netdev - [PATCH net-next] net: phylink: force link down on major

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Message-Id: <E1twkqO-0006FI-Gm@rmk-PC.armlinux.org.uk>
Date: Mon, 24 Mar 2025 16:40:08 +0000
From: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
To: Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH net-next] net: phylink: force link down on major_config
 failure

If we fail to configure the MAC or PCS according to the desired mode,
do not allow the network link to come up until we have successfully
configured the MAC and PCS. This improves phylink's behaviour when an
error occurs.

Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
 drivers/net/phy/phylink.c | 42 +++++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 8 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 0f70a7f3dfcc..047ebb5d5f8c 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -83,6 +83,7 @@ struct phylink {
 	unsigned int pcs_state;
 
 	bool link_failed;
+	bool major_config_failed;
 	bool mac_supports_eee_ops;
 	bool mac_supports_eee;
 	bool phy_enable_tx_lpi;
@@ -1217,12 +1218,16 @@ static void phylink_major_config(struct phylink *pl, bool restart,
 		    phylink_an_mode_str(pl->req_link_an_mode),
 		    phy_modes(state->interface));
 
+	pl->major_config_failed = false;
+
 	if (pl->mac_ops->mac_select_pcs) {
 		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
 		if (IS_ERR(pcs)) {
 			phylink_err(pl,
 				    "mac_select_pcs unexpectedly failed: %pe\n",
 				    pcs);
+
+			pl->major_config_failed = true;
 			return;
 		}
 
@@ -1244,6 +1249,7 @@ static void phylink_major_config(struct phylink *pl, bool restart,
 		if (err < 0) {
 			phylink_err(pl, "mac_prepare failed: %pe\n",
 				    ERR_PTR(err));
+			pl->major_config_failed = true;
 			return;
 		}
 	}
@@ -1267,19 +1273,27 @@ static void phylink_major_config(struct phylink *pl, bool restart,
 
 	phylink_mac_config(pl, state);
 
-	if (pl->pcs)
-		phylink_pcs_post_config(pl->pcs, state->interface);
+	if (pl->pcs) {
+		err = phylink_pcs_post_config(pl->pcs, state->interface);
+		if (err < 0) {
+			phylink_err(pl, "pcs_post_config failed: %pe\n",
+				    ERR_PTR(err));
+
+			pl->major_config_failed = true;
+		}
+	}
 
 	if (pl->pcs_state == PCS_STATE_STARTING || pcs_changed)
 		phylink_pcs_enable(pl->pcs);
 
 	err = phylink_pcs_config(pl->pcs, pl->pcs_neg_mode, state,
 				 !!(pl->link_config.pause & MLO_PAUSE_AN));
-	if (err < 0)
-		phylink_err(pl, "pcs_config failed: %pe\n",
-			    ERR_PTR(err));
-	else if (err > 0)
+	if (err < 0) {
+		phylink_err(pl, "pcs_config failed: %pe\n", ERR_PTR(err));
+		pl->major_config_failed = true;
+	} else if (err > 0) {
 		restart = true;
+	}
 
 	if (restart)
 		phylink_pcs_an_restart(pl);
@@ -1287,16 +1301,22 @@ static void phylink_major_config(struct phylink *pl, bool restart,
 	if (pl->mac_ops->mac_finish) {
 		err = pl->mac_ops->mac_finish(pl->config, pl->act_link_an_mode,
 					      state->interface);
-		if (err < 0)
+		if (err < 0) {
 			phylink_err(pl, "mac_finish failed: %pe\n",
 				    ERR_PTR(err));
+
+			pl->major_config_failed = true;
+		}
 	}
 
 	if (pl->phydev && pl->phy_ib_mode) {
 		err = phy_config_inband(pl->phydev, pl->phy_ib_mode);
-		if (err < 0)
+		if (err < 0) {
 			phylink_err(pl, "phy_config_inband: %pe\n",
 				    ERR_PTR(err));
+
+			pl->major_config_failed = true;
+		}
 	}
 
 	if (pl->sfp_bus) {
@@ -1640,6 +1660,12 @@ static void phylink_resolve(struct work_struct *w)
 		}
 	}
 
+	/* If configuration of the interface failed, force the link down
+	 * until we get a successful configuration.
+	 */
+	if (pl->major_config_failed)
+		link_state.link = false;
+
 	if (link_state.link != cur_link_state) {
 		pl->old_link_state = link_state.link;
 		if (!link_state.link)
-- 
2.30.2