[PATCH v2] checkpatch: Check for invalid return codes

[Prakruthi Deepak Heragu]

Negative integer return codes should prefer to use #define -<ERRNO>
values instead of negative numbers. This patch checks if there are any
negative numbers returned. Also, display context so that the user knows
where the return value is incorrect.

http://lkml.org/lkml/2010/7/23/318
  There's lots of "return -1;" statements in this patch - it's obscene
  that this is used to indicate "some error occurred" in kernel space
  rather than a real errno value - even when an existing function
  (eg, request_irq) gave you an error code already.

Signed-off-by: Prakruthi Deepak Heragu <pheragu@xxxxxxxxxxxxxx>
---
Changes in v2:
- Edit the descritpion to 'avoid returning any negative integers' rather 
  than saying 'returning anything but 0 is incorrect'
- Use APPROPRIATE_ERRNO instead of NO_ERROR_CODE as type of the message

Changes in v1:
- Use CHK instead of ERROR
- Rephrase the warning message
- Provide the file name and line number where return value is incorrect
 scripts/checkpatch.pl | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index a9c0550..0f9c717 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6197,6 +6197,12 @@ sub process {
 			     "switch default: should use break\n" . $herectx);
 		}
 
+# check for return codes on error paths
+		if ($line =~ /\breturn\s+-\d+/) {
+			CHK("APPROPRIATE_ERRNO",
+			      "invalid return value, please return -<APPROPRIATE_ERRNO>\n" . $herecurr);
+		}
+
 # check for gcc specific __FUNCTION__
 		if ($line =~ /\b__FUNCTION__\b/) {
 			if (WARN("USE_FUNC",
-- 
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