checkpatch: whine about ACCESS_ONCE

Add a test for use of ACCESS_ONCE that could be written using READ_ONCE or WRITE_ONCE. --fix it too if desired. The WRITE_ONCE fixes are less correct than the coccinelle script below as checkpatch cannot have a completely correct "expression" mechanism because checkpatch works on patches and not complete files. $ cat access_once.cocci @@ expression e1; expression e2; @@ - ACCESS_ONCE(e1) = e2 + WRITE_ONCE(e1, e2) @@ expression e1; @@ - ACCESS_ONCE(e1) + READ_ONCE(e1) Signed-off-by: Joe Perches <[email protected]> Cc: Julia Lawall <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
kyagi · May 21, 2016 · 481aea5 · 481aea5
1 parent a91e899
commit 481aea5
Showing 1 changed file with 22 additions and 0 deletions.
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
@@ -5850,6 +5850,28 @@ 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($par)/;
+				}
+			}
+		}
+
 # check for lockdep_set_novalidate_class
 		if ($line =~ /^.\s*lockdep_set_novalidate_class\s*\(/ ||
 		    $line =~ /__lockdep_no_validate__\s*\)/ ) {