iw_cxgb4: Fix possible circular dependency locking warning

Locking sequence of iw_cxgb4 and RoCE drivers in ib_register_device() is
slightly different and this leads to possible circular dependency locking
warning when both the devices are brought up.

Here is the locking sequence upto ib_register_device():
iw_cxgb4: rtnl_mutex(net stack) --> uld_mutex --> device_mutex
RoCE drivers: device_mutex --> rtnl_mutex

Here is the possibility of cross locking:

	CPU #0 (iw_cxgb4) 		     CPU #1 (RoCE drivers)

-> on interface up cxgb4_up()
executed with rtnl_mutex held
-> hold uld_mutex and try
registering ib device
					-> In ib_register_device() hold
					   device_mutex
-> hold device mutex in
ib_register_device
					-> try acquiring rtnl_mutex in
					   ib_enum_roce_netdev()

Current patch schedules the ib_register_device() functionality of
iw_cxgb4 to a workqueue to prevent the possible cross-locking.
Also rename the labels in c4iw_reister_device().

Signed-off-by: Potnuri Bharat Teja <bharat@chelsio.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
index 8d525825d50c..470f97a79ebb 100644
--- a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
+++ b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
@@ -322,6 +322,13 @@ struct c4iw_dev {
 	wait_queue_head_t wait;
 };
 
+struct uld_ctx {
+	struct list_head entry;
+	struct cxgb4_lld_info lldi;
+	struct c4iw_dev *dev;
+	struct work_struct reg_work;
+};
+
 static inline struct c4iw_dev *to_c4iw_dev(struct ib_device *ibdev)
 {
 	return container_of(ibdev, struct c4iw_dev, ibdev);
@@ -988,7 +995,7 @@ void c4iw_rqtpool_destroy(struct c4iw_rdev *rdev);
 void c4iw_ocqp_pool_destroy(struct c4iw_rdev *rdev);
 void c4iw_destroy_resource(struct c4iw_resource *rscp);
 int c4iw_destroy_ctrl_qp(struct c4iw_rdev *rdev);
-int c4iw_register_device(struct c4iw_dev *dev);
+void c4iw_register_device(struct work_struct *work);
 void c4iw_unregister_device(struct c4iw_dev *dev);
 int __init c4iw_cm_init(void);
 void c4iw_cm_term(void);
@@ -1014,6 +1021,7 @@ struct ib_mr *c4iw_alloc_mr(struct ib_pd *pd,
 int c4iw_map_mr_sg(struct ib_mr *ibmr, struct scatterlist *sg, int sg_nents,
 		   unsigned int *sg_offset);
 int c4iw_dealloc_mw(struct ib_mw *mw);
+void c4iw_dealloc(struct uld_ctx *ctx);
 struct ib_mw *c4iw_alloc_mw(struct ib_pd *pd, enum ib_mw_type type,
 			    struct ib_udata *udata);
 struct ib_mr *c4iw_reg_user_mr(struct ib_pd *pd, u64 start,