[dpdk-dev] [PATCH] kni: add support for core_id param in single threaded mode

[Vladyslav Buslov <vladyslav.buslov@harmonicinc.com>]

Allow binding KNI thread to specific core in single threaded mode
by setting core_id and force_bind config parameters.

Signed-off-by: Vladyslav Buslov <vladyslav.buslov@harmonicinc.com>
---
 doc/guides/prog_guide/kernel_nic_interface.rst |   3 +
 lib/librte_eal/linuxapp/kni/kni_misc.c         | 101 ++++++++++++++++---------
 2 files changed, 67 insertions(+), 37 deletions(-)

diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/prog_guide/kernel_nic_interface.rst
index fac1960..eb16e2e 100644
--- a/doc/guides/prog_guide/kernel_nic_interface.rst
+++ b/doc/guides/prog_guide/kernel_nic_interface.rst
@@ -102,6 +102,9 @@ Refer to rte_kni_common.h in the DPDK source code for more details.
 
 The physical addresses will be re-mapped into the kernel address space and stored in separate KNI contexts.
 
+The affinity of kernel RX thread (both single and multi-threaded modes) is controlled by force_bind and
+core_id config parameters.
+
 The KNI interfaces can be deleted by a DPDK application dynamically after being created.
 Furthermore, all those KNI interfaces not deleted will be deleted on the release operation
 of the miscellaneous device (when the DPDK application is closed).
diff --git a/lib/librte_eal/linuxapp/kni/kni_misc.c b/lib/librte_eal/linuxapp/kni/kni_misc.c
index 59d15ca..056e13b 100644
--- a/lib/librte_eal/linuxapp/kni/kni_misc.c
+++ b/lib/librte_eal/linuxapp/kni/kni_misc.c
@@ -30,6 +30,7 @@
 #include <linux/pci.h>
 #include <linux/kthread.h>
 #include <linux/rwsem.h>
+#include <linux/mutex.h>
 #include <linux/nsproxy.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
@@ -100,6 +101,7 @@ static int kni_net_id;
 
 struct kni_net {
 	unsigned long device_in_use; /* device in use flag */
+	struct mutex kni_kthread_lock;
 	struct task_struct *kni_kthread;
 	struct rw_semaphore kni_list_lock;
 	struct list_head kni_list_head;
@@ -123,6 +125,9 @@ static int __net_init kni_init_net(struct net *net)
 	/* Clear the bit of device in use */
 	clear_bit(KNI_DEV_IN_USE_BIT_NUM, &knet->device_in_use);
 
+	mutex_init(&knet->kni_kthread_lock);
+	knet->kni_kthread = NULL;
+
 	init_rwsem(&knet->kni_list_lock);
 	INIT_LIST_HEAD(&knet->kni_list_head);
 
@@ -139,9 +144,9 @@ static int __net_init kni_init_net(struct net *net)
 
 static void __net_exit kni_exit_net(struct net *net)
 {
-#ifndef HAVE_SIMPLIFIED_PERNET_OPERATIONS
 	struct kni_net *knet = net_generic(net, kni_net_id);
-
+	mutex_destroy(&knet->kni_kthread_lock);
+#ifndef HAVE_SIMPLIFIED_PERNET_OPERATIONS
 	kfree(knet);
 #endif
 }
@@ -167,6 +172,11 @@ kni_init(void)
 		return -EINVAL;
 	}
 
+	if (multiple_kthread_on == 0)
+		KNI_PRINT("Single kernel thread for all KNI devices\n");
+	else
+		KNI_PRINT("Multiple kernel thread mode enabled\n");
+
 #ifdef HAVE_SIMPLIFIED_PERNET_OPERATIONS
 	rc = register_pernet_subsys(&kni_net_ops);
 #else
@@ -235,19 +245,6 @@ kni_open(struct inode *inode, struct file *file)
 	if (test_and_set_bit(KNI_DEV_IN_USE_BIT_NUM, &knet->device_in_use))
 		return -EBUSY;
 
