From: Dave Marquardt <[email protected]>
Add ibmvfc_interrupt_async_subq(), an IRQ handler dedicated to
asynchronous sub-CRQ events from the adapter. The handler disables
the sub-CRQ IRQ and then calls ibmvfc_drain_async_subq() to consume
all pending entries before re-enabling interrupts.
ibmvfc_drain_async_subq() holds both the host lock and the per-queue
q_lock while processing. It loops over available CRQ entries via
ibmvfc_next_scrq(), dispatching each to ibmvfc_handle_async() with
the async flag set, then clears the valid bit and issues a write
barrier. After draining, it re-enables the sub-CRQ IRQ and performs
one final check for a newly arrived entry to close the IRQ-enable
race; if one is found it is processed before exiting the loop.
---
drivers/scsi/ibmvscsi/ibmvfc-core.c | 46 +++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/drivers/scsi/ibmvscsi/ibmvfc-core.c
b/drivers/scsi/ibmvscsi/ibmvfc-core.c
index 37ee8f00322a..23c1a4cb40d9 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc-core.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc-core.c
@@ -4337,6 +4337,52 @@ static struct ibmvfc_crq *ibmvfc_next_scrq(struct
ibmvfc_queue *scrq)
return crq;
}
+static void ibmvfc_drain_async_subq(struct ibmvfc_queue *scrq)
+{
+ struct ibmvfc_host *vhost = scrq->vhost;
+ struct ibmvfc_crq *crq;
+ unsigned long flags;
+ int done = 0;
+
+ spin_lock_irqsave(vhost->host->host_lock, flags);
+ spin_lock(scrq->q_lock);
+ while (!done) {
+ while ((crq = ibmvfc_next_scrq(scrq)) != NULL) {
+ ibmvfc_handle_async(crq, scrq->vhost, true);
+ crq->valid = 0;
+ wmb(); /* complete write */
+ }
+
+ ibmvfc_toggle_scrq_irq(scrq, 1);
+ crq = ibmvfc_next_scrq(scrq);
+ if (crq != NULL) {
+ ibmvfc_toggle_scrq_irq(scrq, 0);
+ ibmvfc_handle_async(crq, scrq->vhost, true);
+ crq->valid = 0;
+ wmb(); /* complete write */
+ } else
+ done = 1;
+ }
+ spin_unlock(scrq->q_lock);
+ spin_unlock_irqrestore(vhost->host->host_lock, flags);
+}
+
+/**
+ * ibmvfc_interrupt_async_subq - Handle an async event from the adapter
+ * @irq: interrupt request
+ * @scrq_instance: async subq
+ *
+ **/
+static irqreturn_t ibmvfc_interrupt_async_subq(int irq, void *scrq_instance)
+{
+ struct ibmvfc_queue *scrq = (struct ibmvfc_queue *)scrq_instance;
+
+ ibmvfc_toggle_scrq_irq(scrq, 0);
+ ibmvfc_drain_async_subq(scrq);
+
+ return IRQ_HANDLED;
+}
+
static void ibmvfc_drain_sub_crq(struct ibmvfc_queue *scrq)
{
struct ibmvfc_crq *crq;
--
2.55.0
