From mboxrd@z Thu Jan  1 00:00:00 1970
From: elfring@users.sourceforge.net (SF Markus Elfring)
Date: Tue, 25 Feb 2014 18:28:36 +0100
Subject: [Cocci] Remove unnecessary null pointer checks?
In-Reply-To: <alpine.DEB.2.10.1402251014170.2080@hadrien>
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 <alpine.DEB.2.02.1402240658210.2090@localhost6.localdomain6>
 <530B5FB6.6010207@users.sourceforge.net>
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Message-ID: <530CD2C4.4050903@users.sourceforge.net>
To: cocci@systeme.lip6.fr
List-Id: cocci@systeme.lip6.fr

> I'm not sure to understand your goal.

I get an interesting result for example if I try the following source code
search pattern out. Do you find it useful?

@Delete_unnecessary_checks@
expression x;
identifier release =~ "^(?x)
(?:
   (?:kz?|slob_)free
|
   (?:
      abc
   |  xyz
   )
)$";
@@
-if (x)
    release(...,x,...);

elfring at Sonne:~/Projekte/Coccinelle/janitor> spatch --sp-file
delete_unnecessary_checks1.cocci /usr/src/linux-stable/fs/btrfs/inode.c
init_defs_builtins: /usr/local/share/coccinelle/standard.h
HANDLING: /usr/src/linux-stable/fs/btrfs/inode.c
diff =
--- /usr/src/linux-stable/fs/btrfs/inode.c
+++ /tmp/cocci-output-3740-5d95d8-inode.c
@@ -5137,8 +5137,7 @@ static int btrfs_dentry_delete(const str

 static void btrfs_dentry_release(struct dentry *dentry)
 {
-       if (dentry->d_fsdata)
-               kfree(dentry->d_fsdata);
+       kfree(dentry->d_fsdata);
 }


> If you remove the NULL test, you could drastically change the behavior
> of the program.

But it seems that I stumble on a software debug challenge after I replaced the
dummy alternation in the regular expression above by the real list of 5142
function names which were found by the other discussed pattern.

elfring at Sonne:~/Projekte/Coccinelle/janitor> spatch --sp-file
delete_unnecessary_checks2.cocci /usr/src/linux-stable/fs/btrfs/inode.c
init_defs_builtins: /usr/local/share/coccinelle/standard.h
Fatal error: exception Pcre.Error(_)

Regards,
Markus