[dpdk-dev] [RFC v3] ethdev: claim device reset as async

[Qi Zhang <qi.z.zhang@intel.com>]

Device reset should be implemented in an async way since it is
possible to be invoked in interrupt thread and sometimes to reset a
device need to wait for some dependency, for example, a VF expects for
PF ready or a NIC function as part of a SOC wait for the whole system
reset complete, and all these time-consuming tasks will block the
interrupt thread.
The patch rename rte_eth_dev_reset to rte_eth_dev_reset_async and
rework the implementation. It will spawn a new thread which will call
ops->dev_reset, and when finished it will raise the event
RTE_ETH_EVENT_RESET_COMPLETE. The application should always wait for
this event before it continues to configure and restart the device.

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
---
 app/test-pmd/testpmd.c         | 50 +++++++++++++++++++++++++++++++++++++++++-
 lib/librte_ethdev/rte_ethdev.c | 50 +++++++++++++++++++++++++++++++++++++++---
 lib/librte_ethdev/rte_ethdev.h | 48 ++++++++++++++++++++++++----------------
 3 files changed, 125 insertions(+), 23 deletions(-)

diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
index ee48db2a3..ce3d9931b 100644
--- a/app/test-pmd/testpmd.c
+++ b/app/test-pmd/testpmd.c
@@ -1918,6 +1918,54 @@ close_port(portid_t pid)
 	printf("Done\n");
 }
 
+static int reset_ret;
+static int reset_done;
+
+static int
+on_reset_complete(__rte_unused uint16_t port_id,
+		__rte_unused enum rte_eth_event_type event,
+		__rte_unused void *cb_arg,
+		void *ret_param)
+{
+	RTE_ASSERT(event == RTE_ETH_EVENT_RESET_COMPLETE);
+
+	reset_ret = *(int *)ret_param;
+	reset_done = 1;
+	return 0;
+}
+
+static int
+do_dev_reset_sync(portid_t pid)
+{
+	int ret;
+
+	ret = rte_eth_dev_callback_register(pid,
+			RTE_ETH_EVENT_RESET_COMPLETE,
+			on_reset_complete, NULL);
+
+	if (ret) {
+		printf("Fail to reigster callback function\n");
+		return ret;
+	}
+
+	reset_done = 0;
+	ret = rte_eth_dev_reset_async(pid);
+	if (ret)
+		goto finish;
+
+	while (!reset_done)
+		rte_delay_ms(10);
+
+	ret = reset_ret;
+
+finish:
+	rte_eth_dev_callback_unregister(pid,
+			RTE_ETH_EVENT_RESET_COMPLETE,
+			on_reset_complete, NULL);
+
+	return ret;
+}
+
 void
 reset_port(portid_t pid)
 {
@@ -1946,7 +1994,7 @@ reset_port(portid_t pid)
 			continue;
 		}
 
-		diag = rte_eth_dev_reset(pi);
+		diag = do_dev_reset_sync(pi);
 		if (diag == 0) {
 			port = &ports[pi];
 			port->need_reconfig = 1;
diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index 4c3202505..69279577d 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -1374,10 +1374,38 @@ rte_eth_dev_close(uint16_t port_id)
 	dev->data->tx_queues = NULL;
 }
 
+struct dev_reset_args {
+	struct rte_eth_dev *dev;
+	enum rte_eth_dev_state pre_state;
+};
+
+static void *
+do_dev_reset(void *args)
+{
+	struct dev_reset_args *reset_args = args;
+	struct rte_eth_dev *dev = reset_args->dev;
+	int ret;
+
+	ret = dev->dev_ops->dev_reset(dev);
+
+	/*restore previous device state */
+	dev->state = reset_args->pre_state;
+
+	/* notify users */
+	_rte_eth_dev_callback_process(dev, RTE_ETH_EVENT_RESET_COMPLETE,
+					&ret);
+
+	free(args);
+	return NULL;
+}
+
 int
-rte_eth_dev_reset(uint16_t port_id)
+rte_eth_dev_reset_async(uint16_t port_id)
 {
 	struct rte_eth_dev *dev;
+	struct dev_reset_args *args;
+	char pthread_name[20];
+	pthread_t tid;
 	int ret;
 
 	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -EINVAL);
@@ -1385,10 +1413,26 @@ rte_eth_dev_reset(uint16_t port_id)
 
 	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->dev_reset, -ENOTSUP);
 
+	/* already on resetting */
+	if (dev->state == RTE_ETH_DEV_RESETTING)
+		return 0;
+
+	args = calloc(1, sizeof(struct dev_reset_args));
+	if (!args)
+		return -ENOMEM;
+
 	rte_eth_dev_stop(port_id);
-	ret = dev->dev_ops->dev_reset(dev);
 
