Subject: [PATCH 5/6] Revert "e1000e: Separate signaling for link check/link up"

From: Benjamin Poirier <[email-masked]>
Date: Tue, 6 Mar 2018 10:55:52 +0900

commit 3016e0a0c91246e55418825ba9aae271be267522 upstream.

This reverts commit 19110cfbb34d4af0cdfe14cd243f3b09dc95b013.
This reverts commit 4110e02eb45ea447ec6f5459c9934de0a273fb91.
This reverts commit d3604515c9eda464a92e8e67aae82dfe07fe3c98.

Commit 19110cfbb34d ("e1000e: Separate signaling for link check/link up")
changed what happens to the link status when there is an error which
happens after "get_link_status = false" in the copper check_for_link
callbacks. Previously, such an error would be ignored and the link
considered up. After that commit, any error implies that the link is down.

Revert commit 19110cfbb34d ("e1000e: Separate signaling for link check/link
up") and its followups. After reverting, the race condition described in
the log of commit 19110cfbb34d is reintroduced. It may still be triggered
by LSC events but this should keep the link down in case the link is
electrically unstable, as discussed. The race may no longer be
triggered by RXO events because commit 4aea7a5c5e94 ("e1000e: Avoid
receiver overrun interrupt bursts") restored reading icr in the Other
handler.

Link: https://lkml.org/lkml/2018/3/1/789
Signed-off-by: Benjamin Poirier <[email-masked]>
Acked-by: Alexander Duyck <[email-masked]>
Tested-by: Aaron Brown <[email-masked]>
Signed-off-by: Jeff Kirsher <[email-masked]>
Cc: Yanhui He <[email-masked]>
Signed-off-by: Ben Hutchings <[email-masked]>
---
 drivers/net/ethernet/intel/e1000e/ich8lan.c | 13 ++++---------
 drivers/net/ethernet/intel/e1000e/mac.c     | 13 ++++---------
 drivers/net/ethernet/intel/e1000e/netdev.c  |  2 +-
 3 files changed, 9 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c
index 7ddac956ffb5..f3aaca743ea3 100644
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
@@ -1364,9 +1364,6 @@ static s32 e1000_disable_ulp_lpt_lp(struct e1000_hw *hw, bool force)
  *  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).
  **/
 static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
 {
@@ -1382,7 +1379,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
 	 * Change or Rx Sequence Error interrupt.
 	 */
 	if (!mac->get_link_status)
-		return 1;
+		return 0;
 
 	/* First we want to see if the MII Status Register reports
 	 * link.  If so, then we want to get the current speed/duplex
@@ -1600,7 +1597,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
 	 * we have already determined whether we have link or not.
 	 */
 	if (!mac->autoneg)
-		return 1;
+		return -E1000_ERR_CONFIG;
 
 	/* Auto-Neg is enabled.  Auto Speed Detection takes care
 	 * of MAC speed/duplex configuration.  So we only need to
@@ -1614,12 +1611,10 @@ static s32 e1000_check_for_copper_link_ich8lan(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;
+	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 db735644b312..b322011ec282 100644
--- a/drivers/net/ethernet/intel/e1000e/mac.c
+++ b/drivers/net/ethernet/intel/e1000e/mac.c
@@ -410,9 +410,6 @@ 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)
 {
@@ -426,7 +423,7 @@ s32 e1000e_check_for_copper_link(struct e1000_hw *hw)
 	 * Change or Rx Sequence Error interrupt.
 	 */
 	if (!mac->get_link_status)
-		return 1;
+		return 0;
 
 	/* First we want to see if the MII Status Register reports
 	 * link.  If so, then we want to get the current speed/duplex
@@ -450,7 +447,7 @@ s32 e1000e_check_for_copper_link(struct e1000_hw *hw)
 	 * we have already determined whether we have link or not.
 	 */
 	if (!mac->autoneg)
-		return 1;
+		return -E1000_ERR_CONFIG;
 
 	/* Auto-Neg is enabled.  Auto Speed Detection takes care
 	 * of MAC speed/duplex configuration.  So we only need to
@@ -464,12 +461,10 @@ 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;
+	return ret_val;
 }
 
 /**
diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index dfde22e9a8b6..6855b3380a83 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -5074,7 +5074,7 @@ 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 = ret_val > 0;
+			link_active = !hw->mac.get_link_status;
 		} else {
 			link_active = true;
 		}