checkpatch: check usleep_range() arguments

usleep_range() shouldn't use the same args for min and max.

Report it when it happens and when both args are decimal and min > max.
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Yuval Mintz <yuvalmin@broadcom.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -3313,6 +3313,22 @@ sub process {
 			}
 		}
 
+# check usleep_range arguments
+		if ($^V && $^V ge 5.10.0 &&
+		    defined $stat &&
+		    $stat =~ /^\+(?:.*?)\busleep_range\s*\(\s*($FuncArg)\s*,\s*($FuncArg)\s*\)/) {
+			my $min = $1;
+			my $max = $7;
+			if ($min eq $max) {
+				WARN("USLEEP_RANGE",
+				     "usleep_range should not use min == max args; see Documentation/timers/timers-howto.txt\n" . "$here\n$stat\n");
+			} elsif ($min =~ /^\d+$/ && $max =~ /^\d+$/ &&
+				 $min > $max) {
+				WARN("USLEEP_RANGE",
+				     "usleep_range args reversed, use min then max; see Documentation/timers/timers-howto.txt\n" . "$here\n$stat\n");
+			}
+		}
+
 # check for new externs in .c files.
 		if ($realfile =~ /\.c$/ && defined $stat &&
 		    $stat =~ /^.\s*(?:extern\s+)?$Type\s+($Ident)(\s*)\(/s)