[SRU][Xenial][Yakkety][PATCH 1/2] PCI: hv: Report resources release after stopping the bus

[Joseph Salisbury]

From: Vitaly Kuznetsov <vkuznets at redhat.com>

BugLink: http://bugs.launchpad.net/bugs/1581243

Kernel hang is observed when pci-hyperv module is release with device
drivers still attached.  E.g., when I do 'rmmod pci_hyperv' with BCM5720
device pass-through-ed (tg3 module) I see the following:

 NMI watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [rmmod:2104]
 ...
 Call Trace:
  [<ffffffffa0641487>] tg3_read_mem+0x87/0x100 [tg3]
  [<ffffffffa063f000>] ? 0xffffffffa063f000
  [<ffffffffa0644375>] tg3_poll_fw+0x85/0x150 [tg3]
  [<ffffffffa0649877>] tg3_chip_reset+0x357/0x8c0 [tg3]
  [<ffffffffa064ca8b>] tg3_halt+0x3b/0x190 [tg3]
  [<ffffffffa0657611>] tg3_stop+0x171/0x230 [tg3]
  ...
  [<ffffffffa064c550>] tg3_remove_one+0x90/0x140 [tg3]
  [<ffffffff813bee59>] pci_device_remove+0x39/0xc0
  [<ffffffff814a3201>] __device_release_driver+0xa1/0x160
  [<ffffffff814a32e3>] device_release_driver+0x23/0x30
  [<ffffffff813b794a>] pci_stop_bus_device+0x8a/0xa0
  [<ffffffff813b7ab6>] pci_stop_root_bus+0x36/0x60
  [<ffffffffa02c3f38>] hv_pci_remove+0x238/0x260 [pci_hyperv]

The problem seems to be that we report local resources release before
stopping the bus and removing devices from it and device drivers may try to
perform some operations with these resources on shutdown.  Move resources
release report after we do pci_stop_root_bus().

Signed-off-by: Vitaly Kuznetsov <vkuznets at redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
Acked-by: Jake Oshins <jakeo at microsoft.com>
---
 drivers/pci/host/pci-hyperv.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index f2559b6..c17e792 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -2268,11 +2268,6 @@ static int hv_pci_remove(struct hv_device *hdev)
 
 	hbus = hv_get_drvdata(hdev);
 
-	ret = hv_send_resources_released(hdev);
-	if (ret)
-		dev_err(&hdev->device,
-			"Couldn't send resources released packet(s)\n");
-
 	memset(&pkt.teardown_packet, 0, sizeof(pkt.teardown_packet));
 	init_completion(&comp_pkt.host_event);
 	pkt.teardown_packet.completion_func = hv_pci_generic_compl;
@@ -2295,6 +2290,11 @@ static int hv_pci_remove(struct hv_device *hdev)
 		pci_unlock_rescan_remove();
 	}
 
+	ret = hv_send_resources_released(hdev);
+	if (ret)
+		dev_err(&hdev->device,
+			"Couldn't send resources released packet(s)\n");
+
 	vmbus_close(hdev->channel);
 
 	/* Delete any children which might still exist. */
-- 
2.7.4