net: eqos: Fix race condition with rx own bit.

Resolved race condition where there could be dma
outstanding for same rx descriptor which has own
bit set to zero.

Bug 1762280

Change-Id: I53a9361037d1783b030db78ddd249295b61651e1
Signed-off-by: Dave Lim <dlim@nvidia.com>
Reviewed-on: http://git-master/r/1144836
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Ajay Gupta <ajayg@nvidia.com>
Reviewed-by: Anirban Ray <aray@nvidia.com>
Reviewed-by: Ashutosh Jha <ajha@nvidia.com>

3 files changed, 24 insertions, 4 deletions

diff --git a/drivers/net/ethernet/nvidia/eqos/dev.c b/drivers/net/ethernet/nvidia/eqos/dev.c
index 41cb8dad1..16aabbc90 100644
--- a/drivers/net/ethernet/nvidia/eqos/dev.c
+++ b/drivers/net/ethernet/nvidia/eqos/dev.c
@@ -29,7 +29,7 @@
  * DAMAGE.
  * ========================================================================= */
 /*
- * Copyright (c) 2015, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2015-2016, NVIDIA CORPORATION.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -2869,6 +2869,9 @@ static void rx_descriptor_init(struct eqos_prv_data *pdata, UINT qinx)
         /* update the starting address of desc chain/ring */
         DMA_RDLAR_WR(qinx, GET_RX_DESC_DMA_ADDR(qinx, start_index));
 
+        prx_ring->hw_last_rx_desc_addr =
+                GET_RX_DESC_DMA_ADDR(qinx, start_index);
+
         DBGPR("<--rx_descriptor_init\n");
 }
 
diff --git a/drivers/net/ethernet/nvidia/eqos/drv.c b/drivers/net/ethernet/nvidia/eqos/drv.c
index 617027371..2c56f3bda 100644
--- a/drivers/net/ethernet/nvidia/eqos/drv.c
+++ b/drivers/net/ethernet/nvidia/eqos/drv.c
@@ -29,7 +29,7 @@
  * DAMAGE.
  * ========================================================================= */
 /*
- * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2015-2016, NVIDIA CORPORATION.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -2338,18 +2338,33 @@ static int process_rx_completions(struct eqos_prv_data *pdata,
         struct s_rx_desc *prx_desc = NULL;
         UINT pkt_len;
         UINT err_bits = EQOS_RDESC3_ES_BITS;
+        u32 sw_cur_rx_desc_addr = 0;
+        u32 hw_cur_rx_desc_addr = 0;
 
         int ret;
 
         DBGPR("-->%s(): qinx = %u, quota = %d\n", __func__, qinx, quota);
 
+        hw_cur_rx_desc_addr = prx_ring->hw_last_rx_desc_addr;
         while (received < quota) {
                 prx_swcx_desc = GET_RX_BUF_PTR(qinx, prx_ring->cur_rx);
                 prx_desc = GET_RX_DESC_PTR(qinx, prx_ring->cur_rx);
 
+                sw_cur_rx_desc_addr =
+                        GET_RX_DESC_DMA_ADDR(qinx, prx_ring->cur_rx);
+
                 /* check for data availability */
                 if (!(prx_desc->rdes3 & EQOS_RDESC3_OWN) &&
-                        prx_swcx_desc->skb) {
+                    prx_swcx_desc->skb) {
+                        if (hw_cur_rx_desc_addr == sw_cur_rx_desc_addr) {
+                                DMA_CHRDR_RD(qinx,
+                                             prx_ring->hw_last_rx_desc_addr);
+                                if (prx_ring->hw_last_rx_desc_addr ==
+                                    hw_cur_rx_desc_addr)
+                                        break;
+                                hw_cur_rx_desc_addr =
+                                        prx_ring->hw_last_rx_desc_addr;
+                        }
 #ifdef EQOS_ENABLE_RX_DESC_DUMP
                         dump_rx_desc(qinx, prx_desc, prx_ring->cur_rx);
 #endif
diff --git a/drivers/net/ethernet/nvidia/eqos/yheader.h b/drivers/net/ethernet/nvidia/eqos/yheader.h
index 2e4e5b7e5..bc1cb7823 100644
--- a/drivers/net/ethernet/nvidia/eqos/yheader.h
+++ b/drivers/net/ethernet/nvidia/eqos/yheader.h
@@ -29,7 +29,7 @@
  * DAMAGE.
  * ========================================================================= */
 /*
- * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2015-2016, NVIDIA CORPORATION.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -1019,6 +1019,8 @@ struct rx_ring {
         /* for rx vlan stripping */
         u32 rx_inner_vlan_strip;
         u32 rx_outer_vlan_strip;
+
+        u32 hw_last_rx_desc_addr;
 };
 
 struct eqos_rx_queue {