[dpdk-dev] [PATCH] net/mlx5: fix deadlock of link status alarm
Yongseok Koh
yskoh at mellanox.com
Tue Jan 9 10:09:20 CET 2018
If mlx5_dev_link_status_handler() is executed while canceling the alarm,
deadlock can happen because rte_eal_alarm_cancel() waits for all callbackes
to finish execution and both calls are protected by priv->lock.
Fixes: 198a3c339a8f ("mlx5: handle link status interrupts")
Cc: stable at dpdk.org
Signed-off-by: Yongseok Koh <yskoh at mellanox.com>
---
drivers/net/mlx5/mlx5.h | 16 ++++++++++++++++
drivers/net/mlx5/mlx5_ethdev.c | 13 +++++++++----
2 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index e6a69b823..1a4f444c7 100644
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -165,6 +165,22 @@ priv_lock(struct priv *priv)
}
/**
+ * Try to lock private structure to protect it from concurrent access in the
+ * control path.
+ *
+ * @param priv
+ * Pointer to private structure.
+ *
+ * @return
+ * 1 if the lock is successfully taken; 0 otherwise.
+ */
+static inline int
+priv_trylock(struct priv *priv)
+{
+ return rte_spinlock_trylock(&priv->lock);
+}
+
+/**
* Unlock private structure.
*
* @param priv
diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 282ef241e..9354dd17f 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -1185,8 +1185,12 @@ mlx5_dev_link_status_handler(void *arg)
struct priv *priv = dev->data->dev_private;
int ret;
- priv_lock(priv);
- assert(priv->pending_alarm == 1);
+ while (!priv_trylock(priv)) {
+ /* Alarm is being canceled. */
+ if (priv->pending_alarm == 0)
+ return;
+ rte_pause();
+ }
priv->pending_alarm = 0;
ret = priv_link_status_update(priv);
priv_unlock(priv);
@@ -1256,9 +1260,10 @@ priv_dev_interrupt_handler_uninstall(struct priv *priv, struct rte_eth_dev *dev)
if (priv->primary_socket)
rte_intr_callback_unregister(&priv->intr_handle_socket,
mlx5_dev_handler_socket, dev);
- if (priv->pending_alarm)
+ if (priv->pending_alarm) {
+ priv->pending_alarm = 0;
rte_eal_alarm_cancel(mlx5_dev_link_status_handler, dev);
- priv->pending_alarm = 0;
+ }
priv->intr_handle.fd = 0;
priv->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN;
priv->intr_handle_socket.fd = 0;
--
2.11.0
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