-	return eth_err(port_id, ret);
+	/* store previous device state temporary */
+	args->pre_state = dev->state;
+
+	dev->state = RTE_ETH_DEV_RESETTING;
+	snprintf(pthread_name, sizeof(pthread_name),
+			"do_dev_reset_%d", port_id);
+	ret = rte_ctrl_thread_create(&tid, pthread_name, NULL,
+					do_dev_reset, args);
+
+	return ret;
 }
 
 int __rte_experimental
diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
index 7070e9ab4..95fcb2931 100644
--- a/lib/librte_ethdev/rte_ethdev.h
+++ b/lib/librte_ethdev/rte_ethdev.h
@@ -1239,6 +1239,8 @@ enum rte_eth_dev_state {
 	RTE_ETH_DEV_DEFERRED,
 	/** Device is in removed state when plug-out is detected. */
 	RTE_ETH_DEV_REMOVED,
+	/** Device is on resetting when rte_eth_dev_reset_async is called. */
+	RTE_ETH_DEV_RESETTING,
 };
 
 struct rte_eth_dev_sriov {
@@ -1814,21 +1816,29 @@ void rte_eth_dev_close(uint16_t port_id);
  * RTE_ETH_EVENT_INTR_RESET event is detected, but can also use it to start
  * a port reset in other circumstances.
  *
- * When this function is called, it first stops the port and then calls the
- * PMD specific dev_uninit( ) and dev_init( ) to return the port to initial
- * state, in which no Tx and Rx queues are setup, as if the port has been
- * reset and not started. The port keeps the port id it had before the
- * function call.
- *
- * After calling rte_eth_dev_reset( ), the application should use
- * rte_eth_dev_configure( ), rte_eth_rx_queue_setup( ),
- * rte_eth_tx_queue_setup( ), and rte_eth_dev_start( )
- * to reconfigure the device as appropriate.
- *
- * Note: To avoid unexpected behavior, the application should stop calling
- * Tx and Rx functions before calling rte_eth_dev_reset( ). For thread
- * safety, all these controlling functions should be called from the same
- * thread.
+ * @note
+ * Device reset may have the dependency, for example, a VF reset expects
+ * PF ready, or a NIC function as a part of a SOC need to wait for other
+ * parts of the system be ready, these are time-consuming tasks and will
+ * block current thread.
+ *
+ * As the name, rte_eth_dev_reset_async is an async API, it will spwan a
+ * new thread to call ops->dev_reset, once it is finished, it will raise
+ * the RTE_ETH_EVENT_RESET_COMPLETE event to notify application.  That makes
+ * things easy for an application that what to reset the device from the
+ * interrupt thread since typically a RTE_ETH_EVENT_INTR_RESET handler is
+ * invoked in interrupt thread.
+ *
+ * Application should not assume device reset is finished after
+ * rte_eth_dev_reset_async return, it should always wait for a
+ * RTE_ETH_EVENT_RESET_COMPLETE event and check the reset result.
+ * If reset success, application should call rte_eth_dev_configure( ),
+ * rte_eth_rx_queue_setup( ), rte_eth_tx_queue_setup( ),
+ * and rte_eth_dev_start( ) to reconfigure the device as appropriate.
+ *
+ * @Note
+ * To avoid unexpected behavior, the application should stop calling
+ * Tx and Rx functions before calling rte_eth_dev_reset_async( ).
  *
  * @param port_id
  *   The port identifier of the Ethernet device.
@@ -1837,12 +1847,10 @@ void rte_eth_dev_close(uint16_t port_id);
  *   - (0) if successful.
  *   - (-EINVAL) if port identifier is invalid.
  *   - (-ENOTSUP) if hardware doesn't support this function.
- *   - (-EPERM) if not ran from the primary process.
- *   - (-EIO) if re-initialisation failed or device is removed.
  *   - (-ENOMEM) if the reset failed due to OOM.
- *   - (-EAGAIN) if the reset temporarily failed and should be retried later.
+ *   - (<0) other errors from low level driver.
  */
-int rte_eth_dev_reset(uint16_t port_id);
+int rte_eth_dev_reset_async(uint16_t port_id);
 
 /**
  * Enable receipt in promiscuous mode for an Ethernet device.
@@ -2574,6 +2582,8 @@ enum rte_eth_event_type {
 				/**< queue state event (enabled/disabled) */
 	RTE_ETH_EVENT_INTR_RESET,
 			/**< reset interrupt event, sent to VF on PF reset */
+	RTE_ETH_EVENT_RESET_COMPLETE,
+			/**< inform application that reset is completed */
 	RTE_ETH_EVENT_VF_MBOX,  /**< message from the VF received by PF */
 	RTE_ETH_EVENT_MACSEC,   /**< MACsec offload related event */
 	RTE_ETH_EVENT_INTR_RMV, /**< device removal event */
-- 
2.13.6