-----Original Message-----
From: Mohammed Gamal [mailto:mgamal@redhat.com]
Sent: Tuesday, January 23, 2018 4:34 AM
To: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org; devel@linuxdriverproject.org; KY
Srinivasan [off-list ref]; Haiyang Zhang [off-list ref];
Stephen Hemminger [off-list ref]; vkuznets@redhat.com;
cavery@redhat.com; otubo@redhat.com; Mohammed Gamal
[off-list ref]
Subject: [RFC PATCH 0/2] hv_netvsc: Fix shutdown regression on Win2012
hosts

Commit 0cf737808ae7 ("hv_netvsc: netvsc_teardown_gpadl() split")
introduced a regression that caused VMs not to shutdown after
netvsc_device_remove() is called. This is caused by GPADL teardown
sequence change, and while that was necessary to fix issues with Win2016
hosts, it did introduce a regression for earlier versions.

Prior to commit 0cf737808 the call sequence in netvsc_device_remove() was
as follows (as implemented in netvsc_destroy_buf()):
1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
2- Teardown receive buffer GPADL
3- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
4- Teardown send buffer GPADL
5- Close vmbus

This didn't work for WS2016 hosts. Commit 0cf737808 split
netvsc_destroy_buf() into two functions and rearranged the order as follows
1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
2- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
3- Close vmbus
4- Teardown receive buffer GPADL
5- Teardown send buffer GPADL

That worked well for WS2016 hosts, but for WS2012 hosts it prevented VMs
from shutting down.

This patch series works around this problem. The first patch splits
netvsc_revoke_buf() and netvsc_teardown_gpadl() into two finer grained
functions for tearing down send and receive buffers individally. The second
patch uses the finer grained functions to implement the teardown sequence
according to the host's version. We keep the behavior introduced in
0cf737808ae7 for Windows
2016 hosts, while we re-introduce the old sequence for earlier verions.

Mohammed Gamal (2):
  hv_netvsc: Split netvsc_revoke_buf() and netvsc_teardown_gpadl()
  hv_netvsc: Change GPADL teardown order according to Hyper-V version

 drivers/net/hyperv/netvsc.c | 50
+++++++++++++++++++++++++++++++++++++--------
 1 file changed, 42 insertions(+), 8 deletions(-)

Thank you for the patches. We are testing them internally.

- Haiyang