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

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

[Qi Zhang]

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>
---

RFC3 -> v1
- fix state check in rte_eth_find_next and rte_eth_find_next_owned_by
- fix compile error in netvsc
- update document and release notes
- improve comments and couple typo fix

 app/test-pmd/testpmd.c                   | 50 +++++++++++++++++++++++++++-
 doc/guides/prog_guide/poll_mode_drv.rst  | 34 ++++++++++++-------
 doc/guides/rel_notes/release_19_05.rst   |  6 ++++
 drivers/net/ixgbe/ixgbe_ethdev.c         |  4 +--
 drivers/net/netvsc/hn_var.h              |  2 +-
 drivers/net/netvsc/hn_vf.c               |  4 +--
 lib/librte_ethdev/rte_ethdev.c           | 56 +++++++++++++++++++++++++++++---
 lib/librte_ethdev/rte_ethdev.h           | 50 +++++++++++++++++-----------
 lib/librte_ethdev/rte_ethdev_version.map |  7 ++++
 9 files changed, 171 insertions(+), 42 deletions(-)

diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
index d9d0c16d4..27ddfdb59 100644
--- a/app/test-pmd/testpmd.c
+++ b/app/test-pmd/testpmd.c
@@ -2232,6 +2232,54 @@ 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)
 {
@@ -2260,7 +2308,7 @@ 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/doc/guides/prog_guide/poll_mode_drv.rst b/doc/guides/prog_guide/poll_mode_drv.rst
index 6fae39f90..a0aa8fb74 100644
--- a/doc/guides/prog_guide/poll_mode_drv.rst
+++ b/doc/guides/prog_guide/poll_mode_drv.rst
@@ -581,7 +581,7 @@ NIC Reset API
 
 .. code-block:: c
 
-    int rte_eth_dev_reset(uint16_t port_id);
+    int rte_eth_dev_reset_sync(uint16_t port_id);
 
 Sometimes a port has to be reset passively. For example when a PF is
 reset, all its VFs should also be reset by the application to make them
@@ -594,7 +594,7 @@ the application should register a callback function to handle these
 events. When a PMD needs to trigger a reset, it can trigger an
 RTE_ETH_EVENT_INTR_RESET event. On receiving an RTE_ETH_EVENT_INTR_RESET
 event, applications can handle it as follows: Stop working queues, stop
-calling Rx and Tx functions, and then call rte_eth_dev_reset(). For
+calling Rx and Tx functions, and then call rte_eth_dev_reset_sync(). For
 thread safety all these operations should be called from the same thread.
 
 For example when PF is reset, the PF sends a message to notify VFs of
@@ -605,13 +605,23 @@ This means that a PF reset triggers an RTE_ETH_EVENT_INTR_RESET
 event within VFs. The function _rte_eth_dev_callback_process() will
 call the registered callback function. The callback function can trigger
 the application to handle all operations the VF reset requires including
-stopping Rx/Tx queues and calling rte_eth_dev_reset().
-
-The rte_eth_dev_reset() itself is a generic function which only does
-some hardware reset operations through calling dev_unint() and
-dev_init(), and itself does not handle synchronization, which is handled
-by application.
-
-The PMD itself should not call rte_eth_dev_reset(). The PMD can trigger
-the application to handle reset event. It is duty of application to
-handle all synchronization before it calls rte_eth_dev_reset().
+stopping Rx/Tx queues and calling rte_eth_dev_reset_async().
+
+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 want to reset the device from the
+interrupt thread since typically a RTE_ETH_EVENT_INTR_RESET handler is
+invoked in interrupt thread. The typical implementation of ops->dev_reset
+will do some hardware reset operations through calling dev_uninit() and
+dev_init().
+
+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.
+
+To avoid unexpected behavior, the application should stop calling
+Tx and Rx functions before calling rte_eth_dev_reset_async().
diff --git a/doc/guides/rel_notes/release_19_05.rst b/doc/guides/rel_notes/release_19_05.rst
index 61a2c7383..4b7fbad39 100644
--- a/doc/guides/rel_notes/release_19_05.rst
+++ b/doc/guides/rel_notes/release_19_05.rst
@@ -91,6 +91,12 @@ New Features
 
   * Added promiscuous mode support.
 
