| From 41547a788ddf484519e9c27945d41e7a391e3fa8 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 31 Jan 2022 02:02:55 +0800 |
| Subject: net/smc: Send directly when TCP_CORK is cleared |
| |
| From: Tony Lu <tonylu@linux.alibaba.com> |
| |
| [ Upstream commit ea785a1a573b390a150010b3c5b81e1ccd8c98a8 ] |
| |
| According to the man page of TCP_CORK [1], if set, don't send out |
| partial frames. All queued partial frames are sent when option is |
| cleared again. |
| |
| When applications call setsockopt to disable TCP_CORK, this call is |
| protected by lock_sock(), and tries to mod_delayed_work() to 0, in order |
| to send pending data right now. However, the delayed work smc_tx_work is |
| also protected by lock_sock(). There introduces lock contention for |
| sending data. |
| |
| To fix it, send pending data directly which acts like TCP, without |
| lock_sock() protected in the context of setsockopt (already lock_sock()ed), |
| and cancel unnecessary dealyed work, which is protected by lock. |
| |
| [1] https://linux.die.net/man/7/tcp |
| |
| Signed-off-by: Tony Lu <tonylu@linux.alibaba.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| net/smc/af_smc.c | 4 ++-- |
| net/smc/smc_tx.c | 25 +++++++++++++++---------- |
| net/smc/smc_tx.h | 1 + |
| 3 files changed, 18 insertions(+), 12 deletions(-) |
| |
| diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c |
| index a0fb596459a3..0ec721b8059a 100644 |
| --- a/net/smc/af_smc.c |
| +++ b/net/smc/af_smc.c |
| @@ -2632,8 +2632,8 @@ static int smc_setsockopt(struct socket *sock, int level, int optname, |
| sk->sk_state != SMC_CLOSED) { |
| if (!val) { |
| SMC_STAT_INC(smc, cork_cnt); |
| - mod_delayed_work(smc->conn.lgr->tx_wq, |
| - &smc->conn.tx_work, 0); |
| + smc_tx_pending(&smc->conn); |
| + cancel_delayed_work(&smc->conn.tx_work); |
| } |
| } |
| break; |
| diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c |
| index be241d53020f..7b0b6e24582f 100644 |
| --- a/net/smc/smc_tx.c |
| +++ b/net/smc/smc_tx.c |
| @@ -597,27 +597,32 @@ int smc_tx_sndbuf_nonempty(struct smc_connection *conn) |
| return rc; |
| } |
| |
| -/* Wakeup sndbuf consumers from process context |
| - * since there is more data to transmit |
| - */ |
| -void smc_tx_work(struct work_struct *work) |
| +void smc_tx_pending(struct smc_connection *conn) |
| { |
| - struct smc_connection *conn = container_of(to_delayed_work(work), |
| - struct smc_connection, |
| - tx_work); |
| struct smc_sock *smc = container_of(conn, struct smc_sock, conn); |
| int rc; |
| |
| - lock_sock(&smc->sk); |
| if (smc->sk.sk_err) |
| - goto out; |
| + return; |
| |
| rc = smc_tx_sndbuf_nonempty(conn); |
| if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked && |
| !atomic_read(&conn->bytes_to_rcv)) |
| conn->local_rx_ctrl.prod_flags.write_blocked = 0; |
| +} |
| + |
| +/* Wakeup sndbuf consumers from process context |
| + * since there is more data to transmit |
| + */ |
| +void smc_tx_work(struct work_struct *work) |
| +{ |
| + struct smc_connection *conn = container_of(to_delayed_work(work), |
| + struct smc_connection, |
| + tx_work); |
| + struct smc_sock *smc = container_of(conn, struct smc_sock, conn); |
| |
| -out: |
| + lock_sock(&smc->sk); |
| + smc_tx_pending(conn); |
| release_sock(&smc->sk); |
| } |
| |
| diff --git a/net/smc/smc_tx.h b/net/smc/smc_tx.h |
| index 07e6ad76224a..a59f370b8b43 100644 |
| --- a/net/smc/smc_tx.h |
| +++ b/net/smc/smc_tx.h |
| @@ -27,6 +27,7 @@ static inline int smc_tx_prepared_sends(struct smc_connection *conn) |
| return smc_curs_diff(conn->sndbuf_desc->len, &sent, &prep); |
| } |
| |
| +void smc_tx_pending(struct smc_connection *conn); |
| void smc_tx_work(struct work_struct *work); |
| void smc_tx_init(struct smc_sock *smc); |
| int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len); |
| -- |
| 2.35.1 |
| |