e1000e: Fix link check race condition

commit e2710dbf0dc1e37d85368e2404049dadda848d5a upstream.

Alex reported the following race condition:

/* link goes up... interrupt... schedule watchdog */
\ e1000_watchdog_task
	\ e1000e_has_link
		\ hw->mac.ops.check_for_link() === e1000e_check_for_copper_link
			\ e1000e_phy_has_link_generic(..., &link)
				link = true

					 /* link goes down... interrupt */
					 \ e1000_msix_other
						 hw->mac.get_link_status = true

			/* link is up */
			mac->get_link_status = false

		link_active = true
		/* link_active is true, wrongly, and stays so because
		 * get_link_status is false */

Avoid this problem by making sure that we don't set get_link_status = false
after having checked the link.

It seems this problem has been present since the introduction of e1000e.

Link: https://lkml.org/lkml/2018/1/29/338
Reported-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c
index d6d4ed7..1dddfb7 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
@@ -1383,6 +1383,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
         */
        if (!mac->get_link_status)
                return 0;
+       mac->get_link_status = false;
 
        /* First we want to see if the MII Status Register reports
         * link.  If so, then we want to get the current speed/duplex
@@ -1390,12 +1391,12 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
         */
        ret_val = e1000e_phy_has_link_generic(hw, 1, 0, &link);
        if (ret_val)
-               return ret_val;
+               goto out;
 
        if (hw->mac.type == e1000_pchlan) {
                ret_val = e1000_k1_gig_workaround_hv(hw, link);
                if (ret_val)
-                       return ret_val;
+                       goto out;
        }
 
        /* When connected at 10Mbps half-duplex, some parts are excessively
@@ -1428,7 +1429,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
 
                ret_val = hw->phy.ops.acquire(hw);
                if (ret_val)
-                       return ret_val;
+                       goto out;
 
                if (hw->mac.type == e1000_pch2lan)
                        emi_addr = I82579_RX_CONFIG;
@@ -1450,7 +1451,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
                hw->phy.ops.release(hw);
 
                if (ret_val)
-                       return ret_val;
+                       goto out;
 
                if (hw->mac.type >= e1000_pch_spt) {
                        u16 data;
@@ -1459,14 +1460,14 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
                        if (speed == SPEED_1000) {
                                ret_val = hw->phy.ops.acquire(hw);
                                if (ret_val)
-                                       return ret_val;
+                                       goto out;
 
                                ret_val = e1e_rphy_locked(hw,
                                                          PHY_REG(776, 20),
                                                          &data);
                                if (ret_val) {
                                        hw->phy.ops.release(hw);
-                                       return ret_val;
+                                       goto out;
                                }
 
                                ptr_gap = (data & (0x3FF << 2)) >> 2;
@@ -1480,18 +1481,18 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
                                }
                                hw->phy.ops.release(hw);
                                if (ret_val)
-                                       return ret_val;
+                                       goto out;
                        } else {
                                ret_val = hw->phy.ops.acquire(hw);
                                if (ret_val)
-                                       return ret_val;
+                                       goto out;
 
                                ret_val = e1e_wphy_locked(hw,
                                                          PHY_REG(776, 20),
                                                          0xC023);
                                hw->phy.ops.release(hw);
                                if (ret_val)
-                                       return ret_val;
+                                       goto out;
 
                        }
                }
@@ -1518,7 +1519,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
            (hw->adapter->pdev->device == E1000_DEV_ID_PCH_I218_V3)) {
                ret_val = e1000_k1_workaround_lpt_lp(hw, link);
                if (ret_val)
-                       return ret_val;
+                       goto out;
        }
        if (hw->mac.type >= e1000_pch_lpt) {
                /* Set platform power management values for
@@ -1526,7 +1527,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
                 */
                ret_val = e1000_platform_pm_pch_lpt(hw, link);
                if (ret_val)
-                       return ret_val;
+                       goto out;
        }
 
        /* Clear link partner's EEE ability */
@@ -1549,9 +1550,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
        }
 
        if (!link)
-               return 0;       /* No link detected */
-
-       mac->get_link_status = false;
+               goto out;
 
        switch (hw->mac.type) {
        case e1000_pch2lan:
@@ -1617,6 +1616,10 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
                e_dbg("Error configuring flow control\n");
 
        return ret_val;
+
+out:
+       mac->get_link_status = true;
+       return ret_val;
 }
 
 static s32 e1000_get_variants_ich8lan(struct e1000_adapter *adapter)

diff --git a/drivers/net/ethernet/intel/e1000e/mac.c b/drivers/net/ethernet/intel/e1000e/mac.c
index b322011..5bdc3a2 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/mac.c
+++ b/drivers/net/ethernet/intel/e1000e/mac.c
@@ -424,19 +424,15 @@ s32 e1000e_check_for_copper_link(struct e1000_hw *hw)
         */
        if (!mac->get_link_status)
                return 0;
+       mac->get_link_status = false;
 
        /* First we want to see if the MII Status Register reports
         * link.  If so, then we want to get the current speed/duplex
         * of the PHY.
         */
        ret_val = e1000e_phy_has_link_generic(hw, 1, 0, &link);
-       if (ret_val)
-               return ret_val;
-
-       if (!link)
-               return 0;       /* No link detected */
-
-       mac->get_link_status = false;
+       if (ret_val || !link)
+               goto out;
 
        /* Check if there was DownShift, must be checked
         * immediately after link-up
@@ -465,6 +461,10 @@ s32 e1000e_check_for_copper_link(struct e1000_hw *hw)
                e_dbg("Error configuring flow control\n");
 
        return ret_val;
+
+out:
+       mac->get_link_status = true;
+       return ret_val;
 }
 
 /**