[PATCH V4] checkpatch: prefer eth_<foo>_addr over memset(,,ETH_ALEN)

[Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>]

Add 2 new checks on memset calls in the file checkpatch.pl as follows:

replace memset by eth_zero_addr if the second argument is
an address of zeros (0x00). eth_zero_addr is a wrapper function
for memset that takes an address array to set as zero. The size
address has to be ETH_ALEN.

replace memset by eth_broadcast_addr if the second argument is
the broadcast address (0xff). eth_broadcast_addr is a wrapper
function for memset that sets the passed array the broadcast
address. The size of the address has to be ETH_ALEN.

In addition, the regex assigned to the variable $stat has been
restricted to handle memset function calls of the form:
[<identifer> =]* memset(<arg1>, <arg2>, <arg3>)

Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Joe Perches <joe@perches.com>
Signed-off-by: Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>
[joe@perches.com: handled all regular expressions]
Portions-by: Joe Perches<joe@perches.com>
---
v2: adjusted all checks on memset calls to be in one body
v3: adjusted all regular expressions per Joe Perches suggestions. Added
a Signed-off-by tag for Joe since all the important regular expressions
are written by him.
v4: changed the patch's subject and modified the tags section.

 scripts/checkpatch.pl | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index d124359..cbe973e 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4890,10 +4890,11 @@ sub process {
 			}
 		}
 
-# Check for misused memsets
+# Check for misused memsets then check for memset(foo, 0x00|0xff, ETH_ALEN)
+# calls that could be eth_zero_addr(foo)|eth_broadcast_addr(foo)
 		if ($^V && $^V ge 5.10.0 &&
 		    defined $stat &&
-		    $stat =~ /^\+(?:.*?)\bmemset\s*\(\s*$FuncArg\s*,\s*$FuncArg\s*\,\s*$FuncArg\s*\)/s) {
+		    $stat =~ /^\+(?:\s*$Ident\s*=)?\s*memset\s*\(\s*$FuncArg\s*,\s*$FuncArg\s*\,\s*$FuncArg\s*\)/s) {
 
 			my $ms_addr = $2;
 			my $ms_val = $7;
@@ -4905,6 +4906,18 @@ sub process {
 			} elsif ($ms_size =~ /^(0x|)1$/i) {
 				WARN("MEMSET",
 				     "single byte memset is suspicious. Swapped 2nd/3rd argument?\n" . "$here\n$stat\n");
+			} elsif ($ms_val =~ /^(?:0x)?0+$/i &&
+				 $ms_size =~ /^ETH_ALEN$/ &&
+				 WARN("PREFER_ETH_ADDR",
+				     "Prefer eth_zero_addr() over memset() if the second address is 0\n" . $herecurr) &&
+				 $fix) {
+				$fixed[$fixlinenr] =~ s/\bmemset\s*\(\s*\Q$ms_addr\E\s*,\s*\Q$ms_val\E\s*,\s*ETH_ALEN\s*\)/eth_zero_addr($ms_addr)/;
+			} elsif ($ms_val =~ /^(?:0xff|255)$/i &&
+				 $ms_size =~ /^ETH_ALEN$/ &&
+				 WARN("PREFER_ETH_ADDR",
+				      "Prefer eth_broadcast_addr() over memset() if the second address is 0xff\n" . $herecurr) &&
+				 $fix) {
+				$fixed[$fixlinenr] =~ s/\bmemset\s*\(\s*\Q$ms_addr\E\s*,\s*\Q$ms_val\E\s*,\s*ETH_ALEN\s*\)/eth_broadcast_addr($ms_addr)/;
 			}
 		}
 
-- 
1.9.3


-- 
Kind Regards,
Aya Saif El-yazal Mahfouz