net: phy: fix regression with AX88772A PHY driver

Marek reports that a deadlock occurs with the AX88772A PHY used on the
ASIX USB network driver:

asix 1-1.4:1.0 (unnamed net_device) (uninitialized): PHY [usb-001:003:10] driver [Asix Electronics AX88772A] (irq=POLL)
Asix Electronics AX88772A usb-001:003:10: attached PHY driver(mii_bus:phy_addr=usb-001:003:10, irq=POLL)
asix 1-1.4:1.0 eth0: register 'asix' at usb-12110000.usb-1.4, ASIX AX88772 USB 2.0 Ethernet, a2:99:b6:cd:11:eb
asix 1-1.4:1.0 eth0: configuring for phy/internal link mode

============================================
WARNING: possible recursive locking detected
6.6.0-rc1-00239-g8da77df649c4-dirty #13949 Not tainted
--------------------------------------------
kworker/3:3/71 is trying to acquire lock:
c6c704cc (&dev->lock){+.+.}-{3:3}, at: phy_start_aneg+0x1c/0x38

but task is already holding lock:
c6c704cc (&dev->lock){+.+.}-{3:3}, at: phy_state_machine+0x100/0x2b8

This is because we now consistently call phy_process_state_change()
while holding phydev->lock, but the AX88772A PHY driver then goes on
to call phy_start_aneg() which tries to grab the same lock - causing
deadlock.

Fix this by exporting the unlocked version, and use this in the PHY
driver instead.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: ef113a60d0a9 ("net: phy: call phy_error_precise() while holding the lock")
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/E1qiEFs-007g7b-Lq@rmk-PC.armlinux.org.uk
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/phy/ax88796b.c b/drivers/net/phy/ax88796b.c
index 0f1e617a26c9154b2fda61956fe4689ad3ede911..eb74a8cf8df1c077670c3d84c37f7c872e37ff4b 100644 (file)
--- a/drivers/net/phy/ax88796b.c
+++ b/drivers/net/phy/ax88796b.c
@@ -90,7 +90,7 @@ static void asix_ax88772a_link_change_notify(struct phy_device *phydev)
         */
        if (phydev->state == PHY_NOLINK) {
                phy_init_hw(phydev);
-               phy_start_aneg(phydev);
+               _phy_start_aneg(phydev);
        }
 }
 

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 93a8676dd8d8b20bb48dbed6d7aa3e4b72a56fb5..a5fa077650e8383ddd65ff2fff0925fc5a6f32c8 100644 (file)
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -981,7 +981,7 @@ static int phy_check_link_status(struct phy_device *phydev)
  *   If the PHYCONTROL Layer is operating, we change the state to
  *   reflect the beginning of Auto-negotiation or forcing.
  */
-static int _phy_start_aneg(struct phy_device *phydev)
+int _phy_start_aneg(struct phy_device *phydev)
 {
        int err;
 
@@ -1002,6 +1002,7 @@ static int _phy_start_aneg(struct phy_device *phydev)
 
        return err;
 }
+EXPORT_SYMBOL(_phy_start_aneg);
 
 /**
  * phy_start_aneg - start auto-negotiation for this PHY device

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 1351b802ffcff16969e73fe6e4be9a150035a43b..3cc52826f18e94288f965b6b2526e481e1beee79 100644 (file)
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1736,6 +1736,7 @@ void phy_detach(struct phy_device *phydev);
 void phy_start(struct phy_device *phydev);
 void phy_stop(struct phy_device *phydev);
 int phy_config_aneg(struct phy_device *phydev);
+int _phy_start_aneg(struct phy_device *phydev);
 int phy_start_aneg(struct phy_device *phydev);
 int phy_aneg_done(struct phy_device *phydev);
 int phy_speed_down(struct phy_device *phydev, bool sync);