RDMA/bnxt_re: Wait for all the CQ events before freeing CQ data structures

Destroy CQ command to firmware returns the num_cnq_events as a
response. This indicates the driver about the number of CQ events
generated for this CQ. Driver should wait for all these events before
freeing the CQ host structures.  Also, add routine to clean all the
pending notification for the CQs getting destroyed. This avoids the
possibility of accessing the CQ data structures after its freed.

Fixes: 1ac5a40479 ("RDMA/bnxt_re: Add bnxt_re RoCE driver")
Link: https://lore.kernel.org/r/1584120842-3200-1-git-send-email-selvin.xavier@broadcom.com
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/bnxt_re/qplib_fp.c

@@ -43,6 +43,7 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/pci.h>
+#include <linux/delay.h>
 #include <linux/prefetch.h>
 #include <linux/if_ether.h>
 
@@ -231,6 +232,70 @@ static int bnxt_qplib_alloc_qp_hdr_buf(struct bnxt_qplib_res *res,
 	return rc;
 }
 
+static void clean_nq(struct bnxt_qplib_nq *nq, struct bnxt_qplib_cq *cq)
+{
+	struct bnxt_qplib_hwq *hwq = &nq->hwq;
+	struct nq_base *nqe, **nq_ptr;
+	int budget = nq->budget;
+	u32 sw_cons, raw_cons;
+	uintptr_t q_handle;
+	u16 type;
+
+	spin_lock_bh(&hwq->lock);
+	/* Service the NQ until empty */
+	raw_cons = hwq->cons;
+	while (budget--) {
+		sw_cons = HWQ_CMP(raw_cons, hwq);
+		nq_ptr = (struct nq_base **)hwq->pbl_ptr;
+		nqe = &nq_ptr[NQE_PG(sw_cons)][NQE_IDX(sw_cons)];
+		if (!NQE_CMP_VALID(nqe, raw_cons, hwq->max_elements))
+			break;
+
+		/*
+		 * The valid test of the entry must be done first before
+		 * reading any further.
+		 */
+		dma_rmb();
+
+		type = le16_to_cpu(nqe->info10_type) & NQ_BASE_TYPE_MASK;
+		switch (type) {
+		case NQ_BASE_TYPE_CQ_NOTIFICATION:
+		{
+			struct nq_cn *nqcne = (struct nq_cn *)nqe;
+
+			q_handle = le32_to_cpu(nqcne->cq_handle_low);
+			q_handle |= (u64)le32_to_cpu(nqcne->cq_handle_high)
+						     << 32;
+			if ((unsigned long)cq == q_handle) {
+				nqcne->cq_handle_low = 0;
+				nqcne->cq_handle_high = 0;
+				cq->cnq_events++;
+			}
+			break;
+		}
+		default:
+			break;
+		}
+		raw_cons++;
+	}
+	spin_unlock_bh(&hwq->lock);
+}
+
+/* Wait for receiving all NQEs for this CQ and clean the NQEs associated with
+ * this CQ.
+ */
+static void __wait_for_all_nqes(struct bnxt_qplib_cq *cq, u16 cnq_events)
+{
+	u32 retry_cnt = 100;
+
+	while (retry_cnt--) {
+		if (cnq_events == cq->cnq_events)
+			return;
+		usleep_range(50, 100);
+		clean_nq(cq->nq, cq);
+	}
+}
+
 static void bnxt_qplib_service_nq(unsigned long data)
 {
 	struct bnxt_qplib_nq *nq = (struct bnxt_qplib_nq *)data;
@@ -244,6 +309,7 @@ static void bnxt_qplib_service_nq(unsigned long data)
 	uintptr_t q_handle;
 	u16 type;
 
+	spin_lock_bh(&hwq->lock);
 	/* Service the NQ until empty */
 	raw_cons = hwq->cons;
 	while (budget--) {
@@ -269,6 +335,8 @@ static void bnxt_qplib_service_nq(unsigned long data)
 			q_handle |= (u64)le32_to_cpu(nqcne->cq_handle_high)
 						     << 32;
 			cq = (struct bnxt_qplib_cq *)(unsigned long)q_handle;
+			if (!cq)
+				break;
 			bnxt_qplib_armen_db(&cq->dbinfo,
 					    DBC_DBC_TYPE_CQ_ARMENA);
 			spin_lock_bh(&cq->compl_lock);
@@ -278,6 +346,7 @@ static void bnxt_qplib_service_nq(unsigned long data)
 			else
 				dev_warn(&nq->pdev->dev,
 					 "cqn - type 0x%x not handled\n", type);
+			cq->cnq_events++;
 			spin_unlock_bh(&cq->compl_lock);
 			break;
 		}
@@ -316,6 +385,7 @@ static void bnxt_qplib_service_nq(unsigned long data)
 		hwq->cons = raw_cons;
 		bnxt_qplib_ring_nq_db(&nq->nq_db.dbinfo, nq->res->cctx, true);
 	}
+	spin_unlock_bh(&hwq->lock);
 }
 
 static irqreturn_t bnxt_qplib_nq_irq(int irq, void *dev_instance)
@@ -2003,6 +2073,7 @@ int bnxt_qplib_destroy_cq(struct bnxt_qplib_res *res, struct bnxt_qplib_cq *cq)
 	struct bnxt_qplib_rcfw *rcfw = res->rcfw;
 	struct cmdq_destroy_cq req;
 	struct creq_destroy_cq_resp resp;
+	u16 total_cnq_events;
 	u16 cmd_flags = 0;
 	int rc;
 
@@ -2013,6 +2084,8 @@ int bnxt_qplib_destroy_cq(struct bnxt_qplib_res *res, struct bnxt_qplib_cq *cq)
 					  (void *)&resp, NULL, 0);
 	if (rc)
 		return rc;
+	total_cnq_events = le16_to_cpu(resp.total_cnq_events);
+	__wait_for_all_nqes(cq, total_cnq_events);
 	bnxt_qplib_free_hwq(res, &cq->hwq);
 	return 0;
 }

drivers/infiniband/hw/bnxt_re/qplib_fp.h

@@ -402,6 +402,7 @@ struct bnxt_qplib_cq {
  * of the same QP while manipulating the flush list.
  */
 	spinlock_t			flush_lock; /* QP flush management */
+	u16				cnq_events;
 };
 
 #define BNXT_QPLIB_MAX_IRRQE_ENTRY_SIZE	sizeof(struct xrrq_irrq)