Patch "net: mdio-mux: Handle -EPROBE_DEFER correctly" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: mdio-mux: Handle -EPROBE_DEFER correctly

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-mdio-mux-handle-eprobe_defer-correctly.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ff54e9bb2afcd37e8c23d0d799c3551f5421572a
Author: Saravana Kannan <saravanak@xxxxxxxxxx>
Date:   Tue Aug 17 20:38:03 2021 -0700

    net: mdio-mux: Handle -EPROBE_DEFER correctly
    
    [ Upstream commit 7bd0cef5dac685f09ef8b0b2a7748ff42d284dc7 ]
    
    When registering mdiobus children, if we get an -EPROBE_DEFER, we shouldn't
    ignore it and continue registering the rest of the mdiobus children. This
    would permanently prevent the deferring child mdiobus from working instead
    of reattempting it in the future. So, if a child mdiobus needs to be
    reattempted in the future, defer the entire mdio-mux initialization.
    
    This fixes the issue where PHYs sitting under the mdio-mux aren't
    initialized correctly if the PHY's interrupt controller is not yet ready
    when the mdio-mux is being probed. Additional context in the link below.
    
    Fixes: 0ca2997d1452 ("netdev/of/phy: Add MDIO bus multiplexer support.")
    Link: https://lore.kernel.org/lkml/CAGETcx95kHrv8wA-O+-JtfH7H9biJEGJtijuPVN0V5dUKUAB3A@xxxxxxxxxxxxxx/#t
    Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
    Reviewed-by: Andrew Lunn <andrew@xxxxxxx>
    Acked-by: Marc Zyngier <maz@xxxxxxxxxx>
    Tested-by: Marc Zyngier <maz@xxxxxxxxxx>
    Acked-by: Kevin Hilman <khilman@xxxxxxxxxxxx>
    Tested-by: Kevin Hilman <khilman@xxxxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/mdio/mdio-mux.c b/drivers/net/mdio/mdio-mux.c
index c96ef3b3fa3a..ccb3ee704eb1 100644
--- a/drivers/net/mdio/mdio-mux.c
+++ b/drivers/net/mdio/mdio-mux.c
@@ -175,11 +175,15 @@ int mdio_mux_init(struct device *dev,
 		cb->mii_bus->write = mdio_mux_write;
 		r = of_mdiobus_register(cb->mii_bus, child_bus_node);
 		if (r) {
+			mdiobus_free(cb->mii_bus);
+			if (r == -EPROBE_DEFER) {
+				ret_val = r;
+				goto err_loop;
+			}
+			devm_kfree(dev, cb);
 			dev_err(dev,
 				"Error: Failed to register MDIO bus for child %pOF\n",
 				child_bus_node);
-			mdiobus_free(cb->mii_bus);
-			devm_kfree(dev, cb);
 		} else {
 			cb->next = pb->children;
 			pb->children = cb;