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e1000e: Separate signaling for link check/link up

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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>
This commit is contained in:
Benjamin Poirier 2017-07-21 11:36:26 -07:00 • committed by Jeff Kirsher
parent d3509f8bc7
commit 19110cfbb3
2 changed files with 9 additions and 4 deletions
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11
drivers/net/ethernet/intel/e1000e/mac.c
View file

@ -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 * 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 * change in link status has been detected, then we read the PHY registers
* to get the current speed/duplex if link exists. * 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) 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. * Change or Rx Sequence Error interrupt.
*/ */
if (!mac->get_link_status) if (!mac->get_link_status)
return 0; return 1;
/* First we want to see if the MII Status Register reports /* First we want to see if the MII Status Register reports
* link. If so, then we want to get the current speed/duplex * link. If so, then we want to get the current speed/duplex
@ -461,10 +464,12 @@ s32 e1000e_check_for_copper_link(struct e1000_hw *hw)
* different link partner. * different link partner.
*/ */
ret_val = e1000e_config_fc_after_link_up(hw); ret_val = e1000e_config_fc_after_link_up(hw);
if (ret_val) if (ret_val) {
e_dbg("Error configuring flow control\n"); e_dbg("Error configuring flow control\n");
return ret_val;
}
return ret_val; return 1;
} }
/** /**

2
drivers/net/ethernet/intel/e1000e/netdev.c
View file

@ -5081,7 +5081,7 @@ static bool e1000e_has_link(struct e1000_adapter *adapter)
case e1000_media_type_copper: case e1000_media_type_copper:
if (hw->mac.get_link_status) { if (hw->mac.get_link_status) {
ret_val = hw->mac.ops.check_for_link(hw); ret_val = hw->mac.ops.check_for_link(hw);
link_active = !hw->mac.get_link_status; link_active = ret_val > 0;
} else { } else {
link_active = true; link_active = true;
} }