[patch 4/5] scsi/bnx2fc: Simplify CPU hotplug code

[Thomas Gleixner]

The CPU hotplug related code of this driver can be simplified by:

1) Consolidating the callbacks into a single state. The CPU thread can be
   torn down on the CPU which goes offline. There is no point in delaying
   that to the CPU dead state

2) Let the core code invoke the online/offline callbacks and remove the
   extra for_each_online_cpu() loops.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 drivers/scsi/bnx2fc/bnx2fc_fcoe.c |   69 ++++++++------------------------------
 include/linux/cpuhotplug.h        |    1 
 2 files changed, 15 insertions(+), 55 deletions(-)

--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -2624,12 +2624,11 @@ static struct fcoe_transport bnx2fc_tran
 };
 
 /**
- * bnx2fc_percpu_thread_create - Create a receive thread for an
- *				 online CPU
+ * bnx2fc_cpu_online - Create a receive thread for an  online CPU
  *
  * @cpu: cpu index for the online cpu
  */
-static void bnx2fc_percpu_thread_create(unsigned int cpu)
+static int bnx2fc_cpu_online(unsigned int cpu)
 {
 	struct bnx2fc_percpu_s *p;
 	struct task_struct *thread;
@@ -2639,15 +2638,17 @@ static void bnx2fc_percpu_thread_create(
 	thread = kthread_create_on_node(bnx2fc_percpu_io_thread,
 					(void *)p, cpu_to_node(cpu),
 					"bnx2fc_thread/%d", cpu);
+	if (IS_ERR(thread))
+		return PTR_ERR(thread);
+
 	/* bind thread to the cpu */
-	if (likely(!IS_ERR(thread))) {
-		kthread_bind(thread, cpu);
-		p->iothread = thread;
-		wake_up_process(thread);
-	}
+	kthread_bind(thread, cpu);
+	p->iothread = thread;
+	wake_up_process(thread);
+	return 0;
 }
 
-static void bnx2fc_percpu_thread_destroy(unsigned int cpu)
+static int bnx2fc_cpu_offline(unsigned int cpu)
 {
 	struct bnx2fc_percpu_s *p;
 	struct task_struct *thread;
@@ -2661,7 +2662,6 @@ static void bnx2fc_percpu_thread_destroy
 	thread = p->iothread;
 	p->iothread = NULL;
 
-
 	/* Free all work in the list */
 	list_for_each_entry_safe(work, tmp, &p->work_list, list) {
 		list_del_init(&work->list);
@@ -2673,20 +2673,6 @@ static void bnx2fc_percpu_thread_destroy
 
 	if (thread)
 		kthread_stop(thread);
-}
-
-
-static int bnx2fc_cpu_online(unsigned int cpu)
-{
-	printk(PFX "CPU %x online: Create Rx thread\n", cpu);
-	bnx2fc_percpu_thread_create(cpu);
-	return 0;
-}
-
-static int bnx2fc_cpu_dead(unsigned int cpu)
-{
-	printk(PFX "CPU %x offline: Remove Rx thread\n", cpu);
-	bnx2fc_percpu_thread_destroy(cpu);
 	return 0;
 }
 
@@ -2761,31 +2747,16 @@ static int __init bnx2fc_mod_init(void)
 		spin_lock_init(&p->fp_work_lock);
 	}
 
-	get_online_cpus();
-
-	for_each_online_cpu(cpu)
-		bnx2fc_percpu_thread_create(cpu);
-
-	rc = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,
-						  "scsi/bnx2fc:online",
-						  bnx2fc_cpu_online, NULL);
+	rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "scsi/bnx2fc:online",
+			       bnx2fc_cpu_online, bnx2fc_cpu_offline);
 	if (rc < 0)
-		goto stop_threads;
+		goto stop_thread;
 	bnx2fc_online_state = rc;
 
-	cpuhp_setup_state_nocalls_cpuslocked(CPUHP_SCSI_BNX2FC_DEAD,
-					     "scsi/bnx2fc:dead",
-					     NULL, bnx2fc_cpu_dead);
-	put_online_cpus();
-
 	cnic_register_driver(CNIC_ULP_FCOE, &bnx2fc_cnic_cb);
-
 	return 0;
 
-stop_threads:
-	for_each_online_cpu(cpu)
-		bnx2fc_percpu_thread_destroy(cpu);
-	put_online_cpus();
+stop_thread:
 	kthread_stop(l2_thread);
 free_wq:
 	destroy_workqueue(bnx2fc_wq);
@@ -2804,7 +2775,6 @@ static void __exit bnx2fc_mod_exit(void)
 	struct fcoe_percpu_s *bg;
 	struct task_struct *l2_thread;
 	struct sk_buff *skb;
-	unsigned int cpu = 0;
 
 	/*
 	 * NOTE: Since cnic calls register_driver routine rtnl_lock,
@@ -2845,16 +2815,7 @@ static void __exit bnx2fc_mod_exit(void)
 	if (l2_thread)
 		kthread_stop(l2_thread);
 
-	get_online_cpus();
-	/* Destroy per cpu threads */
-	for_each_online_cpu(cpu) {
-		bnx2fc_percpu_thread_destroy(cpu);
-	}
-
-	cpuhp_remove_state_nocalls_cpuslocked(bnx2fc_online_state);
-	cpuhp_remove_state_nocalls_cpuslocked(CPUHP_SCSI_BNX2FC_DEAD);
-
-	put_online_cpus();
+	cpuhp_remove_state(bnx2fc_online_state);
 
 	destroy_workqueue(bnx2fc_wq);
 	/*
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -39,7 +39,6 @@ enum cpuhp_state {
 	CPUHP_PCI_XGENE_DEAD,
 	CPUHP_IOMMU_INTEL_DEAD,
 	CPUHP_LUSTRE_CFS_DEAD,
-	CPUHP_SCSI_BNX2FC_DEAD,
 	CPUHP_SCSI_BNX2I_DEAD,
 	CPUHP_WORKQUEUE_PREP,
 	CPUHP_POWER_NUMA_PREPARE,