checkpatch.pl

# check for needless kfree() checks
		if ($prevline =~ /\bif\s*\(([^\)]*)\)/) {
			my $expr = $1;
			if ($line =~ /\bkfree\(\Q$expr\E\);/) {
				WARN("kfree(NULL) is safe this check is probabally not required\n" . $hereprev);
			}
		}

# warn about #ifdefs in C files
#		if ($line =~ /^.#\s*if(|n)def/ && ($realfile =~ /\.c$/)) {
#			print "#ifdef in C files should be avoided\n";
#			print "$herecurr";
#			$clean = 0;
#		}

# check for spinlock_t definitions without a comment.
		if ($line =~ /^.\s*(struct\s+mutex|spinlock_t)\s+\S+;/) {
			my $which = $1;
			if (!ctx_has_comment($first_line, $linenr)) {
				CHK("$1 definition without comment\n" . $herecurr);
			}
		}
# check for memory barriers without a comment.
		if ($line =~ /\b(mb|rmb|wmb|read_barrier_depends|smp_mb|smp_rmb|smp_wmb|smp_read_barrier_depends)\(/) {
			if (!ctx_has_comment($first_line, $linenr)) {
				CHK("memory barrier without comment\n" . $herecurr);
			}
		}
# check of hardware specific defines
		if ($line =~ m@^.#\s*if.*\b(__i386__|__powerpc64__|__sun__|__s390x__)\b@) {
			CHK("architecture specific defines should be avoided\n" .  $herecurr);
		}

# check the location of the inline attribute, that it is between
# storage class and type.
		if ($line =~ /$Type\s+(?:inline|__always_inline)\b/ ||
		    $line =~ /\b(?:inline|always_inline)\s+$Storage/) {
			ERROR("inline keyword should sit between storage class and type\n" . $herecurr);
		}

# check for new externs in .c files.
		if ($line =~ /^.\s*extern\s/ && ($realfile =~ /\.c$/)) {
			WARN("externs should be avoided in .c files\n" .  $herecurr);
		}

# checks for new __setup's
		if ($rawline =~ /\b__setup\("([^"]*)"/) {
			my $name = $1;

			if (!grep(/$name/, @setup_docs)) {
				CHK("__setup appears un-documented -- check Documentation/kernel-parameters.txt\n" . $herecurr);
			}
		}
	}

	if ($chk_patch && !$is_patch) {
		ERROR("Does not appear to be a unified-diff format patch\n");
	}
	if ($is_patch && $chk_signoff && $signoff == 0) {
		ERROR("Missing Signed-off-by: line(s)\n");
	}

	if ($clean == 0 && ($chk_patch || $is_patch)) {
		print report_dump();
	}
	if ($clean == 1 && $quiet == 0) {
		print "Your patch has no obvious style problems and is ready for submission.\n"
	}
	if ($clean == 0 && $quiet == 0) {
		print "Your patch has style problems, please review.  If any of these errors\n";
		print "are false positives report them to the maintainer, see\n";
		print "CHECKPATCH in MAINTAINERS.\n";
	}
	return $clean;
}