checkpatch: forbid implied-barrier I/O functions.
Forbid read[bwl], write[bwl], in[bwl], and out[bwl], as they
contain a 'stealth barrier' which can harm performance.
Developers are expected to call appropriate __raw_* or *_relaxed
APIs and manage barriers explicitly.
Change-Id: Ie4da221c91a0505917199db9e2fdb704c3e47d44
Signed-off-by: Gregory Bean <gbean@codeaurora.org>
(cherry picked from commit 032fd4ba09e195d9913c08f460130da9905936ef)
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 0c8163e..4220555 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5089,6 +5089,26 @@
$herecurr);
}
+# read[bwl] & write[bwl] use too many barriers, use the _relaxed variants
+ if ($line =~ /\b((?:read|write)[bwl])\b/) {
+ ERROR("NON_RELAXED_IO",
+ "Use of $1 is deprecated: use $1_relaxed\n\t" .
+ "with appropriate memory barriers instead.\n" .
+ $herecurr);
+ }
+
+# likewise, in/out[bwl] should be __raw_read/write[bwl]...
+ if ($line =~ /\b((in|out)([bwl]))\b/) {
+ my ($all, $pref, $suf) = ($1, $2, $3);
+ $pref =~ s/in/read/;
+ $pref =~ s/out/write/;
+ ERROR("NON_RELAXED_IO",
+ "Use of $all is deprecated: use " .
+ "__raw_$pref$suf\n\t" .
+ "with appropriate memory barriers instead.\n" .
+ $herecurr);
+ }
+
# warn about #if 0
if ($line =~ /^.\s*\#\s*if\s+0\b/) {
WARN("IF_0",