RE: [PATCH 2/2] e1000e: Fix link check race condition

From: netdev-owner@vger.kernel.org [mailto:netdev-
owner@vger.kernel.org] On Behalf Of Benjamin Poirier
Sent: Monday, March 5, 2018 5:56 PM
To: Kirsher, Jeffrey T <redacted>
Cc: Alexander Duyck <redacted>; Lennart Sorensen
[off-list ref]; intel-wired-lan@lists.osuosl.org;
netdev@vger.kernel.org; linux-kernel@vger.kernel.org
Subject: [PATCH 2/2] e1000e: Fix link check race condition

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 <redacted>
Signed-off-by: Benjamin Poirier <redacted>
---
 drivers/net/ethernet/intel/e1000e/ich8lan.c | 31 ++++++++++++++++-------
------
 drivers/net/ethernet/intel/e1000e/mac.c     | 14 ++++++-------
 2 files changed, 24 insertions(+), 21 deletions(-)

Tested-by: Aaron Brown <redacted>