From 8b16cef3df871b005f3a97e273b5b135ebfb3769 Mon Sep 17 00:00:00 2001 From: Hoang-Nam Nguyen Date: Thu, 15 Feb 2007 17:07:30 +0100 Subject: [PATCH] IB/ehca: Fix race condition/locking issues in scaling code Fix a race condition in find_next_cpu_online() and some other locking issues in ehca scaling code. Signed-off-by: Hoang-Nam Nguyen Signed-off-by: Roland Dreier --- drivers/infiniband/hw/ehca/ehca_irq.c | 68 +++++++++++++-------------- 1 file changed, 33 insertions(+), 35 deletions(-) diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c index b923b5d5de68..9679b072ad01 100644 --- a/drivers/infiniband/hw/ehca/ehca_irq.c +++ b/drivers/infiniband/hw/ehca/ehca_irq.c @@ -544,28 +544,30 @@ void ehca_tasklet_eq(unsigned long data) static inline int find_next_online_cpu(struct ehca_comp_pool* pool) { - unsigned long flags_last_cpu; + int cpu; + unsigned long flags; + WARN_ON_ONCE(!in_interrupt()); if (ehca_debug_level) ehca_dmp(&cpu_online_map, sizeof(cpumask_t), ""); - spin_lock_irqsave(&pool->last_cpu_lock, flags_last_cpu); - pool->last_cpu = next_cpu(pool->last_cpu, cpu_online_map); - if (pool->last_cpu == NR_CPUS) - pool->last_cpu = first_cpu(cpu_online_map); - spin_unlock_irqrestore(&pool->last_cpu_lock, flags_last_cpu); + spin_lock_irqsave(&pool->last_cpu_lock, flags); + cpu = next_cpu(pool->last_cpu, cpu_online_map); + if (cpu == NR_CPUS) + cpu = first_cpu(cpu_online_map); + pool->last_cpu = cpu; + spin_unlock_irqrestore(&pool->last_cpu_lock, flags); - return pool->last_cpu; + return cpu; } static void __queue_comp_task(struct ehca_cq *__cq, struct ehca_cpu_comp_task *cct) { - unsigned long flags_cct; - unsigned long flags_cq; + unsigned long flags; - spin_lock_irqsave(&cct->task_lock, flags_cct); - spin_lock_irqsave(&__cq->task_lock, flags_cq); + spin_lock_irqsave(&cct->task_lock, flags); + spin_lock(&__cq->task_lock); if (__cq->nr_callbacks == 0) { __cq->nr_callbacks++; @@ -576,8 +578,8 @@ static void __queue_comp_task(struct ehca_cq *__cq, else __cq->nr_callbacks++; - spin_unlock_irqrestore(&__cq->task_lock, flags_cq); - spin_unlock_irqrestore(&cct->task_lock, flags_cct); + spin_unlock(&__cq->task_lock); + spin_unlock_irqrestore(&cct->task_lock, flags); } static void queue_comp_task(struct ehca_cq *__cq) @@ -588,69 +590,69 @@ static void queue_comp_task(struct ehca_cq *__cq) cpu = get_cpu(); cpu_id = find_next_online_cpu(pool); - BUG_ON(!cpu_online(cpu_id)); cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu_id); + BUG_ON(!cct); if (cct->cq_jobs > 0) { cpu_id = find_next_online_cpu(pool); cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu_id); + BUG_ON(!cct); } __queue_comp_task(__cq, cct); - - put_cpu(); - - return; } static void run_comp_task(struct ehca_cpu_comp_task* cct) { struct ehca_cq *cq; - unsigned long flags_cct; - unsigned long flags_cq; + unsigned long flags; - spin_lock_irqsave(&cct->task_lock, flags_cct); + 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_cct); + spin_unlock_irqrestore(&cct->task_lock, flags); comp_event_callback(cq); - spin_lock_irqsave(&cct->task_lock, flags_cct); + spin_lock_irqsave(&cct->task_lock, flags); - spin_lock_irqsave(&cq->task_lock, flags_cq); + spin_lock(&cq->task_lock); cq->nr_callbacks--; if (cq->nr_callbacks == 0) { list_del_init(cct->cq_list.next); cct->cq_jobs--; } - spin_unlock_irqrestore(&cq->task_lock, flags_cq); - + spin_unlock(&cq->task_lock); } - spin_unlock_irqrestore(&cct->task_lock, flags_cct); - - return; + spin_unlock_irqrestore(&cct->task_lock, flags); } static int comp_task(void *__cct) { 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); - if (list_empty(&cct->cq_list)) + 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); - if (!list_empty(&cct->cq_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); set_current_state(TASK_INTERRUPTIBLE); @@ -693,8 +695,6 @@ static void destroy_comp_task(struct ehca_comp_pool *pool, if (task) kthread_stop(task); - - return; } static void take_over_work(struct ehca_comp_pool *pool, @@ -815,6 +815,4 @@ void ehca_destroy_comp_pool(void) free_percpu(pool->cpu_comp_tasks); kfree(pool); #endif - - return; } -- 2.20.1