netdev - [PATCH net-next v3 2/4] net: phy: warn if phy

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Message-ID: <8e610c04-f21a-a73a-12a9-02b361e26da8@gmail.com>
Date:   Wed, 23 Jan 2019 07:30:38 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "S-k, Shyam-sundar" <Shyam-sundar.S-k@....com>
Subject: [PATCH net-next v3 2/4] net: phy: warn if phy_start is called from
 invalid state

phy_start() should be called from states PHY_READY or PHY_HALTED only.
Check for this to detect misbehaving drivers. Also the state machine
should be started only when being called from one of the valid states.

Some more background:
For all invalid states phy_start() basically was a no-op. All it did
was triggering a state machine run, but for all "running" states the
poll loop was active anyway. And if called from PHY_DOWN, the state
machine does nothing.

v3:
- extended commit message

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/phy/phy.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 3df6aadc5..fd928979b 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -861,9 +861,16 @@ void phy_start(struct phy_device *phydev)
 
 	mutex_lock(&phydev->lock);
 
+	if (phydev->state != PHY_READY && phydev->state != PHY_HALTED) {
+		WARN(1, "called from state %s\n",
+		     phy_state_to_str(phydev->state));
+		goto out;
+	}
+
 	switch (phydev->state) {
 	case PHY_READY:
 		phydev->state = PHY_UP;
+		phy_start_machine(phydev);
 		break;
 	case PHY_HALTED:
 		/* if phy was suspended, bring the physical link up again */
@@ -877,13 +884,13 @@ void phy_start(struct phy_device *phydev)
 		}
 
 		phydev->state = PHY_RESUMING;
+		phy_start_machine(phydev);
 		break;
 	default:
 		break;
 	}
+out:
 	mutex_unlock(&phydev->lock);
-
-	phy_start_machine(phydev);
 }
 EXPORT_SYMBOL(phy_start);
 
-- 
2.20.1