infiniband: Ehca: Use hotplug thread infrastructure

Get rid of the hotplug notifiers and use the generic hotplug thread
infrastructure.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20120716103948.775527032@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
index 5358900..4eeac40 100644 (file)
--- a/drivers/infiniband/hw/ehca/ehca_irq.c
+++ b/drivers/infiniband/hw/ehca/ehca_irq.c
@@ -42,6 +42,7 @@
  */
 
 #include <linux/slab.h>
+#include <linux/smpboot.h>
 
 #include "ehca_classes.h"
 #include "ehca_irq.h"
@@ -652,7 +653,7 @@ void ehca_tasklet_eq(unsigned long data)
        ehca_process_eq((struct ehca_shca*)data, 1);
 }
 
-static inline int find_next_online_cpu(struct ehca_comp_pool *pool)
+static int find_next_online_cpu(struct ehca_comp_pool *pool)
 {
        int cpu;
        unsigned long flags;
@@ -662,17 +663,20 @@ static inline int find_next_online_cpu(struct ehca_comp_pool *pool)
                ehca_dmp(cpu_online_mask, cpumask_size(), "");
 
        spin_lock_irqsave(&pool->last_cpu_lock, flags);
-       cpu = cpumask_next(pool->last_cpu, cpu_online_mask);
-       if (cpu >= nr_cpu_ids)
-               cpu = cpumask_first(cpu_online_mask);
-       pool->last_cpu = cpu;
+       do {
+               cpu = cpumask_next(pool->last_cpu, cpu_online_mask);
+               if (cpu >= nr_cpu_ids)
+                       cpu = cpumask_first(cpu_online_mask);
+               pool->last_cpu = cpu;
+       } while (!per_cpu_ptr(pool->cpu_comp_tasks, cpu)->active)
        spin_unlock_irqrestore(&pool->last_cpu_lock, flags);
 
        return cpu;
 }
 
 static void __queue_comp_task(struct ehca_cq *__cq,
-                             struct ehca_cpu_comp_task *cct)
+                             struct ehca_cpu_comp_task *cct,
+                             struct task_struct *thread)
 {
        unsigned long flags;
 
@@ -683,7 +687,7 @@ static void __queue_comp_task(struct ehca_cq *__cq,
                __cq->nr_callbacks++;
                list_add_tail(&__cq->entry, &cct->cq_list);
                cct->cq_jobs++;
-               wake_up(&cct->wait_queue);
+               wake_up_process(thread);
        } else
                __cq->nr_callbacks++;
 
@@ -695,6 +699,7 @@ static void queue_comp_task(struct ehca_cq *__cq)
 {
        int cpu_id;
        struct ehca_cpu_comp_task *cct;
+       struct task_struct *thread;
        int cq_jobs;
        unsigned long flags;
 
@@ -702,7 +707,8 @@ static void queue_comp_task(struct ehca_cq *__cq)
        BUG_ON(!cpu_online(cpu_id));
 
        cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu_id);
-       BUG_ON(!cct);
+       thread = per_cpu_ptr(pool->cpu_comp_threads, cpu_id);
+       BUG_ON(!cct || !thread);
 
        spin_lock_irqsave(&cct->task_lock, flags);
        cq_jobs = cct->cq_jobs;
@@ -710,28 +716,25 @@ static void queue_comp_task(struct ehca_cq *__cq)
        if (cq_jobs > 0) {
                cpu_id = find_next_online_cpu(pool);
                cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu_id);
-               BUG_ON(!cct);
+               thread = per_cpu_ptr(pool->cpu_comp_threads, cpu_id);
+               BUG_ON(!cct || !thread);
        }
-
-       __queue_comp_task(__cq, cct);
+       __queue_comp_task(__cq, cct, thread);
 }
 
 static void run_comp_task(struct ehca_cpu_comp_task *cct)
 {
        struct ehca_cq *cq;
-       unsigned long flags;
-
-       spin_lock_irqsave(&cct->task_lock, flags);
 
        while (!list_empty(&cct->cq_list)) {
                cq = list_entry(cct->cq_list.next, struct ehca_cq, entry);
-               spin_unlock_irqrestore(&cct->task_lock, flags);
+               spin_unlock_irq(&cct->task_lock);
 
                comp_event_callback(cq);
                if (atomic_dec_and_test(&cq->nr_events))
                        wake_up(&cq->wait_completion);
 
