RDMA/usnic: Lock VF with mutex instead of spinlock

Usnic VF doesn't need lock in atomic context to create QPs, so it is safe
to use mutex instead of spinlock. Such change fixes the following smatch
error.

Smatch static checker warning:

   lib/kobject.c:289 kobject_set_name_vargs()
    warn: sleeping in atomic context

Fixes: 514aee6 ("RDMA: Globally allocate and release QP memory")
Link: https://lore.kernel.org/r/2a0e295786c127e518ebee8bb7cafcb819a625f6.1631520231.git.leonro@nvidia.com
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/usnic/usnic_ib.h

@@ -90,7 +90,7 @@ struct usnic_ib_dev {
 
 struct usnic_ib_vf {
 	struct usnic_ib_dev		*pf;
-	spinlock_t			lock;
+	struct mutex			lock;
 	struct usnic_vnic		*vnic;
 	unsigned int			qp_grp_ref_cnt;
 	struct usnic_ib_pd		*pd;

drivers/infiniband/hw/usnic/usnic_ib_main.c

@@ -572,7 +572,7 @@ static int usnic_ib_pci_probe(struct pci_dev *pdev,
 	}
 
 	vf->pf = pf;
-	spin_lock_init(&vf->lock);
+	mutex_init(&vf->lock);
 	mutex_lock(&pf->usdev_lock);
 	list_add_tail(&vf->link, &pf->vf_dev_list);
 	/*

drivers/infiniband/hw/usnic/usnic_ib_verbs.c

@@ -196,7 +196,7 @@ find_free_vf_and_create_qp_grp(struct ib_qp *qp,
 		for (i = 0; dev_list[i]; i++) {
 			dev = dev_list[i];
 			vf = dev_get_drvdata(dev);
-			spin_lock(&vf->lock);
+			mutex_lock(&vf->lock);
 			vnic = vf->vnic;
 			if (!usnic_vnic_check_room(vnic, res_spec)) {
 				usnic_dbg("Found used vnic %s from %s\n",
@@ -208,10 +208,10 @@ find_free_vf_and_create_qp_grp(struct ib_qp *qp,
 							     vf, pd, res_spec,
 							     trans_spec);
 
-				spin_unlock(&vf->lock);
+				mutex_unlock(&vf->lock);
 				goto qp_grp_check;
 			}
-			spin_unlock(&vf->lock);
+			mutex_unlock(&vf->lock);
 
 		}
 		usnic_uiom_free_dev_list(dev_list);
@@ -220,18 +220,18 @@ find_free_vf_and_create_qp_grp(struct ib_qp *qp,
 
 	/* Try to find resources on an unused vf */
 	list_for_each_entry(vf, &us_ibdev->vf_dev_list, link) {
-		spin_lock(&vf->lock);
+		mutex_lock(&vf->lock);
 		vnic = vf->vnic;
 		if (vf->qp_grp_ref_cnt == 0 &&
 		    usnic_vnic_check_room(vnic, res_spec) == 0) {
 			ret = usnic_ib_qp_grp_create(qp_grp, us_ibdev->ufdev,
 						     vf, pd, res_spec,
 						     trans_spec);
 
-			spin_unlock(&vf->lock);
+			mutex_unlock(&vf->lock);
 			goto qp_grp_check;
 		}
-		spin_unlock(&vf->lock);
+		mutex_unlock(&vf->lock);
 	}
 
 	usnic_info("No free qp grp found on %s\n",
@@ -253,9 +253,9 @@ static void qp_grp_destroy(struct usnic_ib_qp_grp *qp_grp)
 
 	WARN_ON(qp_grp->state != IB_QPS_RESET);
 
-	spin_lock(&vf->lock);
+	mutex_lock(&vf->lock);
 	usnic_ib_qp_grp_destroy(qp_grp);
-	spin_unlock(&vf->lock);
+	mutex_unlock(&vf->lock);
 }
 
 static int create_qp_validate_user_data(struct usnic_ib_create_qp_cmd cmd)