+* **Claim device reset as async API.**
+
+  rte_eth_dev_reset is replaced by rte_eth_dev_reset_async which is implemented
+  as an async API. Application should wait for RTE_ETH_EVENT_RESET_COMPLETE
+  event after invoke the API before continues to configure and restart the
+  device.
 
 Removed Items
 -------------
diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
index 97e10217d..cd1543da0 100644
--- a/drivers/net/ixgbe/ixgbe_ethdev.c
+++ b/drivers/net/ixgbe/ixgbe_ethdev.c
@@ -1631,8 +1631,8 @@ eth_ixgbevf_dev_init(struct rte_eth_dev *eth_dev)
 		PMD_INIT_LOG(ERR, "VF Initialization Failure: %d", diag);
 		/*
 		 * This error code will be propagated to the app by
-		 * rte_eth_dev_reset, so use a public error code rather than
-		 * the internal-only IXGBE_ERR_RESET_FAILED
+		 * rte_eth_dev_reset_async, so use a public error code rather
+		 * than the internal-only IXGBE_ERR_RESET_FAILED
 		 */
 		return -EAGAIN;
 	}
diff --git a/drivers/net/netvsc/hn_var.h b/drivers/net/netvsc/hn_var.h
index 7f3266c45..5344f75c1 100644
--- a/drivers/net/netvsc/hn_var.h
+++ b/drivers/net/netvsc/hn_var.h
@@ -177,7 +177,7 @@ int	hn_vf_configure(struct rte_eth_dev *dev,
 			const struct rte_eth_conf *dev_conf);
 const uint32_t *hn_vf_supported_ptypes(struct rte_eth_dev *dev);
 int	hn_vf_start(struct rte_eth_dev *dev);
-void	hn_vf_reset(struct rte_eth_dev *dev);
+void	hn_vf_reset_async(struct rte_eth_dev *dev);
 void	hn_vf_stop(struct rte_eth_dev *dev);
 void	hn_vf_close(struct rte_eth_dev *dev);
 
diff --git a/drivers/net/netvsc/hn_vf.c b/drivers/net/netvsc/hn_vf.c
index 3f714ec99..ae03455ba 100644
--- a/drivers/net/netvsc/hn_vf.c
+++ b/drivers/net/netvsc/hn_vf.c
@@ -358,9 +358,9 @@ void hn_vf_stop(struct rte_eth_dev *dev)
 		rte_spinlock_unlock(&hv->vf_lock);		\
 	}
 
-void hn_vf_reset(struct rte_eth_dev *dev)
+void hn_vf_reset_async(struct rte_eth_dev *dev)
 {
-	VF_ETHDEV_FUNC(dev, rte_eth_dev_reset);
+	VF_ETHDEV_FUNC(dev, rte_eth_dev_reset_async);
 }
 
 void hn_vf_close(struct rte_eth_dev *dev)
diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index 85c179496..5a6be6a5b 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -331,7 +331,8 @@ rte_eth_find_next(uint16_t port_id)
 {
 	while (port_id < RTE_MAX_ETHPORTS &&
 	       rte_eth_devices[port_id].state != RTE_ETH_DEV_ATTACHED &&
-	       rte_eth_devices[port_id].state != RTE_ETH_DEV_REMOVED)
+	       rte_eth_devices[port_id].state != RTE_ETH_DEV_REMOVED &&
+	       rte_eth_devices[port_id].state != RTE_ETH_DEV_RESETTING)
 		port_id++;
 
 	if (port_id >= RTE_MAX_ETHPORTS)
@@ -556,7 +557,8 @@ rte_eth_find_next_owned_by(uint16_t port_id, const uint64_t owner_id)
 {
 	while (port_id < RTE_MAX_ETHPORTS &&
 	       ((rte_eth_devices[port_id].state != RTE_ETH_DEV_ATTACHED &&
-	       rte_eth_devices[port_id].state != RTE_ETH_DEV_REMOVED) ||
+	       rte_eth_devices[port_id].state != RTE_ETH_DEV_REMOVED &&
+	       rte_eth_devices[port_id].state != RTE_ETH_DEV_RESETTING) ||
 	       rte_eth_devices[port_id].data->owner.id != owner_id))
 		port_id++;
 
