[PATCH AUTOSEL 4.19 594/671] net/smc: receive pending data after RCV_SHUTDOWN
From: Sasha Levin <sashal@kernel.org>
Date: 2020-01-16 18:36:57
Also in:
linux-s390, lkml, netdev
Subsystem:
networking [general], shared memory communications (smc) sockets, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, D. Wythe, Dust Li, Sidraya Jayagond, Wenjia Zhang, Linus Torvalds
From: Karsten Graul <redacted>
[ Upstream commit 107529e31a87acd475ff6a0f82745821b8f70fec ]
smc_rx_recvmsg() first checks if data is available, and then if
RCV_SHUTDOWN is set. There is a race when smc_cdc_msg_recv_action() runs
in between these 2 checks, receives data and sets RCV_SHUTDOWN.
In that case smc_rx_recvmsg() would return from receive without to
process the available data.
Fix that with a final check for data available if RCV_SHUTDOWN is set.
Move the check for data into a function and call it twice.
And use the existing helper smc_rx_data_available().
Fixes: 952310ccf2d8 ("smc: receive data from RMBE")
Reviewed-by: Ursula Braun <redacted>
Signed-off-by: Karsten Graul <redacted>
Signed-off-by: Jakub Kicinski <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/smc/smc_rx.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/net/smc/smc_rx.c b/net/smc/smc_rx.c
index 1ee5fdbf8284..36340912df48 100644
--- a/net/smc/smc_rx.c
+++ b/net/smc/smc_rx.c@@ -262,6 +262,18 @@ static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len, return -EAGAIN; } +static bool smc_rx_recvmsg_data_available(struct smc_sock *smc) +{ + struct smc_connection *conn = &smc->conn; + + if (smc_rx_data_available(conn)) + return true; + else if (conn->urg_state == SMC_URG_VALID) + /* we received a single urgent Byte - skip */ + smc_rx_update_cons(smc, 0); + return false; +} + /* smc_rx_recvmsg - receive data from RMBE * @msg: copy data to receive buffer * @pipe: copy data to pipe if set - indicates splice() call
@@ -303,15 +315,18 @@ int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, if (read_done >= target || (pipe && read_done)) break; - if (atomic_read(&conn->bytes_to_rcv)) + if (smc_rx_recvmsg_data_available(smc)) goto copy; - else if (conn->urg_state == SMC_URG_VALID) - /* we received a single urgent Byte - skip */ - smc_rx_update_cons(smc, 0); if (sk->sk_shutdown & RCV_SHUTDOWN || - conn->local_tx_ctrl.conn_state_flags.peer_conn_abort) + conn->local_tx_ctrl.conn_state_flags.peer_conn_abort) { + /* smc_cdc_msg_recv_action() could have run after + * above smc_rx_recvmsg_data_available() + */ + if (smc_rx_recvmsg_data_available(smc)) + goto copy; break; + } if (read_done) { if (sk->sk_err ||
--
2.20.1