-               spin_lock_irqsave(&cct->task_lock, flags);
+               spin_lock_irq(&cct->task_lock);
                spin_lock(&cq->task_lock);
                cq->nr_callbacks--;
                if (!cq->nr_callbacks) {
@@ -740,159 +743,76 @@ static void run_comp_task(struct ehca_cpu_comp_task *cct)
                }
                spin_unlock(&cq->task_lock);
        }
-
-       spin_unlock_irqrestore(&cct->task_lock, flags);
 }
 
-static int comp_task(void *__cct)
+static void comp_task_park(unsigned int cpu)
 {
-       struct ehca_cpu_comp_task *cct = __cct;
-       int cql_empty;
-       DECLARE_WAITQUEUE(wait, current);
-
-       set_current_state(TASK_INTERRUPTIBLE);
-       while (!kthread_should_stop()) {
-               add_wait_queue(&cct->wait_queue, &wait);
-
-               spin_lock_irq(&cct->task_lock);
-               cql_empty = list_empty(&cct->cq_list);
-               spin_unlock_irq(&cct->task_lock);
-               if (cql_empty)
-                       schedule();
-               else
-                       __set_current_state(TASK_RUNNING);
-
-               remove_wait_queue(&cct->wait_queue, &wait);
+       struct ehca_cpu_comp_task *cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
+       struct ehca_cpu_comp_task *target;
+       struct task_struct *thread;
+       struct ehca_cq *cq, *tmp;
+       LIST_HEAD(list);
 
-               spin_lock_irq(&cct->task_lock);
-               cql_empty = list_empty(&cct->cq_list);
-               spin_unlock_irq(&cct->task_lock);
-               if (!cql_empty)
-                       run_comp_task(__cct);
+       spin_lock_irq(&cct->task_lock);
+       cct->cq_jobs = 0;
+       cct->active = 0;
+       list_splice_init(&cct->cq_list, &list);
+       spin_unlock_irq(&cct->task_lock);
 
-               set_current_state(TASK_INTERRUPTIBLE);
+       cpu = find_next_online_cpu(pool);
+       target = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
+       thread = per_cpu_ptr(pool->cpu_comp_threads, cpu);
+       spin_lock_irq(&target->task_lock);
+       list_for_each_entry_safe(cq, tmp, &list, entry) {
+               list_del(&cq->entry);
+               __queue_comp_task(cq, target, thread);
        }
-       __set_current_state(TASK_RUNNING);
-
-       return 0;
-}
-
-static struct task_struct *create_comp_task(struct ehca_comp_pool *pool,
-                                           int cpu)
-{
-       struct ehca_cpu_comp_task *cct;
-
-       cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
-       spin_lock_init(&cct->task_lock);
-       INIT_LIST_HEAD(&cct->cq_list);
-       init_waitqueue_head(&cct->wait_queue);
-       cct->task = kthread_create_on_node(comp_task, cct, cpu_to_node(cpu),
-                                          "ehca_comp/%d", cpu);
-
-       return cct->task;
+       spin_unlock_irq(&target->task_lock);
 }
 
-static void destroy_comp_task(struct ehca_comp_pool *pool,
-                             int cpu)
+static void comp_task_stop(unsigned int cpu, bool online)
 {
-       struct ehca_cpu_comp_task *cct;
-       struct task_struct *task;
-       unsigned long flags_cct;
-
-       cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
-
-       spin_lock_irqsave(&cct->task_lock, flags_cct);
+       struct ehca_cpu_comp_task *cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
 