@@ -1490,10 +1492,38 @@ 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);
@@ -1501,10 +1531,26 @@ 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 a3c864a13..b02c16ae3 100644
--- a/lib/librte_ethdev/rte_ethdev.h
+++ b/lib/librte_ethdev/rte_ethdev.h
@@ -1308,6 +1308,8 @@ enum rte_eth_dev_state {
 	RTE_ETH_DEV_ATTACHED,
 	/** 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 {
@@ -1857,21 +1859,31 @@ 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 want to reset the device from the
+ * interrupt thread since typically a RTE_ETH_EVENT_INTR_RESET handler is
+ * invoked in interrupt thread. The typical implementation of ops->dev_reset
+ * will do some hardware reset operations through calling dev_uninit() and
+ * dev_init().
+ *
+ * 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.
@@ -1880,12 +1892,10 @@ 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.
@@ -2617,6 +2627,8 @@ 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 */
diff --git a/lib/librte_ethdev/rte_ethdev_version.map b/lib/librte_ethdev/rte_ethdev_version.map
index 92ac3de25..e9f02656a 100644
--- a/lib/librte_ethdev/rte_ethdev_version.map
+++ b/lib/librte_ethdev/rte_ethdev_version.map
@@ -229,6 +229,13 @@ DPDK_18.11 {
 
 } DPDK_18.08;
 
+DPDK_19.05 {
+	global:
+
+	rte_eth_dev_reset_async;
+
+} DPDK_18.08;
+
 EXPERIMENTAL {
 	global:
 
-- 
2.13.6

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

[Qi Zhang]

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>
---

RFC3 -> v1
- fix state check in rte_eth_find_next and rte_eth_find_next_owned_by
- fix compile error in netvsc
- update document and release notes
- improve comments and couple typo fix

 app/test-pmd/testpmd.c                   | 50 +++++++++++++++++++++++++++-
 doc/guides/prog_guide/poll_mode_drv.rst  | 34 ++++++++++++-------
 doc/guides/rel_notes/release_19_05.rst   |  6 ++++
 drivers/net/ixgbe/ixgbe_ethdev.c         |  4 +--
 drivers/net/netvsc/hn_var.h              |  2 +-
 drivers/net/netvsc/hn_vf.c               |  4 +--
 lib/librte_ethdev/rte_ethdev.c           | 56 +++++++++++++++++++++++++++++---
 lib/librte_ethdev/rte_ethdev.h           | 50 +++++++++++++++++-----------
 lib/librte_ethdev/rte_ethdev_version.map |  7 ++++
 9 files changed, 171 insertions(+), 42 deletions(-)

diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
index d9d0c16d4..27ddfdb59 100644
--- a/app/test-pmd/testpmd.c
+++ b/app/test-pmd/testpmd.c
@@ -2232,6 +2232,54 @@ 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)
 {
@@ -2260,7 +2308,7 @@ 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/doc/guides/prog_guide/poll_mode_drv.rst b/doc/guides/prog_guide/poll_mode_drv.rst
index 6fae39f90..a0aa8fb74 100644
--- a/doc/guides/prog_guide/poll_mode_drv.rst
+++ b/doc/guides/prog_guide/poll_mode_drv.rst
@@ -581,7 +581,7 @@ NIC Reset API
 
 .. code-block:: c
 
-    int rte_eth_dev_reset(uint16_t port_id);
+    int rte_eth_dev_reset_sync(uint16_t port_id);
 
 Sometimes a port has to be reset passively. For example when a PF is
 reset, all its VFs should also be reset by the application to make them
@@ -594,7 +594,7 @@ the application should register a callback function to handle these
 events. When a PMD needs to trigger a reset, it can trigger an
 RTE_ETH_EVENT_INTR_RESET event. On receiving an RTE_ETH_EVENT_INTR_RESET
 event, applications can handle it as follows: Stop working queues, stop
-calling Rx and Tx functions, and then call rte_eth_dev_reset(). For
+calling Rx and Tx functions, and then call rte_eth_dev_reset_sync(). For
 thread safety all these operations should be called from the same thread.
 