-	/* Create kernel thread for single mode */
-	if (multiple_kthread_on == 0) {
-		KNI_PRINT("Single kernel thread for all KNI devices\n");
-		/* Create kernel thread for RX */
-		knet->kni_kthread = kthread_run(kni_thread_single, (void *)knet,
-						"kni_single");
-		if (IS_ERR(knet->kni_kthread)) {
-			KNI_ERR("Unable to create kernel threaed\n");
-			return PTR_ERR(knet->kni_kthread);
-		}
-	} else
-		KNI_PRINT("Multiple kernel thread mode enabled\n");
-
 	file->private_data = get_net(net);
 	KNI_PRINT("/dev/kni opened\n");
 
@@ -263,9 +260,13 @@ kni_release(struct inode *inode, struct file *file)
 
 	/* Stop kernel thread for single mode */
 	if (multiple_kthread_on == 0) {
+		mutex_lock(&knet->kni_kthread_lock);
 		/* Stop kernel thread */
-		kthread_stop(knet->kni_kthread);
-		knet->kni_kthread = NULL;
+		if (knet->kni_kthread != NULL) {
+			kthread_stop(knet->kni_kthread);
+			knet->kni_kthread = NULL;
+		}
+		mutex_unlock(&knet->kni_kthread_lock);
 	}
 
 	down_write(&knet->kni_list_lock);
@@ -390,6 +391,47 @@ kni_check_param(struct kni_dev *kni, struct rte_kni_device_info *dev)
 }
 
 static int
+kni_run_thread(struct kni_net *knet, struct kni_dev *kni, uint8_t force_bind)
+{
+	/**
+	 * Create a new kernel thread for multiple mode, set its core affinity,
+	 * and finally wake it up.
+	 */
+	if (multiple_kthread_on) {
+		kni->pthread = kthread_create(kni_thread_multiple,
+			(void *)kni, "kni_%s", kni->name);
+		if (IS_ERR(kni->pthread)) {
+			kni_dev_remove(kni);
+			return -ECANCELED;
+		}
+
+		if (force_bind)
+			kthread_bind(kni->pthread, kni->core_id);
+		wake_up_process(kni->pthread);
+	} else {
+		mutex_lock(&knet->kni_kthread_lock);
+
+		if (knet->kni_kthread == NULL) {
+			knet->kni_kthread = kthread_create(kni_thread_single,
+				(void *)knet, "kni_single");
+			if (IS_ERR(knet->kni_kthread)) {
+				mutex_unlock(&knet->kni_kthread_lock);
+				kni_dev_remove(kni);
+				return -ECANCELED;
+			}
+
+			if (force_bind)
+				kthread_bind(knet->kni_kthread, kni->core_id);
+			wake_up_process(knet->kni_kthread);
+		}
+
+		mutex_unlock(&knet->kni_kthread_lock);
+	}
+
+	return 0;
+}
+
+static int
 kni_ioctl_create(struct net *net,
 		unsigned int ioctl_num, unsigned long ioctl_param)
 {
@@ -415,11 +457,9 @@ kni_ioctl_create(struct net *net,
 	}
 
 	/**
-	 * Check if the cpu core id is valid for binding,
-	 * for multiple kernel thread mode.
+	 * Check if the cpu core id is valid for binding.
 	 */
-	if (multiple_kthread_on && dev_info.force_bind &&
-				!cpu_online(dev_info.core_id)) {
+	if (dev_info.force_bind && !cpu_online(dev_info.core_id)) {
 		KNI_ERR("cpu %u is not online\n", dev_info.core_id);
 		return -EINVAL;
 	}
@@ -566,22 +606,9 @@ kni_ioctl_create(struct net *net,
 	kni_vhost_init(kni);
 #endif
 
-	/**
-	 * Create a new kernel thread for multiple mode, set its core affinity,
-	 * and finally wake it up.
-	 */
-	if (multiple_kthread_on) {
-		kni->pthread = kthread_create(kni_thread_multiple,
-					      (void *)kni,
-					      "kni_%s", kni->name);
-		if (IS_ERR(kni->pthread)) {
-			kni_dev_remove(kni);
-			return -ECANCELED;
-		}
-		if (dev_info.force_bind)
-			kthread_bind(kni->pthread, kni->core_id);
-		wake_up_process(kni->pthread);
-	}
+	ret = kni_run_thread(knet, kni, dev_info.force_bind);
+	if (ret != 0)
+		return ret;
 
 	down_write(&knet->kni_list_lock);
 	list_add(&kni->list, &knet->kni_list_head);
-- 
2.8.3