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Commit 53801d8f authored by Benjamin Poirier's avatar Benjamin Poirier Committed by Greg Kroah-Hartman
Browse files

e1000e: Separate signaling for link check/link up 



commit 19110cfbb34d4af0cdfe14cd243f3b09dc95b013 upstream.

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: default avatarLennart Sorensen <lsorense@csclub.uwaterloo.ca>
Signed-off-by: default avatarBenjamin Poirier <bpoirier@suse.com>
Tested-by: default avatarAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: default avatarAmit Pundir <amit.pundir@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c493ba2d

drivers/net/ethernet/intel/e1000e/mac.c

+8 −3
Original line number Diff line number Diff line
@@ -410,6 +410,9 @@ void e1000e_clear_hw_cntrs_base(struct e1000_hw *hw) 
 *  Checks to see of the link status of the hardware has changed.  If a

 *  change in link status has been detected, then we read the PHY registers

 *  to get the current speed/duplex if link exists.

 *

 *  Returns a negative error code (-E1000_ERR_*) or 0 (link down) or 1 (link

 *  up).

 **/

s32 e1000e_check_for_copper_link(struct e1000_hw *hw)

{
@@ -423,7 +426,7 @@ s32 e1000e_check_for_copper_link(struct e1000_hw *hw) 
	 * Change or Rx Sequence Error interrupt.

	 */

	if (!mac->get_link_status)

		return 0;

		return 1;



	/* First we want to see if the MII Status Register reports

	 * link.  If so, then we want to get the current speed/duplex
@@ -461,12 +464,14 @@ s32 e1000e_check_for_copper_link(struct e1000_hw *hw) 
	 * different link partner.

	 */

	ret_val = e1000e_config_fc_after_link_up(hw);

	if (ret_val)

	if (ret_val) {

		e_dbg("Error configuring flow control\n");



		return ret_val;

	}



	return 1;

}



/**

 *  e1000e_check_for_fiber_link - Check for link (Fiber)

 *  @hw: pointer to the HW structure

drivers/net/ethernet/intel/e1000e/netdev.c

+1 −1
Original line number Diff line number Diff line
@@ -4844,7 +4844,7 @@ 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;

		}