[PATCH v3 2/7] vdpa/mlx5: fix dead loop when process interrupted

[Xueming Li <xuemingl@nvidia.com>]

In Ctrl+C handling, sometimes kick handling thread gets endless EGAIN
error and fall into dead lock.

Kick happens frequently in real system due to busy traffic or retry
mechanism. This patch simplifies kick firmware anyway and skip setting
hardware notifier due to potential device error, notifier could be set
in next successful kick request.

Fixes: 62c813706e41 ("vdpa/mlx5: map doorbell")
Cc: stable@dpdk.org

Signed-off-by: Xueming Li <xuemingl@nvidia.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 drivers/vdpa/mlx5/mlx5_vdpa_virtq.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c b/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c
index 2e517beda24..2696d54b412 100644
--- a/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c
+++ b/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c
@@ -23,11 +23,11 @@ mlx5_vdpa_virtq_kick_handler(void *cb_arg)
 	struct mlx5_vdpa_priv *priv = virtq->priv;
 	uint64_t buf;
 	int nbytes;
+	int retry;
 
 	if (rte_intr_fd_get(virtq->intr_handle) < 0)
 		return;
-
-	do {
+	for (retry = 0; retry < 3; ++retry) {
 		nbytes = read(rte_intr_fd_get(virtq->intr_handle), &buf,
 			      8);
 		if (nbytes < 0) {
@@ -39,7 +39,9 @@ mlx5_vdpa_virtq_kick_handler(void *cb_arg)
 				virtq->index, strerror(errno));
 		}
 		break;
-	} while (1);
+	}
+	if (nbytes < 0)
+		return;
 	rte_write32(virtq->index, priv->virtq_db_addr);
 	if (virtq->notifier_state == MLX5_VDPA_NOTIFIER_STATE_DISABLED) {
 		if (rte_vhost_host_notifier_ctrl(priv->vid, virtq->index, true))
-- 
2.35.1