netdev - [PATCH net-next] net: phy: improve phy state checking

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Message-ID: <ccc9ddc4-2f49-1cfa-7165-f5f1f9459036@gmail.com>
Date:   Sun, 16 Dec 2018 13:26:53 +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>
Subject: [PATCH net-next] net: phy: improve phy state checking

Add helpers phy_is_started() and __phy_is_started() to avoid open-coded
checks whether PHY has been started. To make the check easier move
PHY_HALTED before PHY_UP in enum phy_state. Further improvements:

phy_start_aneg():
Return -EBUSY and print warning if function is called from a non-started
state (DOWN, READY, HALTED). Better check because function is exported
and drivers may use it incorrectly.

phy_interrupt():
Return IRQ_NONE also if state is DOWN or READY. We should never receive
an interrupt in one of these states, but better play safe.

phy_stop():
Just return and print a warning if PHY is in a non-started state.
This warning should help to identify drivers with unbalanced calls to
phy_start() / phy_stop().

phy_state_machine():
Schedule state machine run only if PHY is in a started state.
E.g. if state is READY we don't need the state machine, it will be
started by phy_start().

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/phy/phy.c | 38 +++++++++++++++++++++++++-------------
 include/linux/phy.h   | 24 +++++++++++++++++++++++-
 2 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index e24708f1f..ff16aab5e 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -59,6 +59,12 @@ static const char *phy_state_to_str(enum phy_state st)
 	return NULL;
 }
 
+static void phy_warn_state(struct phy_device *phydev)
+{
+	phydev_warn(phydev, "%s called from state %s\n", __func__,
+		    phy_state_to_str(phydev->state));
+}
+
 static void phy_link_up(struct phy_device *phydev)
 {
 	phydev->phy_link_change(phydev, true, true);
@@ -543,6 +549,12 @@ int phy_start_aneg(struct phy_device *phydev)
 
 	mutex_lock(&phydev->lock);
 
+	if (!__phy_is_started(phydev)) {
+		phy_warn_state(phydev);
+		err = -EBUSY;
+		goto out_unlock;
+	}
+
 	if (AUTONEG_DISABLE == phydev->autoneg)
 		phy_sanitize_settings(phydev);
 
@@ -553,13 +565,11 @@ int phy_start_aneg(struct phy_device *phydev)
 	if (err < 0)
 		goto out_unlock;
 
-	if (phydev->state != PHY_HALTED) {
-		if (AUTONEG_ENABLE == phydev->autoneg) {
-			err = phy_check_link_status(phydev);
-		} else {
-			phydev->state = PHY_FORCING;
-			phydev->link_timeout = PHY_FORCE_TIMEOUT;
-		}
+	if (phydev->autoneg == AUTONEG_ENABLE) {
+		err = phy_check_link_status(phydev);
+	} else {
+		phydev->state = PHY_FORCING;
+		phydev->link_timeout = PHY_FORCE_TIMEOUT;
 	}
 
 out_unlock:
@@ -709,7 +719,7 @@ void phy_stop_machine(struct phy_device *phydev)
 	cancel_delayed_work_sync(&phydev->state_queue);
 
 	mutex_lock(&phydev->lock);
-	if (phydev->state > PHY_UP && phydev->state != PHY_HALTED)
+	if (__phy_is_started(phydev))
 		phydev->state = PHY_UP;
 	mutex_unlock(&phydev->lock);
 }
@@ -760,7 +770,7 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat)
 {
 	struct phy_device *phydev = phy_dat;
 
-	if (PHY_HALTED == phydev->state)
+	if (!phy_is_started(phydev))
 		return IRQ_NONE;		/* It can't be ours.  */
 
 	if (phydev->drv->did_interrupt && !phydev->drv->did_interrupt(phydev))
@@ -842,15 +852,17 @@ void phy_stop(struct phy_device *phydev)
 {
 	mutex_lock(&phydev->lock);
 
-	if (PHY_HALTED == phydev->state)
-		goto out_unlock;
+	if (!__phy_is_started(phydev)) {
+		phy_warn_state(phydev);
+		mutex_unlock(&phydev->lock);
+		return;
+	}
 
 	if (phy_interrupt_is_valid(phydev))
 		phy_disable_interrupts(phydev);
 
 	phydev->state = PHY_HALTED;
 
-out_unlock:
 	mutex_unlock(&phydev->lock);
 
 	phy_state_machine(&phydev->state_queue.work);
@@ -984,7 +996,7 @@ void phy_state_machine(struct work_struct *work)
 	 * state machine would be pointless and possibly error prone when
 	 * called from phy_disconnect() synchronously.
 	 */
-	if (phy_polling_mode(phydev) && old_state != PHY_HALTED)
+	if (phy_polling_mode(phydev) && phy_is_started(phydev))
 		phy_queue_state_machine(phydev, PHY_STATE_TIME);
 }
 
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 8f927246a..da039f211 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -319,12 +319,12 @@ struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr);
 enum phy_state {
 	PHY_DOWN = 0,
 	PHY_READY,
+	PHY_HALTED,
 	PHY_UP,
 	PHY_RUNNING,
 	PHY_NOLINK,
 	PHY_FORCING,
 	PHY_CHANGELINK,
-	PHY_HALTED,
 	PHY_RESUMING
 };
 
@@ -669,6 +669,28 @@ phy_lookup_setting(int speed, int duplex, const unsigned long *mask,
 size_t phy_speeds(unsigned int *speeds, size_t size,
 		  unsigned long *mask);
 
+static inline bool __phy_is_started(struct phy_device *phydev)
+{
+	WARN_ON(!mutex_is_locked(&phydev->lock));
+
+	return phydev->state >= PHY_UP;
+}
+
+/**
+ * phy_is_started - Convenience function to check whether PHY is started
+ * @phydev: The phy_device struct
+ */
+static inline bool phy_is_started(struct phy_device *phydev)
+{
+	bool started;
+
+	mutex_lock(&phydev->lock);
+	started = __phy_is_started(phydev);
+	mutex_unlock(&phydev->lock);
+
+	return started;
+}
+
 void phy_resolve_aneg_linkmode(struct phy_device *phydev);
 
 /**
-- 
2.20.0