Commit 99ca38c2 authored Oct 15, 2020 by Joe Perches Committed by Linus Torvalds Oct 16, 2020

checkpatch: warn on self-assignments



The uninitialized_var() macro was removed recently via commit 63a0895d
("compiler: Remove uninitialized_var() macro") as it's not a particularly
useful warning and its use can "paper over real bugs".

Add a checkpatch test to warn on self-assignments as a means to avoid
compiler warnings and as a back-door mechanism to reproduce the old
uninitialized_var macro behavior.

[akpm@linux-foundation.org: coding style fixes]

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Denis Efremov <efremov@linux.com>
Cc: Julia Lawall <julia.lawall@inria.fr>
Link: https://lkml.kernel.org/r/afc2cffdd315d3e4394af149278df9e8af7f49f4.camel@perches.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent c12093a1

scripts/checkpatch.pl

+11 −0

Original line number	Diff line number	Diff line
		@@ -3899,6 +3899,17 @@ sub process {
		#ignore lines not being added
		next if ($line =~ /^[^\+]/);

		# check for self assignments used to avoid compiler warnings
		# e.g.: int foo = foo, *bar = NULL;
		# struct foo bar = *(&(bar));
		if ($line =~ /^\+\s(?:$Declare)?([A-Za-z_][A-Za-z\d_])\s*=/) {
		my $var = $1;
		if ($line =~ /^\+\s(?:$Declare)?$var\s=\s(?:$var\|\\s$?\s&\s\(?\s$var\s$?\s\)?)\s*[;,]/) {
		WARN("SELF_ASSIGNMENT",
		"Do not use self-assignments to avoid compiler warnings\n" . $herecurr);
		}
		}

		# check for dereferences that span multiple lines
		if ($prevline =~ /^\+.$Lval\s(?:\.\|->)\s*$/ &&
		$line =~ /^\+\s(?!\#\s(?!define\s+\|if))\s*$Lval/) {

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