netdev - [REPORT] net: e1000e: possible data races

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Date:   Wed, 3 Oct 2018 21:18:41 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     jeffrey.t.kirsher@...el.com, davem@...emloft.net
Cc:     intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [REPORT] net: e1000e: possible data races

CPU0:
e1000e_get_stats64
     line 5944: spin_lock()
     e1000e_update_stats
         line 4949: hw->mac.tx_packet_delta = er32(TPT); [WRITE]

CPU1:
e1000_watchdog_task
     e1000e_update_adaptive
         line 1762: mac->tx_packet_delta [READ]
         line 1763: mac->tx_packet_delta [READ]
         line 1776: mac->tx_packet_delta [READ]

As for mac->tx_packet_delta, the WRITE operation in CPU0 is performed
with holding a spinlock, but the READ operations in CPU1 are performed
without holding this spinlock, so there may exist data races.

These possible races are detected by a runtime testing.
I do not find a good way to fix these races, so I only report them.

Best wishes,
Jia-Ju Bai