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SubjectRe: [PATCH 4/5] e1000e: Separate signaling for link check/link up
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On Fri, Jul 21, 2017 at 11:36:26AM -0700, Benjamin Poirier wrote:
> Lennart reported the following race condition:
>
> \ e1000_watchdog_task
> \ e1000e_has_link
> \ hw->mac.ops.check_for_link() === e1000e_check_for_copper_link
> /* link is up */
> mac->get_link_status = false;
>
> /* interrupt */
> \ e1000_msix_other
> hw->mac.get_link_status = true;
>
> link_active = !hw->mac.get_link_status
> /* link_active is false, wrongly */
>
> This problem arises because the single flag get_link_status is used to
> signal two different states: link status needs checking and link status is
> down.
>
> Avoid the problem by using the return value of .check_for_link to signal
> the link status to e1000e_has_link().
>
> Reported-by: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>
> Signed-off-by: Benjamin Poirier <bpoirier@suse.com>

This too seems potentially -stable worthy, although with patch 5, the
problem becomes much much less likely to occur.

--
Len Sorensen

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