IB/ehca: Fix sync between completion handler and destroy cq
This patch fixes two issues reported by Roland Dreier and Christoph Hellwig:
- Mismatched sync/locking between completion handler and destroy cq We
introduced a counter nr_events per cq to track number of irq events
seen. This counter is incremented when an event queue entry is seen
and decremented after completion handler has been called regardless
if scaling code is active or not. Note that nr_callbacks tracks
number of events assigned to a cpu and both counters can potentially
diverge.
The sync between running completion handler and destroy cq is done
by using the global spin lock ehca_cq_idr_lock.
- Replace yield by wait_event on the counter above to become zero.
Signed-off-by: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
index 3ec53c6..20f36bf 100644
--- a/drivers/infiniband/hw/ehca/ehca_irq.c
+++ b/drivers/infiniband/hw/ehca/ehca_irq.c
@@ -404,10 +404,11 @@
u32 token;
unsigned long flags;
struct ehca_cq *cq;
+
eqe_value = eqe->entry;
ehca_dbg(&shca->ib_device, "eqe_value=%lx", eqe_value);
if (EHCA_BMASK_GET(EQE_COMPLETION_EVENT, eqe_value)) {
- ehca_dbg(&shca->ib_device, "... completion event");
+ ehca_dbg(&shca->ib_device, "Got completion event");
token = EHCA_BMASK_GET(EQE_CQ_TOKEN, eqe_value);
spin_lock_irqsave(&ehca_cq_idr_lock, flags);
cq = idr_find(&ehca_cq_idr, token);
@@ -419,16 +420,20 @@
return;
}
reset_eq_pending(cq);
- if (ehca_scaling_code) {
+ cq->nr_events++;
+ spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+ if (ehca_scaling_code)
queue_comp_task(cq);
- spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
- } else {
- spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+ else {
comp_event_callback(cq);
+ spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+ cq->nr_events--;
+ if (!cq->nr_events)
+ wake_up(&cq->wait_completion);
+ spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
}
} else {
- ehca_dbg(&shca->ib_device,
- "Got non completion event");
+ ehca_dbg(&shca->ib_device, "Got non completion event");
parse_identifier(shca, eqe_value);
}
}
@@ -478,6 +483,7 @@
"token=%x", token);
continue;
}
+ eqe_cache[eqe_cnt].cq->nr_events++;
spin_unlock(&ehca_cq_idr_lock);
} else
eqe_cache[eqe_cnt].cq = NULL;
@@ -504,12 +510,18 @@
/* call completion handler for cached eqes */
for (i = 0; i < eqe_cnt; i++)
if (eq->eqe_cache[i].cq) {
- if (ehca_scaling_code) {
- spin_lock(&ehca_cq_idr_lock);
+ if (ehca_scaling_code)
queue_comp_task(eq->eqe_cache[i].cq);
- spin_unlock(&ehca_cq_idr_lock);
- } else
- comp_event_callback(eq->eqe_cache[i].cq);
+ else {
+ struct ehca_cq *cq = eq->eqe_cache[i].cq;
+ comp_event_callback(cq);
+ spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+ cq->nr_events--;
+ if (!cq->nr_events)
+ wake_up(&cq->wait_completion);
+ spin_unlock_irqrestore(&ehca_cq_idr_lock,
+ flags);
+ }
} else {
ehca_dbg(&shca->ib_device, "Got non completion event");
parse_identifier(shca, eq->eqe_cache[i].eqe->entry);
@@ -523,7 +535,6 @@
if (!eqe)
break;
process_eqe(shca, eqe);
- eqe_cnt++;
} while (1);
unlock_irq_spinlock:
@@ -567,8 +578,7 @@
list_add_tail(&__cq->entry, &cct->cq_list);
cct->cq_jobs++;
wake_up(&cct->wait_queue);
- }
- else
+ } else
__cq->nr_callbacks++;
spin_unlock(&__cq->task_lock);
@@ -577,18 +587,21 @@
static void queue_comp_task(struct ehca_cq *__cq)
{
- int cpu;
int cpu_id;
struct ehca_cpu_comp_task *cct;
+ int cq_jobs;
+ unsigned long flags;
- 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) {
+ spin_lock_irqsave(&cct->task_lock, flags);
+ cq_jobs = cct->cq_jobs;
+ spin_unlock_irqrestore(&cct->task_lock, flags);
+ if (cq_jobs > 0) {
cpu_id = find_next_online_cpu(pool);
cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu_id);
BUG_ON(!cct);
@@ -608,11 +621,17 @@
cq = list_entry(cct->cq_list.next, struct ehca_cq, entry);
spin_unlock_irqrestore(&cct->task_lock, flags);
comp_event_callback(cq);
- spin_lock_irqsave(&cct->task_lock, flags);
+ spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+ cq->nr_events--;
+ if (!cq->nr_events)
+ wake_up(&cq->wait_completion);
+ spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+
+ spin_lock_irqsave(&cct->task_lock, flags);
spin_lock(&cq->task_lock);
cq->nr_callbacks--;
- if (cq->nr_callbacks == 0) {
+ if (!cq->nr_callbacks) {
list_del_init(cct->cq_list.next);
cct->cq_jobs--;
}