1 files changed, 199 insertions, 47 deletions

diff --git a/drivers/scsi/fcoe/libfcoe.c b/drivers/scsi/fcoe/libfcoe.c
index 648a2fc0427..951d2448ad6 100644
--- a/drivers/scsi/fcoe/libfcoe.c
+++ b/drivers/scsi/fcoe/libfcoe.c
@@ -81,6 +81,156 @@ static struct notifier_block fcoe_notifier = {
 };
 
 /**
+ * fcoe_percpu_thread_create() - Create a receive thread for an online cpu
+ * @cpu: cpu index for the online cpu
+ */
+static void fcoe_percpu_thread_create(unsigned int cpu)
+{
+	struct fcoe_percpu_s *p;
+	struct task_struct *thread;
+
+	p = &per_cpu(fcoe_percpu, cpu);
+
+	thread = kthread_create(fcoe_percpu_receive_thread,
+				(void *)p, "fcoethread/%d", cpu);
+
+	if (likely(!IS_ERR(p->thread))) {
+		kthread_bind(thread, cpu);
+		wake_up_process(thread);
+
+		spin_lock_bh(&p->fcoe_rx_list.lock);
+		p->thread = thread;
+		spin_unlock_bh(&p->fcoe_rx_list.lock);
+	}
+}
+
+/**
+ * fcoe_percpu_thread_destroy() - removes the rx thread for the given cpu
+ * @cpu: cpu index the rx thread is to be removed
+ *
+ * Destroys a per-CPU Rx thread. Any pending skbs are moved to the
+ * current CPU's Rx thread. If the thread being destroyed is bound to
+ * the CPU processing this context the skbs will be freed.
+ */
+static void fcoe_percpu_thread_destroy(unsigned int cpu)
+{
+	struct fcoe_percpu_s *p;
+	struct task_struct *thread;
+	struct page *crc_eof;
+	struct sk_buff *skb;
+#ifdef CONFIG_SMP
+	struct fcoe_percpu_s *p0;
+	unsigned targ_cpu = smp_processor_id();
+#endif /* CONFIG_SMP */
+
+	printk(KERN_DEBUG "fcoe: Destroying receive thread for CPU %d\n", cpu);
+
+	/* Prevent any new skbs from being queued for this CPU. */
+	p = &per_cpu(fcoe_percpu, cpu);
+	spin_lock_bh(&p->fcoe_rx_list.lock);
+	thread = p->thread;
+	p->thread = NULL;
+	crc_eof = p->crc_eof_page;
+	p->crc_eof_page = NULL;
+	p->crc_eof_offset = 0;
+	spin_unlock_bh(&p->fcoe_rx_list.lock);
+
+#ifdef CONFIG_SMP
+	/*
+	 * Don't bother moving the skb's if this context is running
+	 * on the same CPU that is having its thread destroyed. This
+	 * can easily happen when the module is removed.
+	 */
+	if (cpu != targ_cpu) {
+		p0 = &per_cpu(fcoe_percpu, targ_cpu);
+		spin_lock_bh(&p0->fcoe_rx_list.lock);
+		if (p0->thread) {
+			FC_DBG("Moving frames from CPU %d to CPU %d\n",
+			       cpu, targ_cpu);
+
+			while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
+				__skb_queue_tail(&p0->fcoe_rx_list, skb);
+			spin_unlock_bh(&p0->fcoe_rx_list.lock);
+		} else {
+			/*
