net/smc: do not wait under send_lock

[ Upstream commit 33f3fcc290671590821ff3c0c9396db1ec9b7d4c ]

smc_cdc_get_free_slot() might wait for free transfer buffers when using
SMC-R. This wait should not be done under the send_lock, which is a
spin_lock. This fixes a cpu loop in parallel threads waiting for the
send_lock.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
index 0ecbbdc..62885a2 100644 (file)
--- a/net/smc/smc_tx.c
+++ b/net/smc/smc_tx.c
@@ -486,25 +486,23 @@ static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
        struct smc_wr_buf *wr_buf;
        int rc;
 
-       spin_lock_bh(&conn->send_lock);
        rc = smc_cdc_get_free_slot(conn, &wr_buf, &pend);
        if (rc < 0) {
                if (rc == -EBUSY) {
                        struct smc_sock *smc =
                                container_of(conn, struct smc_sock, conn);
 
-                       if (smc->sk.sk_err == ECONNABORTED) {
-                               rc = sock_error(&smc->sk);
-                               goto out_unlock;
-                       }
+                       if (smc->sk.sk_err == ECONNABORTED)
+                               return sock_error(&smc->sk);
                        rc = 0;
                        if (conn->alert_token_local) /* connection healthy */
                                mod_delayed_work(system_wq, &conn->tx_work,
                                                 SMC_TX_WORK_DELAY);
                }
-               goto out_unlock;
+               return rc;
        }
 
+       spin_lock_bh(&conn->send_lock);
        if (!conn->local_tx_ctrl.prod_flags.urg_data_present) {
                rc = smc_tx_rdma_writes(conn);
                if (rc) {