1 From patchwork Fri Jul 21 18:36:26 2017
2 Content-Type: text/plain; charset="utf-8"
4 Content-Transfer-Encoding: 7bit
5 Subject: [4/5] e1000e: Separate signaling for link check/link up
6 From: Benjamin Poirier <bpoirier@suse.com>
7 X-Patchwork-Id: 9857491
8 Message-Id: <20170721183627.13373-4-bpoirier@suse.com>
9 To: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
10 Cc: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>,
11 intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
12 linux-kernel@vger.kernel.org
13 Date: Fri, 21 Jul 2017 11:36:26 -0700
15 Lennart reported the following race condition:
19 \ hw->mac.ops.check_for_link() === e1000e_check_for_copper_link
21 mac->get_link_status = false;
25 hw->mac.get_link_status = true;
27 link_active = !hw->mac.get_link_status
28 /* link_active is false, wrongly */
30 This problem arises because the single flag get_link_status is used to
31 signal two different states: link status needs checking and link status is
34 Avoid the problem by using the return value of .check_for_link to signal
35 the link status to e1000e_has_link().
37 Reported-by: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>
38 Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
40 drivers/net/ethernet/intel/e1000e/mac.c | 11 ++++++++---
41 drivers/net/ethernet/intel/e1000e/netdev.c | 2 +-
42 2 files changed, 9 insertions(+), 4 deletions(-)
44 --- a/drivers/net/ethernet/intel/e1000e/mac.c
45 +++ b/drivers/net/ethernet/intel/e1000e/mac.c
46 @@ -410,6 +410,9 @@ void e1000e_clear_hw_cntrs_base(struct e
47 * Checks to see of the link status of the hardware has changed. If a
48 * change in link status has been detected, then we read the PHY registers
49 * to get the current speed/duplex if link exists.
51 + * Returns a negative error code (-E1000_ERR_*) or 0 (link down) or 1 (link
54 s32 e1000e_check_for_copper_link(struct e1000_hw *hw)
56 @@ -423,7 +426,7 @@ s32 e1000e_check_for_copper_link(struct
57 * Change or Rx Sequence Error interrupt.
59 if (!mac->get_link_status)
63 /* First we want to see if the MII Status Register reports
64 * link. If so, then we want to get the current speed/duplex
65 @@ -461,10 +464,12 @@ s32 e1000e_check_for_copper_link(struct
66 * different link partner.
68 ret_val = e1000e_config_fc_after_link_up(hw);
71 e_dbg("Error configuring flow control\n");
80 --- a/drivers/net/ethernet/intel/e1000e/netdev.c
81 +++ b/drivers/net/ethernet/intel/e1000e/netdev.c
82 @@ -5056,7 +5056,7 @@ static bool e1000e_has_link(struct e1000
83 case e1000_media_type_copper:
84 if (hw->mac.get_link_status) {
85 ret_val = hw->mac.ops.check_for_link(hw);
86 - link_active = !hw->mac.get_link_status;
87 + link_active = ret_val > 0;