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

Greg KH
2007-03-19T21:43:05Z

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

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From: Robert Olsson <robert.olsson@its.uu.se>

[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@its.uu.se>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
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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