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Commit 592d29eb authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Greg Kroah-Hartman
Browse files

rxrpc_find_service_conn_rcu: fix the usage of read_seqbegin_or_lock() 



[ Upstream commit bad1a11c0f061aa073bab785389fe04f19ba02e1 ]

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: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/20231117164846.GA10410@redhat.com/


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent f4a0b576

net/rxrpc/conn_service.c

+2 −1
Original line number Diff line number Diff line
@@ -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);