linux-kernel - [PATCH v2 2/2] Drivers: hv: vmbus: Log on missing offers

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Message-Id: <20241029080147.52749-3-namjain@linux.microsoft.com>
Date: Tue, 29 Oct 2024 01:01:47 -0700
From: Naman Jain <namjain@...ux.microsoft.com>
To: "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-kernel@...r.kernel.org,
	Naman Jain <namjain@...ux.microsoft.com>,
	John Starks <jostarks@...rosoft.com>,
	jacob.pan@...ux.microsoft.com,
	Easwar Hariharan <eahariha@...ux.microsoft.com>,
	Michael Kelley <mhklinux@...look.com>,
	Saurabh Singh Sengar <ssengar@...ux.microsoft.com>
Subject: [PATCH v2 2/2] Drivers: hv: vmbus: Log on missing offers

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 essential virtual devices configured for a VM, remain
same, before and after the hibernation and its not very common that
some offers are missing. 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 as
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 v1:
https://lore.kernel.org/all/20241018115811.5530-1-namjain@linux.microsoft.com
* 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