e1000e: Separate signaling for link check/link up

Lennart reported the following race condition:

\ e1000_watchdog_task
    \ e1000e_has_link
        \ hw->mac.ops.check_for_link() === e1000e_check_for_copper_link
            /* link is up */
            mac->get_link_status = false;

                            /* interrupt */
                            \ e1000_msix_other
                                hw->mac.get_link_status = true;

        link_active = !hw->mac.get_link_status
        /* link_active is false, wrongly */

This problem arises because the single flag get_link_status is used to
signal two different states: link status needs checking and link status is
down.

Avoid the problem by using the return value of .check_for_link to signal
the link status to e1000e_has_link().

Reported-by: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>
Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index a740de6a30b0..0a5f95ab0d3c 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -5081,7 +5081,7 @@ static bool e1000e_has_link(struct e1000_adapter *adapter)
 	case e1000_media_type_copper:
 		if (hw->mac.get_link_status) {
 			ret_val = hw->mac.ops.check_for_link(hw);
-			link_active = !hw->mac.get_link_status;
+			link_active = ret_val > 0;
 		} else {
 			link_active = true;
 		}