 For example when PF is reset, the PF sends a message to notify VFs of
@@ -605,13 +605,23 @@ This means that a PF reset triggers an RTE_ETH_EVENT_INTR_RESET
 event within VFs. The function _rte_eth_dev_callback_process() will
 call the registered callback function. The callback function can trigger
 the application to handle all operations the VF reset requires including
-stopping Rx/Tx queues and calling rte_eth_dev_reset().
-
-The rte_eth_dev_reset() itself is a generic function which only does
-some hardware reset operations through calling dev_unint() and
-dev_init(), and itself does not handle synchronization, which is handled
-by application.
-
-The PMD itself should not call rte_eth_dev_reset(). The PMD can trigger
-the application to handle reset event. It is duty of application to
-handle all synchronization before it calls rte_eth_dev_reset().
+stopping Rx/Tx queues and calling rte_eth_dev_reset_async().
+
+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 want to reset the device from the
+interrupt thread since typically a RTE_ETH_EVENT_INTR_RESET handler is
+invoked in interrupt thread. The typical implementation of ops->dev_reset
+will do some hardware reset operations through calling dev_uninit() and
+dev_init().
+
+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.
+
+To avoid unexpected behavior, the application should stop calling
+Tx and Rx functions before calling rte_eth_dev_reset_async().
diff --git a/doc/guides/rel_notes/release_19_05.rst b/doc/guides/rel_notes/release_19_05.rst
index 61a2c7383..4b7fbad39 100644
--- a/doc/guides/rel_notes/release_19_05.rst
+++ b/doc/guides/rel_notes/release_19_05.rst
@@ -91,6 +91,12 @@ New Features
 
   * Added promiscuous mode support.
 
+* **Claim device reset as async API.**
+
+  rte_eth_dev_reset is replaced by rte_eth_dev_reset_async which is implemented
+  as an async API. Application should wait for RTE_ETH_EVENT_RESET_COMPLETE
+  event after invoke the API before continues to configure and restart the
+  device.
 
 Removed Items
 -------------
diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
index 97e10217d..cd1543da0 100644
--- a/drivers/net/ixgbe/ixgbe_ethdev.c
+++ b/drivers/net/ixgbe/ixgbe_ethdev.c
@@ -1631,8 +1631,8 @@ eth_ixgbevf_dev_init(struct rte_eth_dev *eth_dev)
 		PMD_INIT_LOG(ERR, "VF Initialization Failure: %d", diag);
 		/*
 		 * This error code will be propagated to the app by
-		 * rte_eth_dev_reset, so use a public error code rather than
-		 * the internal-only IXGBE_ERR_RESET_FAILED
+		 * rte_eth_dev_reset_async, so use a public error code rather
+		 * than the internal-only IXGBE_ERR_RESET_FAILED
 		 */
 		return -EAGAIN;
 	}
diff --git a/drivers/net/netvsc/hn_var.h b/drivers/net/netvsc/hn_var.h
index 7f3266c45..5344f75c1 100644
--- a/drivers/net/netvsc/hn_var.h
+++ b/drivers/net/netvsc/hn_var.h
@@ -177,7 +177,7 @@ int	hn_vf_configure(struct rte_eth_dev *dev,
 			const struct rte_eth_conf *dev_conf);
 const uint32_t *hn_vf_supported_ptypes(struct rte_eth_dev *dev);
 int	hn_vf_start(struct rte_eth_dev *dev);
-void	hn_vf_reset(struct rte_eth_dev *dev);
+void	hn_vf_reset_async(struct rte_eth_dev *dev);
 void	hn_vf_stop(struct rte_eth_dev *dev);
 void	hn_vf_close(struct rte_eth_dev *dev);
 
diff --git a/drivers/net/netvsc/hn_vf.c b/drivers/net/netvsc/hn_vf.c
index 3f714ec99..ae03455ba 100644
--- a/drivers/net/netvsc/hn_vf.c
+++ b/drivers/net/netvsc/hn_vf.c
@@ -358,9 +358,9 @@ void hn_vf_stop(struct rte_eth_dev *dev)
 		rte_spinlock_unlock(&hv->vf_lock);		\
 	}
 
-void hn_vf_reset(struct rte_eth_dev *dev)
+void hn_vf_reset_async(struct rte_eth_dev *dev)
 {
-	VF_ETHDEV_FUNC(dev, rte_eth_dev_reset);
+	VF_ETHDEV_FUNC(dev, rte_eth_dev_reset_async);
 }
 
 void hn_vf_close(struct rte_eth_dev *dev)
diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index 85c179496..5a6be6a5b 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -331,7 +331,8 @@ rte_eth_find_next(uint16_t port_id)
 {
 	while (port_id < RTE_MAX_ETHPORTS &&
 	       rte_eth_devices[port_id].state != RTE_ETH_DEV_ATTACHED &&
-	       rte_eth_devices[port_id].state != RTE_ETH_DEV_REMOVED)
+	       rte_eth_devices[port_id].state != RTE_ETH_DEV_REMOVED &&
+	       rte_eth_devices[port_id].state != RTE_ETH_DEV_RESETTING)
 		port_id++;
 
 	if (port_id >= RTE_MAX_ETHPORTS)
@@ -556,7 +557,8 @@ rte_eth_find_next_owned_by(uint16_t port_id, const uint64_t owner_id)
 {
 	while (port_id < RTE_MAX_ETHPORTS &&
 	       ((rte_eth_devices[port_id].state != RTE_ETH_DEV_ATTACHED &&
-	       rte_eth_devices[port_id].state != RTE_ETH_DEV_REMOVED) ||
+	       rte_eth_devices[port_id].state != RTE_ETH_DEV_REMOVED &&
+	       rte_eth_devices[port_id].state != RTE_ETH_DEV_RESETTING) ||
 	       rte_eth_devices[port_id].data->owner.id != owner_id))
 		port_id++;
 
@@ -1490,10 +1492,38 @@ 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);
@@ -1501,10 +1531,26 @@ 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 a3c864a13..b02c16ae3 100644
--- a/lib/librte_ethdev/rte_ethdev.h
+++ b/lib/librte_ethdev/rte_ethdev.h
@@ -1308,6 +1308,8 @@ enum rte_eth_dev_state {
 	RTE_ETH_DEV_ATTACHED,
 	/** 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 {
@@ -1857,21 +1859,31 @@ 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 want to reset the device from the
+ * interrupt thread since typically a RTE_ETH_EVENT_INTR_RESET handler is
+ * invoked in interrupt thread. The typical implementation of ops->dev_reset
+ * will do some hardware reset operations through calling dev_uninit() and
+ * dev_init().
+ *
+ * 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.
@@ -1880,12 +1892,10 @@ 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.
@@ -2617,6 +2627,8 @@ 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 */
diff --git a/lib/librte_ethdev/rte_ethdev_version.map b/lib/librte_ethdev/rte_ethdev_version.map
index 92ac3de25..e9f02656a 100644
--- a/lib/librte_ethdev/rte_ethdev_version.map
+++ b/lib/librte_ethdev/rte_ethdev_version.map
@@ -229,6 +229,13 @@ DPDK_18.11 {
 
 } DPDK_18.08;
 
+DPDK_19.05 {
+	global:
+
+	rte_eth_dev_reset_async;
+
+} DPDK_18.08;
+
 EXPERIMENTAL {
 	global:
 
-- 
2.13.6

Re: [dpdk-dev] [PATCH] ethdev: claim device reset as async

[Stephen Hemminger]

On Wed, 20 Mar 2019 12:54:03 +0800
Qi Zhang <qi.z.zhang@intel.com> wrote:

> +	ret = rte_ctrl_thread_create(&tid, pthread_name, NULL,
> +					do_dev_reset, args);
> +
> +	return ret;

combine the ret = and return (ie make it a tail call)

Re: [dpdk-dev] [PATCH] ethdev: claim device reset as async

[Stephen Hemminger]

On Wed, 20 Mar 2019 12:54:03 +0800
Qi Zhang <qi.z.zhang@intel.com> wrote:

> +	ret = rte_ctrl_thread_create(&tid, pthread_name, NULL,
> +					do_dev_reset, args);
> +
> +	return ret;

combine the ret = and return (ie make it a tail call)

Re: [dpdk-dev] [PATCH] ethdev: claim device reset as async

[Thomas Monjalon]

Hi,

You forgot to Cc Andrew, co-maintainer of ethdev.

