checkpatch: returning errno typically should be negative

Add a (strict mode only) test to check for non-negative returns of what
appear to be errno values as the majority case these should indeed be
negative.

Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 3cec2990d51e..bcdb54bd61a0 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2204,6 +2204,13 @@ sub process {
                                 ERROR("space required before the open parenthesis '('\n" . $herecurr);
                         }
                 }
+# Return of what appears to be an errno should normally be -'ve
+                if ($line =~ /^.\s*return\s*(E[A-Z]*)\s*;/) {
+                        my $name = $1;
+                        if ($name ne 'EOF' && $name ne 'ERROR') {
+                                WARN("return of an errno should typically be -ve (return -$1)\n" . $herecurr);
+                        }
+                }
 
 # Need a space before open parenthesis after if, while etc
                 if ($line=~/\b(if|while|for|switch)\(/) {