+			 * The targeted CPU is not initialized and cannot accept
+			 * new  skbs. Unlock the targeted CPU and drop the skbs
+			 * on the CPU that is going offline.
+			 */
+			while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
+				kfree_skb(skb);
+			spin_unlock_bh(&p0->fcoe_rx_list.lock);
+		}
+	} else {
+		/*
+		 * This scenario occurs when the module is being removed
+		 * and all threads are being destroyed. skbs will continue
+		 * to be shifted from the CPU thread that is being removed
+		 * to the CPU thread associated with the CPU that is processing
+		 * the module removal. Once there is only one CPU Rx thread it
+		 * will reach this case and we will drop all skbs and later
+		 * stop the thread.
+		 */
+		spin_lock_bh(&p->fcoe_rx_list.lock);
+		while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
+			kfree_skb(skb);
+		spin_unlock_bh(&p->fcoe_rx_list.lock);
+	}
+#else
+	/*
+	 * This a non-SMP scenario where the singluar Rx thread is
+	 * being removed. Free all skbs and stop the thread.
+	 */
+	spin_lock_bh(&p->fcoe_rx_list.lock);
+	while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
+		kfree_skb(skb);
+	spin_unlock_bh(&p->fcoe_rx_list.lock);
+#endif
+
+	if (thread)
+		kthread_stop(thread);
+
+	if (crc_eof)
+		put_page(crc_eof);
+}
+
+/**
+ * fcoe_cpu_callback() - fcoe cpu hotplug event callback
+ * @nfb: callback data block
+ * @action: event triggering the callback
+ * @hcpu: index for the cpu of this event
+ *
+ * This creates or destroys per cpu data for fcoe
+ *
+ * Returns NOTIFY_OK always.
+ */
+static int fcoe_cpu_callback(struct notifier_block *nfb,
+			     unsigned long action, void *hcpu)
+{
+	unsigned cpu = (unsigned long)hcpu;
+
+	switch (action) {
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+		FC_DBG("CPU %x online: Create Rx thread\n", cpu);
+		fcoe_percpu_thread_create(cpu);
+		break;
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		FC_DBG("CPU %x offline: Remove Rx thread\n", cpu);
+		fcoe_percpu_thread_destroy(cpu);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block fcoe_cpu_notifier = {
+	.notifier_call = fcoe_cpu_callback,
+};
+
+/**
  * fcoe_rcv() - this is the fcoe receive function called by NET_RX_SOFTIRQ
  * @skb: the receive skb
  * @dev: associated net device
@@ -100,7 +250,7 @@ int fcoe_rcv(struct sk_buff *skb, struct net_device *dev,
 	struct fc_frame_header *fh;
 	struct fcoe_percpu_s *fps;
 	unsigned short oxid;
-	unsigned int cpu_idx;
+	unsigned int cpu = 0;
 
