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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 <hnguyen@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Hoang-Nam Nguyen 2007-02-15 17:07:30 +01:00 committed by Roland Dreier
parent 78d8d5f9ef
commit 8b16cef3df
1 changed files with 33 additions and 35 deletions
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68
drivers/infiniband/hw/ehca/ehca_irq.c
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@ -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;
}