-       task = cct->task;
-       cct->task = NULL;
+       spin_lock_irq(&cct->task_lock);
        cct->cq_jobs = 0;
-
-       spin_unlock_irqrestore(&cct->task_lock, flags_cct);
-
-       if (task)
-               kthread_stop(task);
+       cct->active = 0;
+       WARN_ON(!list_empty(&cct->cq_list));
+       spin_unlock_irq(&cct->task_lock);
 }
 
-static void __cpuinit take_over_work(struct ehca_comp_pool *pool, int cpu)
+static int comp_task_should_run(unsigned int cpu)
 {
        struct ehca_cpu_comp_task *cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
-       LIST_HEAD(list);
-       struct ehca_cq *cq;
-       unsigned long flags_cct;
-
-       spin_lock_irqsave(&cct->task_lock, flags_cct);
-
-       list_splice_init(&cct->cq_list, &list);
-
-       while (!list_empty(&list)) {
-               cq = list_entry(cct->cq_list.next, struct ehca_cq, entry);
-
-               list_del(&cq->entry);
-               __queue_comp_task(cq, this_cpu_ptr(pool->cpu_comp_tasks));
-       }
-
-       spin_unlock_irqrestore(&cct->task_lock, flags_cct);
 
+       return cct->cq_jobs;
 }
 
-static int __cpuinit comp_pool_callback(struct notifier_block *nfb,
-                                       unsigned long action,
-                                       void *hcpu)
+static int comp_task(unsigned int cpu)
 {
-       unsigned int cpu = (unsigned long)hcpu;
-       struct ehca_cpu_comp_task *cct;
+       struct ehca_cpu_comp_task *cct = this_cpu_ptr(pool->cpu_comp_tasks);
+       int cql_empty;
 
-       switch (action) {
-       case CPU_UP_PREPARE:
-       case CPU_UP_PREPARE_FROZEN:
-               ehca_gen_dbg("CPU: %x (CPU_PREPARE)", cpu);
-               if (!create_comp_task(pool, cpu)) {
-                       ehca_gen_err("Can't create comp_task for cpu: %x", cpu);
-                       return notifier_from_errno(-ENOMEM);
-               }
-               break;
-       case CPU_UP_CANCELED:
-       case CPU_UP_CANCELED_FROZEN:
-               ehca_gen_dbg("CPU: %x (CPU_CANCELED)", cpu);
-               cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
-               kthread_bind(cct->task, cpumask_any(cpu_online_mask));
-               destroy_comp_task(pool, cpu);
-               break;
-       case CPU_ONLINE:
-       case CPU_ONLINE_FROZEN:
-               ehca_gen_dbg("CPU: %x (CPU_ONLINE)", cpu);
-               cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
-               kthread_bind(cct->task, cpu);
-               wake_up_process(cct->task);
-               break;
-       case CPU_DOWN_PREPARE:
-       case CPU_DOWN_PREPARE_FROZEN:
-               ehca_gen_dbg("CPU: %x (CPU_DOWN_PREPARE)", cpu);
-               break;
-       case CPU_DOWN_FAILED:
-       case CPU_DOWN_FAILED_FROZEN:
-               ehca_gen_dbg("CPU: %x (CPU_DOWN_FAILED)", cpu);
-               break;
-       case CPU_DEAD:
-       case CPU_DEAD_FROZEN:
-               ehca_gen_dbg("CPU: %x (CPU_DEAD)", cpu);
-               destroy_comp_task(pool, cpu);
-               take_over_work(pool, cpu);
-               break;
+       spin_lock_irq(&cct->task_lock);
+       cql_empty = list_empty(&cct->cq_list);
+       if (!cql_empty) {
+               __set_current_state(TASK_RUNNING);
+               run_comp_task(cct);
        }
-
-       return NOTIFY_OK;
+       spin_unlock_irq(&cct->task_lock);
 }
 
