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SubjectRE: [PATCH 2/2] e1000e: Fix link check race condition
Date
> 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 <jeffrey.t.kirsher@intel.com>
> Cc: Alexander Duyck <alexander.duyck@gmail.com>; Lennart Sorensen
> <lsorense@csclub.uwaterloo.ca>; 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 <alexander.duyck@gmail.com>
> Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
> ---
> 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 <aaron.f.brown@intel.com>

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