 	fc = container_of(ptype, struct fcoe_softc, fcoe_packet_type);
 	lp = fc->lp;
@@ -140,25 +290,42 @@ int fcoe_rcv(struct sk_buff *skb, struct net_device *dev,
 	fr = fcoe_dev_from_skb(skb);
 	fr->fr_dev = lp;
 	fr->ptype = ptype;
-	cpu_idx = 0;
 
 #ifdef CONFIG_SMP
 	/*
 	 * The incoming frame exchange id(oxid) is ANDed with num of online
-	 * cpu bits to get cpu_idx and then this cpu_idx is used for selecting
-	 * a per cpu kernel thread from fcoe_percpu. In case the cpu is
-	 * offline or no kernel thread for derived cpu_idx then cpu_idx is
-	 * initialize to first online cpu index.
+	 * cpu bits to get cpu and then this cpu is used for selecting
+	 * a per cpu kernel thread from fcoe_percpu.
 	 */
-	cpu_idx = oxid & (num_online_cpus() - 1);
-	if (!cpu_online(cpu_idx))
-		cpu_idx = first_cpu(cpu_online_map);
-
+	cpu = oxid & (num_online_cpus() - 1);
 #endif
 
-	fps = &per_cpu(fcoe_percpu, cpu_idx);
-
+	fps = &per_cpu(fcoe_percpu, cpu);
 	spin_lock_bh(&fps->fcoe_rx_list.lock);
+	if (unlikely(!fps->thread)) {
+		/*
+		 * The targeted CPU is not ready, let's target
+		 * the first CPU now. For non-SMP systems this
+		 * will check the same CPU twice.
+		 */
+		FC_DBG("CPU is online, but no receive thread ready "
+		       "for incoming skb- using first online CPU.\n");
+
+		spin_unlock_bh(&fps->fcoe_rx_list.lock);
+		cpu = first_cpu(cpu_online_map);
+		fps = &per_cpu(fcoe_percpu, cpu);
+		spin_lock_bh(&fps->fcoe_rx_list.lock);
+		if (!fps->thread) {
+			spin_unlock_bh(&fps->fcoe_rx_list.lock);
+			goto err;
+		}
+	}
+
+	/*
+	 * We now have a valid CPU that we're targeting for
+	 * this skb. We also have this receive thread locked,
+	 * so we're free to queue skbs into it's queue.
+	 */
 	__skb_queue_tail(&fps->fcoe_rx_list, skb);
 	if (fps->fcoe_rx_list.qlen == 1)
 		wake_up_process(fps->thread);
@@ -214,7 +381,7 @@ static int fcoe_get_paged_crc_eof(struct sk_buff *skb, int tlen)
 			return -ENOMEM;
 		}
 		fps->crc_eof_page = page;
-		WARN_ON(fps->crc_eof_offset != 0);
+		fps->crc_eof_offset = 0;
 	}
 
 	get_page(page);
@@ -1271,6 +1438,7 @@ EXPORT_SYMBOL_GPL(fcoe_libfc_config);
 static int __init fcoe_init(void)
 {
 	unsigned int cpu;
+	int rc = 0;
 	struct fcoe_percpu_s *p;
 
 	INIT_LIST_HEAD(&fcoe_hostlist);
@@ -1281,29 +1449,15 @@ static int __init fcoe_init(void)
 		skb_queue_head_init(&p->fcoe_rx_list);
 	}
 
-	/*
-	 * initialize per CPU interrupt thread
-	 */
-	for_each_online_cpu(cpu) {
-		p = &per_cpu(fcoe_percpu, cpu);
-		p->thread = kthread_create(fcoe_percpu_receive_thread,
-					   (void *)p, "fcoethread/%d", cpu);
+	for_each_online_cpu(cpu)
+		fcoe_percpu_thread_create(cpu);
 
-		/*
-		 * If there is no error then bind the thread to the CPU
-		 * and wake it up.
-		 */
-		if (!IS_ERR(p->thread)) {
-			kthread_bind(p->thread, cpu);
-			wake_up_process(p->thread);
-		} else {
-			p->thread = NULL;
-		}
-	}
+	/* Initialize per CPU interrupt thread */
+	rc = register_hotcpu_notifier(&fcoe_cpu_notifier);
+	if (rc)
+		goto out_free;
 
-	/*
-	 * setup link change notification
-	 */
+	/* Setup link change notification */
 	fcoe_dev_setup();
 
 	setup_timer(&fcoe_timer, fcoe_watchdog, 0);
@@ -1316,6 +1470,13 @@ static int __init fcoe_init(void)
 	fcoe_sw_init();
 
 	return 0;
+
+out_free:
+	for_each_online_cpu(cpu) {
+		fcoe_percpu_thread_destroy(cpu);
+	}
+
+	return rc;
 }
 module_init(fcoe_init);
 
@@ -1328,8 +1489,6 @@ static void __exit fcoe_exit(void)
 {
 	unsigned int cpu;
 	struct fcoe_softc *fc, *tmp;
-	struct fcoe_percpu_s *p;
-	struct sk_buff *skb;
 
 	fcoe_dev_cleanup();
 
@@ -1340,17 +1499,10 @@ static void __exit fcoe_exit(void)
 	list_for_each_entry_safe(fc, tmp, &fcoe_hostlist, list)
 		fcoe_transport_release(fc->real_dev);
 
-	for_each_possible_cpu(cpu) {
-		p = &per_cpu(fcoe_percpu, cpu);
-		if (p->thread) {
-			kthread_stop(p->thread);
-			spin_lock_bh(&p->fcoe_rx_list.lock);
-			while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
-				kfree_skb(skb);
-			spin_unlock_bh(&p->fcoe_rx_list.lock);
-			if (p->crc_eof_page)
-				put_page(p->crc_eof_page);
-		}
+	unregister_hotcpu_notifier(&fcoe_cpu_notifier);
+
+	for_each_online_cpu(cpu) {
+		fcoe_percpu_thread_destroy(cpu);
 	}
 
 	/* remove sw trasnport */