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inetpeer: fix RCU lookup() 

Excess of seafood or something happened while I cooked the commit
adding RB tree to inetpeer.

Of course, RCU rules need to be respected or bad things can happen.

In this particular loop, we need to read *pp once per iteration, not
twice.

Fixes: b145425f26 ("inetpeer: remove AVL implementation in favor of RB tree")
Reported-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-09-01 14:03:32 -07:00 committed by David S. Miller
parent bbd9644e84
commit 4cc5b44b29
1 changed files with 6 additions and 3 deletions
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9
net/ipv4/inetpeer.c
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@ -102,15 +102,18 @@ static struct inet_peer *lookup(const struct inetpeer_addr *daddr,
struct rb_node **parent_p, struct rb_node **parent_p,
struct rb_node ***pp_p) struct rb_node ***pp_p)
{ {
struct rb_node **pp, *parent; struct rb_node **pp, *parent, *next;
struct inet_peer *p; struct inet_peer *p;
pp = &base->rb_root.rb_node; pp = &base->rb_root.rb_node;
parent = NULL; parent = NULL;
while (*pp) { while (1) {
int cmp; int cmp;
parent = rcu_dereference_raw(*pp); next = rcu_dereference_raw(*pp);
if (!next)
break;
parent = next;
p = rb_entry(parent, struct inet_peer, rb_node); p = rb_entry(parent, struct inet_peer, rb_node);
cmp = inetpeer_addr_cmp(daddr, &p->daddr); cmp = inetpeer_addr_cmp(daddr, &p->daddr);
if (cmp == 0) { if (cmp == 0) {