[PATCH 5.7 032/265] net: phylink: fix ethtool -A with attached PHYs

Sasha Levin
2020-06-29T21:31:55Z

From: Russell King <rmk+kernel@armlinux.org.uk>

[ Upstream commit c718af2d00a37587b09e5958d142da7569f3d55b ]

Fix a phylink's ethtool set_pauseparam support deadlock caused by phylib
interacting with phylink: we must not hold the state lock while calling
phylib functions that may call into phylink_phy_change().

Fixes: f904f15ea9b5 ("net: phylink: allow ethtool -A to change flow control advertisement")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/phy/phylink.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 34ca12aec61b3..b0ddeab2a8d2f 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1519,18 +1519,20 @@ int phylink_ethtool_set_pauseparam(struct phylink *pl,
linkmode_set_pause(config->advertising, pause->tx_pause,
pause->rx_pause);

- /* If we have a PHY, phylib will call our link state function if the
- * mode has changed, which will trigger a resolve and update the MAC
- * configuration.
+ if (!pl->phydev && !test_bit(PHYLINK_DISABLE_STOPPED,
+ &pl->phylink_disable_state))
+ phylink_pcs_config(pl, true, &pl->link_config);
+
+ mutex_unlock(&pl->state_mutex);
+
+ /* If we have a PHY, a change of the pause frame advertisement will
+ * cause phylib to renegotiate (if AN is enabled) which will in turn
+ * call our phylink_phy_change() and trigger a resolve. Note that
+ * we can't hold our state mutex while calling phy_set_asym_pause().
*/
- if (pl->phydev) {
+ if (pl->phydev)
phy_set_asym_pause(pl->phydev, pause->rx_pause,
pause->tx_pause);
- } else if (!test_bit(PHYLINK_DISABLE_STOPPED,
- &pl->phylink_disable_state)) {
- phylink_pcs_config(pl, true, &pl->link_config);
- }
- mutex_unlock(&pl->state_mutex);

return 0;
}
--
2.25.1