net: phylink: avoid resolving link state too early

commit 87454b6edc1b0143fdb3d9853285477e95af74a4 upstream.

During testing on Armada 388 platforms, it was found with a certain
module configuration that it was possible to trigger a kernel oops
during the module load process, caused by the phylink resolver being
triggered for a currently disabled interface.

This problem was introduced by changing the way the SFP registration
works, which now can result in the sfp link down notification being
called during phylink_create().

Fixes: b5bfc21af5cb ("net: sfp: do not probe SFP module before we're attached")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 70f3f90..2787e8b 100644 (file)
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -502,6 +502,17 @@ static void phylink_run_resolve(struct phylink *pl)
                queue_work(system_power_efficient_wq, &pl->resolve);
 }
 
+static void phylink_run_resolve_and_disable(struct phylink *pl, int bit)
+{
+       unsigned long state = pl->phylink_disable_state;
+
+       set_bit(bit, &pl->phylink_disable_state);
+       if (state == 0) {
+               queue_work(system_power_efficient_wq, &pl->resolve);
+               flush_work(&pl->resolve);
+       }
+}
+
 static void phylink_fixed_poll(struct timer_list *t)
 {
        struct phylink *pl = container_of(t, struct phylink, link_poll);
@@ -955,9 +966,7 @@ void phylink_stop(struct phylink *pl)
        if (pl->link_an_mode == MLO_AN_FIXED && !IS_ERR(pl->link_gpio))
                del_timer_sync(&pl->link_poll);
 
-       set_bit(PHYLINK_DISABLE_STOPPED, &pl->phylink_disable_state);
-       queue_work(system_power_efficient_wq, &pl->resolve);
-       flush_work(&pl->resolve);
+       phylink_run_resolve_and_disable(pl, PHYLINK_DISABLE_STOPPED);
 }
 EXPORT_SYMBOL_GPL(phylink_stop);
 
@@ -1664,9 +1673,7 @@ static void phylink_sfp_link_down(void *upstream)
 
        ASSERT_RTNL();
 
-       set_bit(PHYLINK_DISABLE_LINK, &pl->phylink_disable_state);
-       queue_work(system_power_efficient_wq, &pl->resolve);
-       flush_work(&pl->resolve);
+       phylink_run_resolve_and_disable(pl, PHYLINK_DISABLE_LINK);
 }
 
 static void phylink_sfp_link_up(void *upstream)