linux-kernel - RE: [PATCH v3 2/2] Drivers: hv: vmbus: Log on missing offers if any

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Message-ID:
 <SN6PR02MB41579D449B5AEBD4E29F86ACD4302@SN6PR02MB4157.namprd02.prod.outlook.com>
Date: Thu, 5 Dec 2024 16:31:32 +0000
From: Michael Kelley <mhklinux@...look.com>
To: Naman Jain <namjain@...ux.microsoft.com>, "K . Y . Srinivasan"
	<kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu
	<wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>
CC: "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, John Starks
	<jostarks@...rosoft.com>, "jacob.pan@...ux.microsoft.com"
	<jacob.pan@...ux.microsoft.com>, Easwar Hariharan
	<eahariha@...ux.microsoft.com>, Saurabh Singh Sengar
	<ssengar@...ux.microsoft.com>
Subject: RE: [PATCH v3 2/2] Drivers: hv: vmbus: Log on missing offers if any

From: Naman Jain <namjain@...ux.microsoft.com> Sent: Wednesday, November 13, 2024 12:47 AM
> 
> From: John Starks <jostarks@...rosoft.com>
> 
> When resuming from hibernation, log any channels that were present
> before hibernation but now are gone.
> In general, the boot-time devices configured for a resuming VM should be
> the same as the devices in the VM at the time of hibernation. It's
> uncommon for the configuration to have been changed such that offers
> are missing. Changing the configuration violates the rules for
> hibernation anyway.
> The cleanup of missing channels is not straight-forward and dependent
> on individual device driver functionality and implementation,
> so it can be added in future with separate changes.
> 
> Signed-off-by: John Starks <jostarks@...rosoft.com>
> Co-developed-by: Naman Jain <namjain@...ux.microsoft.com>
> Signed-off-by: Naman Jain <namjain@...ux.microsoft.com>
> Reviewed-by: Easwar Hariharan <eahariha@...ux.microsoft.com>
> ---
> Changes since v2:
> * Addressed Michael's comments:
>   * Changed commit msg as per suggestions
> * Addressed Dexuan's comments, which came up in offline discussion:
>   * Minor additions in commit subject.
> 
> Changes since v1:
> * Added Easwar's Reviewed-By tag
> * Addressed Saurabh's comments:
>   * Added a note for missing channel cleanup in comments and commit msg
> ---
>  drivers/hv/vmbus_drv.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index bd3fc41dc06b..08214f28694a 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -2462,6 +2462,7 @@ static int vmbus_bus_suspend(struct device *dev)
> 
>  static int vmbus_bus_resume(struct device *dev)
>  {
> +	struct vmbus_channel *channel;
>  	struct vmbus_channel_msginfo *msginfo;
>  	size_t msgsize;
>  	int ret;
> @@ -2494,6 +2495,22 @@ static int vmbus_bus_resume(struct device *dev)
> 
>  	vmbus_request_offers();
> 
> +	mutex_lock(&vmbus_connection.channel_mutex);
> +	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
> +		if (channel->offermsg.child_relid != INVALID_RELID)
> +			continue;
> +
> +		/* hvsock channels are not expected to be present. */
> +		if (is_hvsock_channel(channel))
> +			continue;
> +
> +		pr_err("channel %pUl/%pUl not present after resume.\n",
> +			&channel->offermsg.offer.if_type,
> +			&channel->offermsg.offer.if_instance);
> +		/* ToDo: Cleanup these channels here */
> +	}
> +	mutex_unlock(&vmbus_connection.channel_mutex);
> +
>  	/* Reset the event for the next suspend. */
>  	reinit_completion(&vmbus_connection.ready_for_suspend_event);
> 
> --
> 2.34.1

Reviewed-by: Michael Kelley <mhklinux@...look.com>