checkpatch: add some <foo>_destroy functions to NEEDLESS_IF tests

Sergey Senozhatsky has modified several destroy functions that can
now be called with NULL values.

 - kmem_cache_destroy()
 - mempool_destroy()
 - dma_pool_destroy()

Update checkpatch to warn when those functions are preceded by an if.

Update checkpatch to --fix all the calls too only when the code style
form is using leading tabs.

from:
	if (foo)
		<func>(foo);
to:
	<func>(foo);

Signed-off-by: Joe Perches <joe@perches.com>
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 25314f37e79e8f4b320c1f1a44d0f658b862a8e4..780c91d82aa9a649b00df444515245bc22841fce 100755 (executable)
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4836,10 +4836,34 @@ sub process {
 
 # check for needless "if (<foo>) fn(<foo>)" uses
                if ($prevline =~ /\bif\s*\(\s*($Lval)\s*\)/) {
-                       my $expr = '\s*\(\s*' . quotemeta($1) . '\s*\)\s*;';
-                       if ($line =~ /\b(kfree|usb_free_urb|debugfs_remove(?:_recursive)?)$expr/) {
-                               WARN('NEEDLESS_IF',
-                                    "$1(NULL) is safe and this check is probably not required\n" . $hereprev);
+                       my $tested = quotemeta($1);
+                       my $expr = '\s*\(\s*' . $tested . '\s*\)\s*;';
+                       if ($line =~ /\b(kfree|usb_free_urb|debugfs_remove(?:_recursive)?|(?:kmem_cache|mempool|dma_pool)_destroy)$expr/) {
+                               my $func = $1;
+                               if (WARN('NEEDLESS_IF',
+                                        "$func(NULL) is safe and this check is probably not required\n" . $hereprev) &&
+                                   $fix) {
+                                       my $do_fix = 1;
+                                       my $leading_tabs = "";
+                                       my $new_leading_tabs = "";
+                                       if ($lines[$linenr - 2] =~ /^\+(\t*)if\s*\(\s*$tested\s*\)\s*$/) {
+                                               $leading_tabs = $1;
+                                       } else {
+                                               $do_fix = 0;
+                                       }
+                                       if ($lines[$linenr - 1] =~ /^\+(\t+)$func\s*\(\s*$tested\s*\)\s*;\s*$/) {
+                                               $new_leading_tabs = $1;
+                                               if (length($leading_tabs) + 1 ne length($new_leading_tabs)) {
+                                                       $do_fix = 0;
+                                               }
+                                       } else {
+                                               $do_fix = 0;
+                                       }
+                                       if ($do_fix) {
+                                               fix_delete_line($fixlinenr - 1, $prevrawline);
+                                               $fixed[$fixlinenr] =~ s/^\+$new_leading_tabs/\+$leading_tabs/;
+                                       }
+                               }
                        }
                }