RE: [PATCH 2/2] e1000e: Fix link check race condition

[Brown, Aaron F]

> From: netdev-ow...@vger.kernel.org [mailto:netdev-
> ow...@vger.kernel.org] On Behalf Of Benjamin Poirier
> Sent: Monday, March 5, 2018 5:56 PM
> To: Kirsher, Jeffrey T <jeffrey.t.kirs...@intel.com>
> Cc: Alexander Duyck <alexander.du...@gmail.com>; Lennart Sorensen
> <lsore...@csclub.uwaterloo.ca>; intel-wired-...@lists.osuosl.org;
> netdev@vger.kernel.org; linux-ker...@vger.kernel.org
> Subject: [PATCH 2/2] e1000e: Fix link check race condition
> 
> 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 = 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.du...@gmail.com>
> Signed-off-by: Benjamin Poirier <bpoir...@suse.com>
> ---
>  drivers/net/ethernet/intel/e1000e/ich8lan.c | 31 ---
> --
>  drivers/net/ethernet/intel/e1000e/mac.c | 14 ++---
>  2 files changed, 24 insertions(+), 21 deletions(-)

Tested-by: Aaron Brown <aaron.f.br...@intel.com>

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

[Alexander Duyck]

On Mon, Mar 5, 2018 at 5:55 PM, Benjamin Poirier  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 = 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 
> Signed-off-by: Benjamin Poirier 

Looks good. Thanks.

Acked-by: Alexander Duyck 

[PATCH 2/2] e1000e: Fix link check race condition

[Benjamin Poirier]

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 = 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 
Signed-off-by: Benjamin Poirier 
---
 drivers/net/ethernet/intel/e1000e/ich8lan.c | 31 -
 drivers/net/ethernet/intel/e1000e/mac.c | 14 ++---
 2 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c 
b/drivers/net/ethernet/intel/e1000e/ich8lan.c
index d6d4ed7acf03..1dddfb7b2de6 100644
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
@@ -1383,6 +1383,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct 
e1000_hw *hw)
 */
if (!mac->get_link_status)
return 0;
+   mac->get_link_status = false;
 
/* First we want to see if the MII Status Register reports
 * link.  If so, then we want to get the current speed/duplex
@@ -1390,12 +1391,12 @@ static s32 e1000_check_for_copper_link_ich8lan(struct 
e1000_hw *hw)
 */
ret_val = e1000e_phy_has_link_generic(hw, 1, 0, );
if (ret_val)
-   return ret_val;
+   goto out;
 
if (hw->mac.type == e1000_pchlan) {
ret_val = e1000_k1_gig_workaround_hv(hw, link);
if (ret_val)
-   return ret_val;
+   goto out;
}
 
/* When connected at 10Mbps half-duplex, some parts are excessively
@@ -1428,7 +1429,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct 
e1000_hw *hw)
 
ret_val = hw->phy.ops.acquire(hw);
if (ret_val)
-   return ret_val;
+   goto out;
 
if (hw->mac.type == e1000_pch2lan)
emi_addr = I82579_RX_CONFIG;
@@ -1450,7 +1451,7 @@ static s32 e1000_check_for_copper_link_ich8lan(struct 
e1000_hw *hw)
hw->phy.ops.release(hw);
 
if (ret_val)
-   return ret_val;
+   goto out;
 
if (hw->mac.type >= e1000_pch_spt) {
u16 data;
@@ -1459,14 +1460,14 @@ static s32 e1000_check_for_copper_link_ich8lan(struct 
e1000_hw *hw)
if (speed == SPEED_1000) {
ret_val = hw->phy.ops.acquire(hw);
if (ret_val)
-   return ret_val;
+   goto out;
 
ret_val = e1e_rphy_locked(hw,
  PHY_REG(776, 20),
  );
if (ret_val) {
hw->phy.ops.release(hw);
-   return ret_val;
+   goto out;
}
 
ptr_gap = (data & (0x3FF << 2)) >> 2;
@@ -1480,18 +1481,18 @@ static s32 e1000_check_for_copper_link_ich8lan(struct 
e1000_hw *hw)
}
hw->phy.ops.release(hw);
if (ret_val)
-   return ret_val;
+   goto out;
} else {
ret_val = hw->phy.ops.acquire(hw);
if (ret_val)
-   return ret_val;
+   goto out;
 
ret_val = e1e_wphy_locked(hw,
  PHY_REG(776, 20),
  0xC023);
hw->phy.ops.release(hw);
if (ret_val)
-   return ret_val;
+