Re: [Qemu-devel] [PATCH] checkpatch: warn when using volatile with a comment

[Paolo Bonzini <pbonzini@redhat.com>]

On 15/12/2017 19:18, Marc-André Lureau wrote:
> Instead of an error, lower to a warning message, assuming the comment
> gives some justification.
> 
> Discussed in:
> '[Qemu-devel] [PATCH] dump-guest-memory.py: fix "You can't do that without a process to debug"'
> 
> Suggested-by: Fam Zheng <famz@redhat.com>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

We can drop the error at all if there is a comment.  Also, "volatile sig_atomic_t" is probably self-explanatory and usually correct.  So what about this:

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index f5a523af10..3dc27d9656 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2475,13 +2475,11 @@ sub process {
 
 # no volatiles please
 		my $asm_volatile = qr{\b(__asm__|asm)\s+(__volatile__|volatile)\b};
-		if ($line =~ /\bvolatile\b/ && $line !~ /$asm_volatile/) {
-			my $msg = "Use of volatile is usually wrong: see Documentation/volatile-considered-harmful.txt\n" . $herecurr;
-			if (ctx_has_comment($first_line, $linenr)) {
-				WARN($msg);
-			} else {
-				ERROR($msg);
-			}
+		if ($line =~ /\bvolatile\b/ && $line !~ /$asm_volatile/ &&
+                    $line !~ /sig_atomic_t/ &&
+                    !ctx_has_comment($first_line, $linenr)) {
+			my $msg = "Use of volatile is usually wrong, please add a comment\n" . $herecurr;
+                        ERROR($msg);
 		}
 
 # warn about #if 0