[patch 19/31] : Fix GFP_KERNEL with preemption disabled in fib_trie

[Greg KH]

-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Robert Olsson <robert.olsson@xxxxxxxxx>

[IPV4]: Do not disable preemption in trie_leaf_remove().

Hello, Just discussed this Patrick...

We have two users of trie_leaf_remove, fn_trie_flush and fn_trie_delete
both are holding RTNL. So there shouldn't be need for this preempt stuff.
This is assumed to a leftover from an older RCU-take.

> Mhh .. I think I just remembered something - me incorrectly suggesting
> to add it there while we were talking about this at OLS :) IIRC the
> idea was to make sure tnode_free (which at that time didn't use
> call_rcu) wouldn't free memory while still in use in a rcu read-side
> critical section. It should have been synchronize_rcu of course,
> but with tnode_free using call_rcu it seems to be completely
> unnecessary. So I guess we can simply remove it.

Signed-off-by: Robert Olsson <robert.olsson@xxxxxxxxx>
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 net/ipv4/fib_trie.c |    2 --
 1 file changed, 2 deletions(-)

--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1528,7 +1528,6 @@ static int trie_leaf_remove(struct trie 
 	t->revision++;
 	t->size--;
 
-	preempt_disable();
 	tp = NODE_PARENT(n);
 	tnode_free((struct tnode *) n);
 
@@ -1538,7 +1537,6 @@ static int trie_leaf_remove(struct trie 
 		rcu_assign_pointer(t->trie, trie_rebalance(t, tp));
 	} else
 		rcu_assign_pointer(t->trie, NULL);
-	preempt_enable();
 
 	return 1;
 }

-- 
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