linux-kernel - Re: [PATCH 2/2] e1000e: Fix link check race condition

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Date:   Tue, 6 Mar 2018 06:53:59 -0800
From:   Alexander Duyck <alexander.duyck@...il.com>
To:     Benjamin Poirier <bpoirier@...e.com>
Cc:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Lennart Sorensen <lsorense@...lub.uwaterloo.ca>,
        intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
        Netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] e1000e: Fix link check race condition

On Mon, Mar 5, 2018 at 5:55 PM, Benjamin Poirier <bpoirier@...e.com> wrote:
> 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@...il.com>
> Signed-off-by: Benjamin Poirier <bpoirier@...e.com>

Looks good. Thanks.

Acked-by: Alexander Duyck <alexander.h.duyck@...el.com>