Re: igb: do not re-init SR-IOV during probe

[Daniel J Blueman]

It would be great if the patch "igb: do not re-init SR-IOV during 
probe" [1] can be backported from 4.3-rc to stable kernels, since it 
fixes the regression introduced by "igb: do a reset on SR-IOV re-init 
if device is down" [2].

The regression was introduced in 3.16 and can isolate the IPMI 
interface on servers with 82576 NICs if using shared mode (high 
impact), around 0.5% of times booted.

Many thanks!
 Daniel

-- [1]

commit 6423fc34160939142d72ffeaa2db6408317f54df
Author: Stefan Assmann <sassmann@xxxxxxxxx>
Date:   Fri Jul 10 15:01:12 2015 +0200

   igb: do not re-init SR-IOV during probe

   During driver probing the following code path is triggered.
   igb_probe
   ->igb_sw_init
     ->igb_probe_vfs
       ->igb_pci_enable_sriov
         ->igb_sriov_reinit

   Doing the SR-IOV re-init is not necessary during probing since we're
   starting from scratch. Here we can call igb_enable_sriov() right 
away.

   Running igb_sriov_reinit() during igb_probe() also seems to cause
   occasional packet loss on some onboard 82576 NICs. Reproduced on
   Dell and HP servers with onboard 82576 NICs.
   Example:
   Intel Corporation 82576 Gigabit Network Connection [8086:10c9] (rev 
01)
   Subsystem: Dell Device [1028:0481]

   Signed-off-by: Stefan Assmann <sassmann@xxxxxxxxx>
   Tested-by: Aaron Brown <aaron.f.brown@xxxxxxxxx>
   Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>

-- [2]

commit 76252723e88681628a3dbb9c09c963e095476f73
Author: Stefan Assmann <sassmann@xxxxxxxxx>
Date:   Thu Jul 10 03:29:39 2014 -0700

  igb: do a reset on SR-IOV re-init if device is down

  To properly re-initialize SR-IOV it is necessary to reset the device
  even if it is already down. Not doing this may result in Tx unit 
hangs.

  Cc: stable <stable@xxxxxxxxxxxxxxx>
  Signed-off-by: Stefan Assmann <sassmann@xxxxxxxxx>
  Tested-by: Aaron Brown <aaron.f.brown@xxxxxxxxx>
  Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
  Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>


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