netdev - [PATCH net-next] net: phy: avoid kernel warning dump when stopping an errored PHY

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Date: Mon, 22 May 2023 16:58:08 +0100
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>,
	Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org
Subject: [PATCH net-next] net: phy: avoid kernel warning dump when stopping an
 errored PHY

When taking a network interface down (or removing a SFP module) after
the PHY has encountered an error, phy_stop() complains incorrectly
that it was called from HALTED state.

The reason this is incorrect is that the network driver will have
called phy_start() when the interface was brought up, and the fact
that the PHY has a problem bears no relationship to the administrative
state of the interface. Taking the interface administratively down
(which calls phy_stop()) is always the right thing to do after a
successful phy_start() call, whether or not the PHY has encountered
an error.

Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
 drivers/net/phy/phy.c | 11 +++++++----
 include/linux/phy.h   |  7 +++++--
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 0c0df38cd1ab..bdf00b2b2c1d 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -52,6 +52,7 @@ static const char *phy_state_to_str(enum phy_state st)
 	PHY_STATE_STR(NOLINK)
 	PHY_STATE_STR(CABLETEST)
 	PHY_STATE_STR(HALTED)
+	PHY_STATE_STR(ERROR)
 	}
 
 	return NULL;
@@ -1184,7 +1185,7 @@ void phy_stop_machine(struct phy_device *phydev)
 static void phy_process_error(struct phy_device *phydev)
 {
 	mutex_lock(&phydev->lock);
-	phydev->state = PHY_HALTED;
+	phydev->state = PHY_ERROR;
 	mutex_unlock(&phydev->lock);
 
 	phy_trigger_machine(phydev);
@@ -1198,10 +1199,10 @@ static void phy_error_precise(struct phy_device *phydev,
 }
 
 /**
- * phy_error - enter HALTED state for this PHY device
+ * phy_error - enter ERROR state for this PHY device
  * @phydev: target phy_device struct
  *
- * Moves the PHY to the HALTED state in response to a read
+ * Moves the PHY to the ERROR state in response to a read
  * or write error, and tells the controller the link is down.
  * Must not be called from interrupt context, or while the
  * phydev->lock is held.
@@ -1326,7 +1327,8 @@ void phy_stop(struct phy_device *phydev)
 	struct net_device *dev = phydev->attached_dev;
 	enum phy_state old_state;
 
-	if (!phy_is_started(phydev) && phydev->state != PHY_DOWN) {
+	if (!phy_is_started(phydev) && phydev->state != PHY_DOWN &&
+	    phydev->state != PHY_ERROR) {
 		WARN(1, "called from state %s\n",
 		     phy_state_to_str(phydev->state));
 		return;
@@ -1443,6 +1445,7 @@ void phy_state_machine(struct work_struct *work)
 		}
 		break;
 	case PHY_HALTED:
+	case PHY_ERROR:
 		if (phydev->link) {
 			phydev->link = 0;
 			phy_link_down(phydev);
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 2da87a36200d..7addde5d14c0 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -497,14 +497,17 @@ struct phy_device *mdiobus_scan_c22(struct mii_bus *bus, int addr);
  * Once complete, move to UP to restart the PHY.
  * - phy_stop aborts the running test and moves to @PHY_HALTED
  *
- * @PHY_HALTED: PHY is up, but no polling or interrupts are done. Or
- * PHY is in an error state.
+ * @PHY_HALTED: PHY is up, but no polling or interrupts are done.
  * - phy_start moves to @PHY_UP
+ *
+ * @PHY_ERROR: PHY is up, but is in an error state.
+ * - phy_stop moves to @PHY_HALTED
  */
 enum phy_state {
 	PHY_DOWN = 0,
 	PHY_READY,
 	PHY_HALTED,
+	PHY_ERROR,
 	PHY_UP,
 	PHY_RUNNING,
 	PHY_NOLINK,
-- 
2.30.2