[PATCH 5/5] ice: use element-by-element comparison for DCB config changes

[Aleksandr Loktionov <aleksandr.loktionov@intel.com>]

Comparing two ice_dcbx_cfg structs with memcmp() is unreliable on
non-packed structs due to uninitialised padding bytes.  The HW DCB
path already has ice_dcb_need_recfg() that compares fields
individually; export it and use it in the SW DCB netlink setters
(setets, setpfc, setapp, cee_set_all) instead of the unsafe memcmp.

Remove the now-redundant memcmp check from ice_pf_dcb_cfg() so that
function always attempts the HW reconfiguration when called.

Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_dcb_lib.c | 13 ++-------
 drivers/net/ethernet/intel/ice/ice_dcb_lib.h |  2 ++
 drivers/net/ethernet/intel/ice/ice_dcb_nl.c  | 30 ++++++++++++++++++--
 3 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_dcb_lib.c b/drivers/net/ethernet/intel/ice/ice_dcb_lib.c
index bd77f1c..2e85fae 100644
--- a/drivers/net/ethernet/intel/ice/ice_dcb_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_dcb_lib.c
@@ -353,15 +353,11 @@ int ice_pf_dcb_cfg(struct ice_pf *pf, struct ice_dcbx_cfg *new_cfg, bool locked)
 	struct ice_dcbx_cfg *old_cfg, *curr_cfg;
 	struct device *dev = ice_pf_to_dev(pf);
 	struct iidc_rdma_event *event;
-	int ret = ICE_DCB_NO_HW_CHG;
 	struct ice_vsi *pf_vsi;
+	int ret;
 
 	curr_cfg = &pf->hw.port_info->qos_cfg.local_dcbx_cfg;
 
-	/* FW does not care if change happened */
-	if (!pf->hw.port_info->qos_cfg.is_sw_lldp)
-		ret = ICE_DCB_HW_CHG_RST;
-
 	/* Enable DCB tagging only when more than one TC */
 	if (ice_dcb_get_num_tc(new_cfg) > 1) {
 		dev_dbg(dev, "DCB tagging enabled (num TC > 1)\n");
@@ -377,11 +373,6 @@ int ice_pf_dcb_cfg(struct ice_pf *pf, struct ice_dcbx_cfg *new_cfg, bool locked)
 		clear_bit(ICE_FLAG_DCB_ENA, pf->flags);
 	}
 
-	if (!memcmp(new_cfg, curr_cfg, sizeof(*new_cfg))) {
-		dev_dbg(dev, "No change in DCB config required\n");
-		return ret;
-	}
-
 	if (ice_dcb_bwchk(pf, new_cfg))
 		return -EINVAL;
 
@@ -481,7 +472,7 @@ static void ice_cfg_etsrec_defaults(struct ice_port_info *pi)
  * @old_cfg: current DCB config
  * @new_cfg: new DCB config
  */
-static bool
+bool
 ice_dcb_need_recfg(struct ice_pf *pf, struct ice_dcbx_cfg *old_cfg,
 		   struct ice_dcbx_cfg *new_cfg)
 {
diff --git a/drivers/net/ethernet/intel/ice/ice_dcb_lib.h b/drivers/net/ethernet/intel/ice/ice_dcb_lib.h
index da9ba81..a7eaa2f9 100644
--- a/drivers/net/ethernet/intel/ice/ice_dcb_lib.h
+++ b/drivers/net/ethernet/intel/ice/ice_dcb_lib.h
@@ -20,6 +20,8 @@ u8 ice_dcb_get_num_tc(struct ice_dcbx_cfg *dcbcfg);
 void ice_vsi_set_dcb_tc_cfg(struct ice_vsi *vsi);
 bool ice_is_pfc_causing_hung_q(struct ice_pf *pf, unsigned int txqueue);
 u8 ice_dcb_get_tc(struct ice_vsi *vsi, int queue_index);
+bool ice_dcb_need_recfg(struct ice_pf *pf, struct ice_dcbx_cfg *old_cfg,
+			struct ice_dcbx_cfg *new_cfg);
 int
 ice_pf_dcb_cfg(struct ice_pf *pf, struct ice_dcbx_cfg *new_cfg, bool locked);
 int ice_dcb_bwchk(struct ice_pf *pf, struct ice_dcbx_cfg *dcbcfg);
diff --git a/drivers/net/ethernet/intel/ice/ice_dcb_nl.c b/drivers/net/ethernet/intel/ice/ice_dcb_nl.c
index a10c1c8d..13a52c1 100644
--- a/drivers/net/ethernet/intel/ice/ice_dcb_nl.c
+++ b/drivers/net/ethernet/intel/ice/ice_dcb_nl.c
@@ -108,11 +108,17 @@ static int ice_dcbnl_setets(struct net_device *netdev, struct ieee_ets *ets)
 	if (!bwrec)
 		new_cfg->etsrec.tcbwtable[0] = 100;
 
