RDMA/core: Add protection for shared CQs used by ULPs

A pre-step for adding shared CQs. Add the infrastructure to prevent shared
CQ users from altering the CQ configurations. For now all cqs are marked
as private (non-shared). The core driver should use the new force
functions to perform resize/destroy/moderation changes that are not
allowed for users of shared CQs.

Link: https://lore.kernel.org/r/1590568495-101621-2-git-send-email-yaminf@mellanox.comSigned-off-by: Yamin Friedman <yaminf@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/verbs.c

@@ -2005,6 +2005,9 @@ EXPORT_SYMBOL(__ib_create_cq);
 
 int rdma_set_cq_moderation(struct ib_cq *cq, u16 cq_count, u16 cq_period)
 {
+	if (cq->shared)
+		return -EOPNOTSUPP;
+
 	return cq->device->ops.modify_cq ?
 		cq->device->ops.modify_cq(cq, cq_count,
 					  cq_period) : -EOPNOTSUPP;
@@ -2013,6 +2016,9 @@ EXPORT_SYMBOL(rdma_set_cq_moderation);
 
 int ib_destroy_cq_user(struct ib_cq *cq, struct ib_udata *udata)
 {
+	if (WARN_ON_ONCE(cq->shared))
+		return -EOPNOTSUPP;
+
 	if (atomic_read(&cq->usecnt))
 		return -EBUSY;
 
@@ -2025,6 +2031,9 @@ EXPORT_SYMBOL(ib_destroy_cq_user);
 
 int ib_resize_cq(struct ib_cq *cq, int cqe)
 {
+	if (cq->shared)
+		return -EOPNOTSUPP;
+
 	return cq->device->ops.resize_cq ?
 		cq->device->ops.resize_cq(cq, cqe, NULL) : -EOPNOTSUPP;
 }

include/rdma/ib_verbs.h

@@ -1613,7 +1613,8 @@ struct ib_cq {
 
 	/* updated only by trace points */
 	ktime_t timestamp;
-	bool interrupt;
+	u8 interrupt:1;
+	u8 shared:1;
 
 	/*
 	 * Implementation details of the RDMA core, don't use in drivers:
@@ -3909,6 +3910,8 @@ static inline struct ib_cq *ib_alloc_cq_any(struct ib_device *dev,
  * ib_free_cq_user - Free kernel/user CQ
  * @cq: The CQ to free
  * @udata: Valid user data or NULL for kernel objects
+ *
+ * NOTE: This function shouldn't be called on shared CQs.
  */
 void ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata);