[PATCH] net/smc: avoid atomic_set and smp_wmb in the tx path when possible
From: Li RongQing <hidden>
Date: 2023-11-02 09:27:17
Also in:
linux-s390
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, Mahanta Jambigi, Linus Torvalds
these is less opportunity that conn->tx_pushing is not 1, since tx_pushing is just checked with 1, so move the setting tx_pushing to 1 after atomic_dec_and_test() return false, to avoid atomic_set and smp_wmb in tx path when possible Signed-off-by: Li RongQing <redacted> --- net/smc/smc_tx.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
index 3b0ff3b..72dbdee 100644
--- a/net/smc/smc_tx.c
+++ b/net/smc/smc_tx.c@@ -667,8 +667,6 @@ int smc_tx_sndbuf_nonempty(struct smc_connection *conn) return 0; again: - atomic_set(&conn->tx_pushing, 1); - smp_wmb(); /* Make sure tx_pushing is 1 before real send */ rc = __smc_tx_sndbuf_nonempty(conn); /* We need to check whether someone else have added some data into
@@ -677,8 +675,11 @@ int smc_tx_sndbuf_nonempty(struct smc_connection *conn) * If so, we need to push again to prevent those data hang in the send * queue. */ - if (unlikely(!atomic_dec_and_test(&conn->tx_pushing))) + if (unlikely(!atomic_dec_and_test(&conn->tx_pushing))) { + atomic_set(&conn->tx_pushing, 1); + smp_wmb(); /* Make sure tx_pushing is 1 before real send */ goto again; + } return rc; }
--
2.9.4