Messages in this thread Patch in this message | | | Date | Fri, 17 Nov 2023 17:48:46 +0100 | From | Oleg Nesterov <> | Subject | [PATCH] rxrpc_find_service_conn_rcu: fix the usage of read_seqbegin_or_lock() |
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rxrpc_find_service_conn_rcu() should make the "seq" counter odd on the second pass, otherwise read_seqbegin_or_lock() never takes the lock.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- net/rxrpc/conn_service.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/rxrpc/conn_service.c b/net/rxrpc/conn_service.c index 89ac05a711a4..39c908a3ca6e 100644 --- a/net/rxrpc/conn_service.c +++ b/net/rxrpc/conn_service.c @@ -25,7 +25,7 @@ struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *peer, struct rxrpc_conn_proto k; struct rxrpc_skb_priv *sp = rxrpc_skb(skb); struct rb_node *p; - unsigned int seq = 0; + unsigned int seq = 1; k.epoch = sp->hdr.epoch; k.cid = sp->hdr.cid & RXRPC_CIDMASK; @@ -35,6 +35,7 @@ struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *peer, * under just the RCU read lock, so we have to check for * changes. */ + seq++; /* 2 on the 1st/lockless path, otherwise odd */ read_seqbegin_or_lock(&peer->service_conn_lock, &seq); p = rcu_dereference_raw(peer->service_conns.rb_node); -- 2.25.1.362.g51ebf55
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