[PATCH net-next 5/7] bnge: Quiesce NQ0 around ring teardown in bnge_free_core()

[Bhargava Marreddy <bhargava.marreddy@broadcom.com>]

Add bnge_quiesce_nq0() and bnge_resume_nq0() helpers to temporarily disable
and re-enable NQ0 NAPI. Use these helpers to bracket ring teardown in
bnge_free_core() and ring rebuild in bnge_alloc_core().

Both helpers currently no-op, since no bnge_napi has BNGE_NAPI_FLAG_NQ0 set
yet. The next patch creates NQ0 during probe and sets this flag, at which
point these helpers become load-bearing: because NQ0 will remain active
while administratively down, its NAPI is not disabled by the standard close
paths, so temporarily quiescing it during core resource free/rebuild windows
is required to prevent stray completions from accessing uninitialized or
freed memory.

Signed-off-by: Bhargava Marreddy <bhargava.marreddy@broadcom.com>
Reviewed-by: Vikas Gupta <vikas.gupta@broadcom.com>
Reviewed-by: Rajashekar Hudumula <rajashekar.hudumula@broadcom.com>
---
 .../net/ethernet/broadcom/bnge/bnge_netdev.c  | 70 ++++++++++++++-----
 .../net/ethernet/broadcom/bnge/bnge_netdev.h  | 10 +++
 2 files changed, 61 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnge/bnge_netdev.c b/drivers/net/ethernet/broadcom/bnge/bnge_netdev.c
index dc3d51f31e5e..10d54568f2c5 100644
--- a/drivers/net/ethernet/broadcom/bnge/bnge_netdev.c
+++ b/drivers/net/ethernet/broadcom/bnge/bnge_netdev.c
@@ -442,6 +442,25 @@ static void bnge_sp_task(struct work_struct *work)
 	netdev_unlock(bn->netdev);
 }
 
+static void bnge_db_nq_arm(struct bnge_net *bn,
+			   struct bnge_db_info *db, u32 idx)
+{
+	bnge_writeq(bn->bd, db->db_key64 | DBR_TYPE_NQ_ARM |
+		    DB_RING_IDX(db, idx), db->doorbell);
+}
+
+static void bnge_db_nq(struct bnge_net *bn, struct bnge_db_info *db, u32 idx)
+{
+	bnge_writeq(bn->bd, db->db_key64 | DBR_TYPE_NQ_MASK |
+		    DB_RING_IDX(db, idx), db->doorbell);
+}
+
+static void bnge_db_cq(struct bnge_net *bn, struct bnge_db_info *db, u32 idx)
+{
+	bnge_writeq(bn->bd, db->db_key64 | DBR_TYPE_CQ_ARMALL |
+		    DB_RING_IDX(db, idx), db->doorbell);
+}
+
 static void bnge_free_nq_desc_arr(struct bnge_nq_ring_info *nqr)
 {
 	struct bnge_ring_struct *ring = &nqr->ring_struct;
@@ -563,6 +582,34 @@ static void bnge_free_nq_tree(struct bnge_net *bn)
 	}
 }
 
+static void bnge_quiesce_nq0(struct bnge_net *bn)
+{
+	struct bnge_napi *bnapi = bn->bnapi[BNGE_NQ0_NAPI_IDX];
+	struct bnge_nq_ring_info *nqr = &bnapi->nq_ring;
+	struct bnge_ring_struct *ring;
+	struct bnge_dev *bd = bn->bd;
+
+	if (!BNGE_NQ0_NAPI(bnapi))
+		return;
+
+	ring = &nqr->ring_struct;
+	bnge_db_nq(bn, &nqr->nq_db, nqr->nq_raw_cons);
+	synchronize_irq(bd->irq_tbl[ring->map_idx].vector);
+	napi_disable_locked(&bnapi->napi);
+}
+
+static void bnge_resume_nq0(struct bnge_net *bn)
+{
+	struct bnge_napi *bnapi = bn->bnapi[BNGE_NQ0_NAPI_IDX];
+	struct bnge_nq_ring_info *nqr = &bnapi->nq_ring;
+
+	if (!BNGE_NQ0_NAPI(bnapi))
+		return;
+
+	napi_enable_locked(&bnapi->napi);
+	bnge_db_nq_arm(bn, &nqr->nq_db, nqr->nq_raw_cons);
+}
+
 static int alloc_one_cp_ring(struct bnge_net *bn,
 			     struct bnge_cp_ring_info *cpr)
 {
@@ -1253,6 +1300,7 @@ static void bnge_clear_bnapi_queues(struct bnge_net *bn)
 static void bnge_free_core(struct bnge_net *bn)
 {
 	bnge_free_vnic_attributes(bn);
+	bnge_quiesce_nq0(bn);
 	bnge_free_tx_rings(bn);
 	bnge_free_rx_rings(bn);
 	bnge_free_nq_tree(bn);
@@ -1268,6 +1316,7 @@ static void bnge_free_core(struct bnge_net *bn)
 	bn->rx_ring = NULL;
 
