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Message-Id: <20231102092712.30793-1-lirongqing@baidu.com> Date: Thu, 2 Nov 2023 17:27:12 +0800 From: Li RongQing <lirongqing@...du.com> To: linux-s390@...r.kernel.org, netdev@...r.kernel.org Subject: [PATCH] net/smc: avoid atomic_set and smp_wmb in the tx path when possible 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 <lirongqing@...du.com> --- 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
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