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From patchwork Fri Jul 21 18:36:26 2017
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: [4/5] e1000e: Separate signaling for link check/link up
From: Benjamin Poirier <bpoirier@suse.com>
X-Patchwork-Id: 9857491
Message-Id: <20170721183627.13373-4-bpoirier@suse.com>
To: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>,
intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Date: Fri, 21 Jul 2017 11:36:26 -0700
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>
---
drivers/net/ethernet/intel/e1000e/mac.c | 11 ++++++++---
drivers/net/ethernet/intel/e1000e/netdev.c | 2 +-
2 files changed, 9 insertions(+), 4 deletions(-)
--- a/drivers/net/ethernet/intel/e1000e/mac.c
+++ b/drivers/net/ethernet/intel/e1000e/mac.c
@@ -410,6 +410,9 @@ void e1000e_clear_hw_cntrs_base(struct e
* Checks to see of the link status of the hardware has changed. If a
* change in link status has been detected, then we read the PHY registers
* to get the current speed/duplex if link exists.
+ *
+ * Returns a negative error code (-E1000_ERR_*) or 0 (link down) or 1 (link
+ * up).
**/
s32 e1000e_check_for_copper_link(struct e1000_hw *hw)
{
@@ -423,7 +426,7 @@ s32 e1000e_check_for_copper_link(struct
* Change or Rx Sequence Error interrupt.
*/
if (!mac->get_link_status)
- return 0;
+ return 1;
/* First we want to see if the MII Status Register reports
* link. If so, then we want to get the current speed/duplex
@@ -461,10 +464,12 @@ s32 e1000e_check_for_copper_link(struct
* different link partner.
*/
ret_val = e1000e_config_fc_after_link_up(hw);
- if (ret_val)
+ if (ret_val) {
e_dbg("Error configuring flow control\n");
+ return ret_val;
+ }
- return ret_val;
+ return 1;
}
/**
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -5056,7 +5056,7 @@ static bool e1000e_has_link(struct e1000
case e1000_media_type_copper:
if (hw->mac.get_link_status) {
ret_val = hw->mac.ops.check_for_link(hw);
- link_active = !hw->mac.get_link_status;
+ link_active = ret_val > 0;
} else {
link_active = true;
}
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