[dpdk-dev] [PATCH v3] ethdev: fix VLAN offloads set if no driver callback

["Wei Hu (Xavier)" <huwei013@chinasoftinc.com>]

From: "Wei Hu (Xavier)" <xavier.huwei@huawei.com>

Currently, there is a potential problem that changing the content of
dev->data->dev_conf.rxmode.offloads even when there is no vlan_offload_set
driver callback.

It is a good idea that prevent the side effect and make the API return
success if no change requested. This patch fixes the problem, the detail
information as below:
 - keep possibility to do dummy set even if there is no driver callback
 - do not touch Rx mode offloads in device data before checking the driver
   callback availability
 - ensure that Rx mode offloads are rolled back correctly if driver
   callback returns error

Fixes: dfebfc9882fb ("ethdev: support dynamic configuration of QinQ strip")
Cc: stable@dpdk.org

Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Signed-off-by: Chunsong Feng <fengchunsong@huawei.com>
Signed-off-by: Min Wang (Jushui) <wangmin3@huawei.com>
Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>
---
v2 -> v3:
	1. Update the commit log and titile of the patch according to
	   Andrew Rybchenko's comments. The related link as below:
	   http://patches.dpdk.org/patch/64825/
v1 -> v2:
	1. Update the modification according to Ferruh Yigit's comment.
	   The related link as below:
	   http://patches.dpdk.org/patch/64779/
	2. Update the commit log and title of the patch.
---
 lib/librte_ethdev/rte_ethdev.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index aec2d0f70..9232503f7 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -3253,53 +3253,53 @@ rte_eth_dev_set_vlan_offload(uint16_t port_id, int offload_mask)
 	int mask = 0;
 	int cur, org = 0;
 	uint64_t orig_offloads;
-	uint64_t *dev_offloads;
+	uint64_t dev_offloads;
 
 	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
 	dev = &rte_eth_devices[port_id];
 
 	/* save original values in case of failure */
 	orig_offloads = dev->data->dev_conf.rxmode.offloads;
-	dev_offloads = &dev->data->dev_conf.rxmode.offloads;
+	dev_offloads = orig_offloads;
 
 	/*check which option changed by application*/
 	cur = !!(offload_mask & ETH_VLAN_STRIP_OFFLOAD);
-	org = !!(*dev_offloads & DEV_RX_OFFLOAD_VLAN_STRIP);
+	org = !!(dev_offloads & DEV_RX_OFFLOAD_VLAN_STRIP);
 	if (cur != org) {
 		if (cur)
-			*dev_offloads |= DEV_RX_OFFLOAD_VLAN_STRIP;
+			dev_offloads |= DEV_RX_OFFLOAD_VLAN_STRIP;
 		else
-			*dev_offloads &= ~DEV_RX_OFFLOAD_VLAN_STRIP;
+			dev_offloads &= ~DEV_RX_OFFLOAD_VLAN_STRIP;
 		mask |= ETH_VLAN_STRIP_MASK;
 	}
 
 	cur = !!(offload_mask & ETH_VLAN_FILTER_OFFLOAD);
-	org = !!(*dev_offloads & DEV_RX_OFFLOAD_VLAN_FILTER);
+	org = !!(dev_offloads & DEV_RX_OFFLOAD_VLAN_FILTER);
 	if (cur != org) {
 		if (cur)
-			*dev_offloads |= DEV_RX_OFFLOAD_VLAN_FILTER;
+			dev_offloads |= DEV_RX_OFFLOAD_VLAN_FILTER;
 		else
-			*dev_offloads &= ~DEV_RX_OFFLOAD_VLAN_FILTER;
+			dev_offloads &= ~DEV_RX_OFFLOAD_VLAN_FILTER;
 		mask |= ETH_VLAN_FILTER_MASK;
 	}
 
 	cur = !!(offload_mask & ETH_VLAN_EXTEND_OFFLOAD);
-	org = !!(*dev_offloads & DEV_RX_OFFLOAD_VLAN_EXTEND);
+	org = !!(dev_offloads & DEV_RX_OFFLOAD_VLAN_EXTEND);
 	if (cur != org) {
 		if (cur)
-			*dev_offloads |= DEV_RX_OFFLOAD_VLAN_EXTEND;
+			dev_offloads |= DEV_RX_OFFLOAD_VLAN_EXTEND;
 		else
-			*dev_offloads &= ~DEV_RX_OFFLOAD_VLAN_EXTEND;
+			dev_offloads &= ~DEV_RX_OFFLOAD_VLAN_EXTEND;
 		mask |= ETH_VLAN_EXTEND_MASK;
 	}
 
 	cur = !!(offload_mask & ETH_QINQ_STRIP_OFFLOAD);
-	org = !!(*dev_offloads & DEV_RX_OFFLOAD_QINQ_STRIP);
+	org = !!(dev_offloads & DEV_RX_OFFLOAD_QINQ_STRIP);
 	if (cur != org) {
 		if (cur)
-			*dev_offloads |= DEV_RX_OFFLOAD_QINQ_STRIP;
+			dev_offloads |= DEV_RX_OFFLOAD_QINQ_STRIP;
 		else
-			*dev_offloads &= ~DEV_RX_OFFLOAD_QINQ_STRIP;
+			dev_offloads &= ~DEV_RX_OFFLOAD_QINQ_STRIP;
 		mask |= ETH_QINQ_STRIP_MASK;
 	}
 
@@ -3308,10 +3308,11 @@ rte_eth_dev_set_vlan_offload(uint16_t port_id, int offload_mask)
 		return ret;
 
 	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->vlan_offload_set, -ENOTSUP);
+	dev->data->dev_conf.rxmode.offloads = dev_offloads;
 	ret = (*dev->dev_ops->vlan_offload_set)(dev, mask);
 	if (ret) {
 		/* hit an error restore  original values */
-		*dev_offloads = orig_offloads;
+		dev->data->dev_conf.rxmode.offloads = orig_offloads;
 	}
 
 	return eth_err(port_id, ret);
-- 
2.23.0