[PATCH net 1/3] net: phylink: allow stopping a suspended instance

[James Hilliard <james.hilliard1@gmail.com>]

A MAC which cannot restore its hardware after system sleep may need to
close the network device instead of calling phylink_resume(). Without MAC
Wake-on-LAN, phylink_suspend() has already stopped the PHY and PCS, so
another phylink_stop() repeats their shutdown. With MAC Wake-on-LAN, the
saved link-up state still needs a matching mac_link_down(), and leaving
PHYLINK_DISABLE_MAC_WOL set prevents a subsequent start from resolving
the link.

Allow phylink_stop() to finish shutdown directly from either suspended
state. Leave an already stopped instance alone. For MAC Wake-on-LAN,
stop resolution, drain pending resolve work, complete the deferred
link-down and clear the WoL disable bit while retaining the stopped bit.
This does not restart the PHY, reconfigure the MAC or bring its link up.

Fixes: f97493657c63 ("net: phylink: add suspend/resume support")
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/net/phy/phylink.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index a1458da8111b..8f9278112623 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -2495,11 +2495,17 @@ EXPORT_SYMBOL_GPL(phylink_start);
  *
  * This will synchronously bring down the link if the link is not already
  * down (in other words, it will trigger a mac_link_down() method call.)
+ * It may also be called after phylink_suspend() if the MAC cannot resume
+ * and the network device must be closed instead.
  */
 void phylink_stop(struct phylink *pl)
 {
 	ASSERT_RTNL();
 
+	/* phylink_suspend() already stops the link without MAC WoL. */
+	if (test_bit(PHYLINK_DISABLE_STOPPED, &pl->phylink_disable_state))
+		return;
+
 	if (pl->sfp_bus)
 		sfp_upstream_stop(pl->sfp_bus);
 	if (pl->phydev)
@@ -2512,6 +2518,16 @@ void phylink_stop(struct phylink *pl)
 
 	phylink_run_resolve_and_disable(pl, PHYLINK_DISABLE_STOPPED);
 
+	if (test_bit(PHYLINK_DISABLE_MAC_WOL, &pl->phylink_disable_state)) {
+		/* Finish the link-down deferred by MAC WoL, without restarting. */
+		flush_work(&pl->resolve);
+		mutex_lock(&pl->state_mutex);
+		if (pl->suspend_link_up)
+			phylink_link_down(pl);
+		__clear_bit(PHYLINK_DISABLE_MAC_WOL, &pl->phylink_disable_state);
+		mutex_unlock(&pl->state_mutex);
+	}
+
 	pl->pcs_state = PCS_STATE_DOWN;
 
 	phylink_pcs_disable(pl->pcs);

-- 
2.53.0