[PATCH v3 18/18] ibmvfc: drop host lock when completing commands in CRQ

Tyrel Datwyler
2020-12-03T02:10:49Z

The legacy CRQ holds the host lock the even while completing commands.
This presents a problem when in legacy single queue mode and
nr_hw_queues is greater than one since calling scsi_done() introduces
the potential for deadlock.

If nr_hw_queues is greater than one drop the hostlock in the legacy CRQ
path when completing a command.

Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
---
drivers/scsi/ibmvscsi/ibmvfc.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index e499599662ec..e2200bdff2be 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -2969,6 +2969,7 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost)
{
long rc;
struct ibmvfc_event *evt = (struct ibmvfc_event *)be64_to_cpu(crq->ioba);
+ unsigned long flags;

switch (crq->valid) {
case IBMVFC_CRQ_INIT_RSP:
@@ -3039,7 +3040,12 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost)
del_timer(&evt->timer);
list_del(&evt->queue);
ibmvfc_trc_end(evt);
- evt->done(evt);
+ if (nr_scsi_hw_queues > 1) {
+ spin_unlock_irqrestore(vhost->host->host_lock, flags);
+ evt->done(evt);
+ spin_lock_irqsave(vhost->host->host_lock, flags);
+ } else
+ evt->done(evt);
}

/**
--
2.27.0