE\s*$balanced_parens\s*(=(?!=))?\s*($FuncArg)?/) { > - my $par = $1; > - my $eq = $2; > - my $fun = $3; > - $par =~ s/^\(\s*(.*)\s*\)$/$1/; > - if (defined($eq)) { > - if (WARN("PREFER_WRITE_ONCE", > - "Prefer WRITE_ONCE(<FOO>, <BAR>) over ACCESS_ONCE(<FOO>) = <BAR>\n" . $herecurr) && > - $fix) { > - $fixed[$fixlinenr] =~ s/\bACCESS_ONCE\s*\(\s*\Q$par\E\s*\)\s*$eq\s*\Q$fun\E/WRITE_ONCE($par, $fun)/; > - } > - } else { > - if (WARN("PREFER_READ_ONCE", > - "Prefer READ_ONCE(<FOO>) over ACCESS_ONCE(<FOO>)\n" . $herecurr) && > - $fix) { > - $fixed[$fixlinenr] =~ s/\bACCESS_ONCE\s*\(\s*\Q$par\E\s*\)/READ_ONCE($par)/; > - } > - } > - } > - > # check for mutex_trylock_recursive usage > if ($line =~ /mutex_trylock_recursive/) { > ERROR("LOCKING", >
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