+	if (!ice_dcb_need_recfg(pf, &pf->hw.port_info->qos_cfg.local_dcbx_cfg,
+				new_cfg)) {
+		err = ICE_DCB_NO_HW_CHG;
+		goto ets_out;
+	}
+
 	err = ice_pf_dcb_cfg(pf, new_cfg, true);
 	/* return of zero indicates new cfg applied */
-	if (err == ICE_DCB_HW_CHG_RST)
+	if (!err)
 		ice_dcbnl_devreset(netdev);
-	if (err == ICE_DCB_NO_HW_CHG)
+	else if (err == ICE_DCB_NO_HW_CHG)
 		err = ICE_DCB_HW_CHG_RST;
 
 ets_out:
@@ -287,11 +293,18 @@ static int ice_dcbnl_setpfc(struct net_device *netdev, struct ieee_pfc *pfc)
 
 	new_cfg->pfc.pfcena = pfc->pfc_en;
 
+	if (!ice_dcb_need_recfg(pf, &pf->hw.port_info->qos_cfg.local_dcbx_cfg,
+				new_cfg)) {
+		err = ICE_DCB_NO_HW_CHG;
+		goto pfc_out;
+	}
+
 	err = ice_pf_dcb_cfg(pf, new_cfg, true);
 	if (err == ICE_DCB_HW_CHG_RST)
 		ice_dcbnl_devreset(netdev);
 	if (err == ICE_DCB_NO_HW_CHG)
 		err = ICE_DCB_HW_CHG_RST;
+pfc_out:
 	mutex_unlock(&pf->tc_mutex);
 	return err;
 }
@@ -845,6 +858,12 @@ static int ice_dcbnl_setapp(struct net_device *netdev, struct dcb_app *app)
 	new_cfg->dscp_map[app->protocol] = app->priority;
 	new_cfg->app[new_cfg->numapps++] = new_app;
 
+	if (!ice_dcb_need_recfg(pf, &pf->hw.port_info->qos_cfg.local_dcbx_cfg,
+				new_cfg)) {
+		ret = ICE_DCB_NO_HW_CHG;
+		goto setapp_out;
+	}
+
 	ret = ice_pf_dcb_cfg(pf, new_cfg, true);
 	/* return of zero indicates new cfg applied */
 	if (ret == ICE_DCB_HW_CHG_RST)
@@ -991,8 +1010,15 @@ static u8 ice_dcbnl_cee_set_all(struct net_device *netdev)
 
 	mutex_lock(&pf->tc_mutex);
 
+	if (!ice_dcb_need_recfg(pf, &pf->hw.port_info->qos_cfg.local_dcbx_cfg,
+				new_cfg)) {
+		err = ICE_DCB_NO_HW_CHG;
+		goto out;
+	}
+
 	err = ice_pf_dcb_cfg(pf, new_cfg, true);
 
+out:
 	mutex_unlock(&pf->tc_mutex);
 	return (err != ICE_DCB_HW_CHG_RST) ? ICE_DCB_NO_HW_CHG : err;
 }
-- 
2.52.0