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Message-Id: <200702151707.31021.hnguyen@linux.vnet.ibm.com>
Date: Thu, 15 Feb 2007 17:07:30 +0100
From: Hoang-Nam Nguyen <hnguyen@...ux.vnet.ibm.com>
To: Roland Dreier <rdreier@...co.com>, linux-kernel@...r.kernel.org,
linuxppc-dev@...abs.org, openib-general@...nib.org,
hch@...radead.org, bos@...hscale.com
Cc: raisch@...ibm.com, heiko.carstens@...ibm.com
Subject: [PATCH 2.6.21-rc1 2/5] ehca: fix race condition/locking issues in scaling code
fix a race condition in find_next_cpu_online() and some
other locking issues in scaling code
Signed-off-by: Hoang-Nam Nguyen <hnguyen@...ibm.com>
---
ehca_irq.c | 68 +++++++++++++++++++++++++++++--------------------------------
1 files changed, 33 insertions(+), 35 deletions(-)
diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
index b923b5d..9679b07 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 ehc
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_
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 ehc
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;
}
-
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