net/smc: improved fix wait on already cleared link

Commit 8f3d65c16679 ("net/smc: fix wait on already cleared link")
introduced link refcounting to avoid waits on already cleared links.
This patch extents and improves the refcounting to cover all
remaining possible cases for this kind of error situation.

Fixes: 15e1b99aadfb ("net/smc: no WR buffer wait for terminating link group")
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 17 deletions

diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
index c79361dfcdfb..738a4a99c827 100644
--- a/net/smc/smc_tx.c
+++ b/net/smc/smc_tx.c
@@ -496,7 +496,7 @@ static int smc_tx_rdma_writes(struct smc_connection *conn,
 /* Wakeup sndbuf consumers from any context (IRQ or process)
  * since there is more data to transmit; usable snd_wnd as max transmit
  */
-static int _smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
+static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
 {
 	struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags;
 	struct smc_link *link = conn->lnk;
@@ -505,8 +505,11 @@ static int _smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
 	struct smc_wr_buf *wr_buf;
 	int rc;
 
+	if (!link || !smc_wr_tx_link_hold(link))
+		return -ENOLINK;
 	rc = smc_cdc_get_free_slot(conn, link, &wr_buf, &wr_rdma_buf, &pend);
 	if (rc < 0) {
+		smc_wr_tx_link_put(link);
 		if (rc == -EBUSY) {
 			struct smc_sock *smc =
 				container_of(conn, struct smc_sock, conn);
@@ -547,22 +550,7 @@ static int _smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
 
 out_unlock:
 	spin_unlock_bh(&conn->send_lock);
-	return rc;
-}
-
-static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
-{
-	struct smc_link *link = conn->lnk;
-	int rc = -ENOLINK;
-
-	if (!link)
-		return rc;
-
-	atomic_inc(&link->wr_tx_refcnt);
-	if (smc_link_usable(link))
-		rc = _smcr_tx_sndbuf_nonempty(conn);
-	if (atomic_dec_and_test(&link->wr_tx_refcnt))
-		wake_up_all(&link->wr_tx_wait);
+	smc_wr_tx_link_put(link);
 	return rc;
 }