 	bnge_clear_bnapi_queues(bn);
+	bnge_resume_nq0(bn);
 }
 
 static int bnge_alloc_core(struct bnge_net *bn)
@@ -1345,7 +1394,9 @@ static int bnge_alloc_core(struct bnge_net *bn)
 	if (rc)
 		goto err_free_core;
 
+	bnge_quiesce_nq0(bn);
 	rc = bnge_alloc_nq_tree(bn);
+	bnge_resume_nq0(bn);
 	if (rc)
 		goto err_free_core;
 
@@ -1372,25 +1423,6 @@ u32 bnge_cp_ring_for_tx(struct bnge_tx_ring_info *txr)
 	return txr->tx_cpr->ring_struct.fw_ring_id;
 }
 
-static void bnge_db_nq_arm(struct bnge_net *bn,
-			   struct bnge_db_info *db, u32 idx)
-{
-	bnge_writeq(bn->bd, db->db_key64 | DBR_TYPE_NQ_ARM |
-		    DB_RING_IDX(db, idx), db->doorbell);
-}
-
-static void bnge_db_nq(struct bnge_net *bn, struct bnge_db_info *db, u32 idx)
-{
-	bnge_writeq(bn->bd, db->db_key64 | DBR_TYPE_NQ_MASK |
-		    DB_RING_IDX(db, idx), db->doorbell);
-}
-
-static void bnge_db_cq(struct bnge_net *bn, struct bnge_db_info *db, u32 idx)
-{
-	bnge_writeq(bn->bd, db->db_key64 | DBR_TYPE_CQ_ARMALL |
-		    DB_RING_IDX(db, idx), db->doorbell);
-}
-
 static int bnge_cp_num_to_irq_num(struct bnge_net *bn, int n)
 {
 	struct bnge_napi *bnapi = bn->bnapi[n];
diff --git a/drivers/net/ethernet/broadcom/bnge/bnge_netdev.h b/drivers/net/ethernet/broadcom/bnge/bnge_netdev.h
index 476b5bab96fe..4d84f109ad5f 100644
--- a/drivers/net/ethernet/broadcom/bnge/bnge_netdev.h
+++ b/drivers/net/ethernet/broadcom/bnge/bnge_netdev.h
@@ -539,6 +539,14 @@ struct bnge_tx_ring_info {
 	struct bnge_ring_struct	tx_ring_struct;
 };
 
+#define BNGE_NQ0_NAPI_IDX	0
+
+enum bnge_napi_flag {
+	BNGE_NAPI_FLAG_NQ0,
+};
+
+#define BNGE_NQ0_NAPI(bnapi)	(test_bit(BNGE_NAPI_FLAG_NQ0, &(bnapi)->flags))
+
 struct bnge_napi {
 	struct napi_struct		napi;
 	struct bnge_net			*bn;
@@ -555,6 +563,8 @@ struct bnge_napi {
 #define BNGE_TX_CMP_EVENT		0x10
 	bool				in_reset;
 	bool				tx_fault;
+
+	unsigned long			flags;
 };
 
 #define INVALID_STATS_CTX_ID	-1
-- 
2.47.3