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authorJoe Perches <joe@perches.com>2014-08-06 16:10:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-06 18:01:27 -0700
commitebfdc40969f24fc0cdd1349835d36e8ebae05374 (patch)
treed43881f65568d89560feb76177bf9e959df97113
parent74e765319084bd2940a9612ada961f0f7385936c (diff)
checkpatch: attempt to find unnecessary 'out of memory' messages
Logging messages that show some type of "out of memory" error are generally unnecessary as there is a generic message and a stack dump done by the memory subsystem. These messages generally increase kernel size without much added value. Emit a warning on these types of messages. This test looks for any inserted message function, then looks at the previous line for an "if (!foo)" or "if (foo == NULL)" test and then looks at the preceding statement for an allocation function like "foo = kmalloc()" ie: this code matches: foo = kmalloc(); if (foo == NULL) { printk("Out of memory\n"); return -ENOMEM; } This test is very crude and incomplete. This test can miss quite a lot of of OOM messages that do not have this specific form. ie: this code does not match: foo = kmalloc(); if (!foo) { rtn = -ENOMEM; printk("Out of memory!\n"); goto out; } This test could also be a false positive when the logging message itself does not specify anything about memory, but I did not find any false positives in my limited testing. spatch could be a better solution but correctness seems non-trivial for that tool too. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rwxr-xr-xscripts/checkpatch.pl17
1 files changed, 17 insertions, 0 deletions
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 182be0f12407..ac1d6b0a6f09 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4014,6 +4014,23 @@ sub process {
}
}
+# check for unnecessary "Out of Memory" messages
+ if ($line =~ /^\+.*\b$logFunctions\s*\(/ &&
+ $prevline =~ /^[ \+]\s*if\s*\(\s*(\!\s*|NULL\s*==\s*)?($Lval)(\s*==\s*NULL\s*)?\s*\)/ &&
+ (defined $1 || defined $3) &&
+ $linenr > 3) {
+ my $testval = $2;
+ my $testline = $lines[$linenr - 3];
+
+ my ($s, $c) = ctx_statement_block($linenr - 3, $realcnt, 0);
+# print("line: <$line>\nprevline: <$prevline>\ns: <$s>\nc: <$c>\n\n\n");
+
+ if ($c =~ /(?:^|\n)[ \+]\s*(?:$Type\s*)?\Q$testval\E\s*=\s*(?:\([^\)]*\)\s*)?\s*(?:devm_)?(?:[kv][czm]alloc(?:_node|_array)?\b|kstrdup|(?:dev_)?alloc_skb)/) {
+ WARN("OOM_MESSAGE",
+ "Possible unnecessary 'out of memory' message\n" . $hereprev);
+ }
+ }
+
# check for bad placement of section $InitAttribute (e.g.: __initdata)
if ($line =~ /(\b$InitAttribute\b)/) {
my $attr = $1;

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