-static struct notifier_block comp_pool_callback_nb __cpuinitdata = {
-       .notifier_call  = comp_pool_callback,
-       .priority       = 0,
+static struct smp_hotplug_thread comp_pool_threads = {
+       .thread_should_run      = comp_task_should_run,
+       .thread_fn              = comp_task,
+       .thread_comm            = "ehca_comp/%u",
+       .cleanup                = comp_task_stop,
+       .park                   = comp_task_park,
 };
 
 int ehca_create_comp_pool(void)
 {
-       int cpu;
-       struct task_struct *task;
+       int cpu, ret = -ENOMEM;
 
        if (!ehca_scaling_code)
                return 0;
@@ -905,38 +825,46 @@ int ehca_create_comp_pool(void)
        pool->last_cpu = cpumask_any(cpu_online_mask);
 
        pool->cpu_comp_tasks = alloc_percpu(struct ehca_cpu_comp_task);
-       if (pool->cpu_comp_tasks == NULL) {
-               kfree(pool);
-               return -EINVAL;
-       }
+       if (!pool->cpu_comp_tasks)
+               goto out_pool;
 
-       for_each_online_cpu(cpu) {
-               task = create_comp_task(pool, cpu);
-               if (task) {
-                       kthread_bind(task, cpu);
-                       wake_up_process(task);
-               }
+       pool->cpu_comp_threads = alloc_percpu(struct task_struct *);
+       if (!pool->cpu_comp_threads)
+               goto out_tasks;
+
+       for_each_present_cpu(cpu) {
+               struct ehca_cpu_comp_task *cct;
+
+               cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
+               spin_lock_init(&cct->task_lock);
+               INIT_LIST_HEAD(&cct->cq_list);
        }
 
-       register_hotcpu_notifier(&comp_pool_callback_nb);
+       comp_pool_threads.store = pool->cpu_comp_threads;
+       ret = smpboot_register_percpu_thread(&comp_pool_threads);
+       if (ret)
+               goto out_threads;
 
-       printk(KERN_INFO "eHCA scaling code enabled\n");
+       pr_info("eHCA scaling code enabled\n");
+       return ret;
 
-       return 0;
+out_threads:
+       free_percpu(pool->cpu_comp_threads);
+out_tasks:
+       free_percpu(pool->cpu_comp_tasks);
+out_pool:
+       kfree(pool);
+       return ret;
 }
 
 void ehca_destroy_comp_pool(void)
 {
-       int i;
-
        if (!ehca_scaling_code)
                return;
 
-       unregister_hotcpu_notifier(&comp_pool_callback_nb);
-
-       for_each_online_cpu(i)
-               destroy_comp_task(pool, i);
+       smpboot_unregister_percpu_thread(&comp_pool_threads);
 
+       free_percpu(pool->cpu_comp_threads);
        free_percpu(pool->cpu_comp_tasks);
        kfree(pool);
 }

diff --git a/drivers/infiniband/hw/ehca/ehca_irq.h b/drivers/infiniband/hw/ehca/ehca_irq.h
index 3346cb0..5370199 100644 (file)
--- a/drivers/infiniband/hw/ehca/ehca_irq.h
+++ b/drivers/infiniband/hw/ehca/ehca_irq.h
@@ -58,15 +58,15 @@ void ehca_tasklet_eq(unsigned long data);
 void ehca_process_eq(struct ehca_shca *shca, int is_irq);
 
 struct ehca_cpu_comp_task {
-       wait_queue_head_t wait_queue;
        struct list_head cq_list;
-       struct task_struct *task;
        spinlock_t task_lock;
        int cq_jobs;
+       int active;
 };
 
 struct ehca_comp_pool {
-       struct ehca_cpu_comp_task *cpu_comp_tasks;
+       struct ehca_cpu_comp_task __percpu *cpu_comp_tasks;
+       struct task_struct * __percpu *cpu_comp_threads;
        int last_cpu;
        spinlock_t last_cpu_lock;
 };