20/03/2019 05:54, Qi Zhang:
> 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>
> ---
> - * 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 want to reset the device from the
> + * interrupt thread since typically a RTE_ETH_EVENT_INTR_RESET handler is
> + * invoked in interrupt thread. The typical implementation of ops->dev_reset
> + * will do some hardware reset operations through calling dev_uninit() and
> + * dev_init().
> + *
> + * 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.
> @@ -1880,12 +1892,10 @@ 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);

Sorry I didn't check whether this API is better or not,
but I know it cannot be accepted before proposing a deprecation notice.
Perhaps you may keep the old API and just add the new one.

Honestly, I never really agreed with the purpose of the reset API.
So making it async or not, I have no real opinion...
... but spawning a new thread at each function call, I feel it is bad.

Re: [dpdk-dev] [PATCH] ethdev: claim device reset as async

[Thomas Monjalon]

Hi,

You forgot to Cc Andrew, co-maintainer of ethdev.

20/03/2019 05:54, Qi Zhang:
> 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>
> ---
> - * 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 want to reset the device from the
> + * interrupt thread since typically a RTE_ETH_EVENT_INTR_RESET handler is
> + * invoked in interrupt thread. The typical implementation of ops->dev_reset
> + * will do some hardware reset operations through calling dev_uninit() and
> + * dev_init().
> + *
> + * 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.
> @@ -1880,12 +1892,10 @@ 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);

Sorry I didn't check whether this API is better or not,
but I know it cannot be accepted before proposing a deprecation notice.
Perhaps you may keep the old API and just add the new one.

Honestly, I never really agreed with the purpose of the reset API.
So making it async or not, I have no real opinion...
... but spawning a new thread at each function call, I feel it is bad.

Re: [dpdk-dev] [PATCH] ethdev: claim device reset as async

[Andrew Rybchenko]

On 4/5/19 1:01 AM, Thomas Monjalon wrote:
> Hi,
>
> You forgot to Cc Andrew, co-maintainer of ethdev.
>
> 20/03/2019 05:54, Qi Zhang:
>> 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>
>> ---
>> - * 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 want to reset the device from the
>> + * interrupt thread since typically a RTE_ETH_EVENT_INTR_RESET handler is
>> + * invoked in interrupt thread. The typical implementation of ops->dev_reset
>> + * will do some hardware reset operations through calling dev_uninit() and
>> + * dev_init().
>> + *
>> + * 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.
>> @@ -1880,12 +1892,10 @@ 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);
> Sorry I didn't check whether this API is better or not,
> but I know it cannot be accepted before proposing a deprecation notice.
> Perhaps you may keep the old API and just add the new one.
>
> Honestly, I never really agreed with the purpose of the reset API.
> So making it async or not, I have no real opinion...
> ... but spawning a new thread at each function call, I feel it is bad.

I agree with Thomas.

It looks very dangerous from locking point of view when a PMD
callback is executed from dynamically created thread.

Re: [dpdk-dev] [PATCH] ethdev: claim device reset as async

[Andrew Rybchenko]

On 4/5/19 1:01 AM, Thomas Monjalon wrote:
> Hi,
>
> You forgot to Cc Andrew, co-maintainer of ethdev.
>
> 20/03/2019 05:54, Qi Zhang:
>> 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>
>> ---
>> - * 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 want to reset the device from the
>> + * interrupt thread since typically a RTE_ETH_EVENT_INTR_RESET handler is
>> + * invoked in interrupt thread. The typical implementation of ops->dev_reset
>> + * will do some hardware reset operations through calling dev_uninit() and
>> + * dev_init().
>> + *
>> + * 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.
>> @@ -1880,12 +1892,10 @@ 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);
> Sorry I didn't check whether this API is better or not,
> but I know it cannot be accepted before proposing a deprecation notice.
> Perhaps you may keep the old API and just add the new one.
>
> Honestly, I never really agreed with the purpose of the reset API.
> So making it async or not, I have no real opinion...
> ... but spawning a new thread at each function call, I feel it is bad.

I agree with Thomas.

It looks very dangerous from locking point of view when a PMD
callback is executed from dynamically created thread.