From: Michel Lespinasse <walken@google.com>
Date: Thu, 13 Sep 2012 00:58:46 +0000 (+1000)
Subject: rbtree: fix incorrect rbtree node insertion in fs/proc/proc_sysctl.c
X-Git-Tag: next-20120918~1^2~178
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b0c608a67e9383d7e7576b35ea122e23a62924ec;p=karo-tx-linux.git

rbtree: fix incorrect rbtree node insertion in fs/proc/proc_sysctl.c

The recently added code to use rbtrees in sysctl did not follow the proper
rbtree interface on insertion - it was calling rb_link_node() which
inserts a new node into the binary tree, but missed the call to
rb_insert_color() which properly balances the rbtree and establishes all
expected rbtree invariants.

I found out about this only because faulty commit also used
rb_init_node(), which I am removing within this patchset.  But I think
it's an easy mistake to make, and it makes me wonder if we should change
the rbtree API so that insertions would be done with a single rb_insert()
call (even if its implementation could still inline the rb_link_node()
part and call a private __rb_insert_color function to do the rebalancing).

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Santos <daniel.santos@pobox.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 080855bb6b74..a42243fa9cdb 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -142,6 +142,7 @@ static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
 	}
 
 	rb_link_node(node, parent, p);
+	rb_insert_color(node, &head->parent->root);
 	return 0;
 }