linux-kernel - [PATCH driver-core-next] kernfs: remove unnecessary NULL check in __kernfs

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Message-ID: <20140111232323.GA7584@mtj.dyndns.org>
Date:	Sat, 11 Jan 2014 18:23:23 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH driver-core-next] kernfs: remove unnecessary NULL check in
 __kernfs_remove()

895a068a524e ("kernfs: make kernfs_get_active() block if the node is
deactivated but not removed") added "struct kernfs_root *root =
kernfs_root(kn);" at the head of the function; however, the parameter
@kn is checked for later implying that the function may be called with
NULL.  This means that we may end up invoking kernfs_root() with NULL
which will oops.  None of the existing users invokes removal with NULL
@kn, so this bug doesn't actually trigger.

We can relocate kernfs_root() invocation after NULL check; however,
allowing NULL param tends to cause more confusion than actually
helping anything.  As there's no existing user, let's remove the
spurious NULL check.

This bug was detected by smatch.

Signed-off-by: Tejun Heo <tj@...nel.org>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 fs/kernfs/dir.c |    3 ---
 1 file changed, 3 deletions(-)

--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -920,9 +920,6 @@ static void __kernfs_remove(struct kernf

 	lockdep_assert_held(&kernfs_mutex);

-	if (!kn)
-		return;
-
 	pr_debug("kernfs %s: removing\n", kn->name);

 	__kernfs_deactivate(kn);

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