[PATCH] PCI: hv: report resources release after stopping the bus

[PATCH] PCI: hv: report resources release after stopping the bus

[Vitaly Kuznetsov]

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@redhat.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. */
-- 
2.5.5

RE: [PATCH] PCI: hv: report resources release after stopping the bus

[Jake Oshins]

> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> Sent: Friday, April 29, 2016 2:39 AM
> To: linux-pci@vger.kernel.org
> Cc: devel@linuxdriverproject.org; linux-kernel@vger.kernel.org; KY
> Srinivasan <kys@microsoft.com>; Haiyang Zhang
> <haiyangz@microsoft.com>; Bjorn Helgaas <bhelgaas@google.com>; Jake
> Oshins <jakeo@microsoft.com>
> Subject: [PATCH] PCI: hv: report resources release after stopping the bus
> 
> 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@redhat.com>
Acked-by: Jake Oshins <jakeo@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. */
> --
> 2.5.5

This looks like the right fix to me.  Thanks.

-- Jake Oshins

Re: [PATCH] PCI: hv: report resources release after stopping the bus

[Bjorn Helgaas]

On Fri, Apr 29, 2016 at 11:39:10AM +0200, Vitaly Kuznetsov wrote:
> 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@redhat.com>

Applied with Jake's ack to pci/host-hv for v4.7, thanks, Vitaly!

> ---
>  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. */
> -- 
> 2.5.5
> 
> --
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