[PATCH V2 3/5] Drivers: hv: kvp: Fix the recent regression caused by incorrect clean-up

[kys@linuxonhyperv.com]

From: Dexuan Cui <decui@microsoft.com>

In kvp_send_key(), we do need call process_ib_ipinfo() if
message->kvp_hdr.operation is KVP_OP_GET_IP_INFO, because it turns out
the userland hv_kvp_daemon needs the info of operation, adapter_id and
addr_family. With the incorrect fc62c3b1977d, the host can't get the
VM's IP via KVP.

And, fc62c3b1977d added a "break;", but actually forgot to initialize
the key_size/value in the case of KVP_OP_SET, so the default key_size of
0 is passed to the kvp daemon, and the pool files
/var/lib/hyperv/.kvp_pool_* can't be updated.

This patch effectively rolls back the previous fc62c3b1977d, and
correctly fixes the "this statement may fall through" warnings.

This patch is tested on WS 2012 R2 and 2016.

Fixes: fc62c3b1977d ("Drivers: hv: kvp: Fix two "this statement may fall through" warnings")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv_kvp.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index a7513a8a8e37..d6106e1a0d4a 100644
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -353,6 +353,9 @@ static void process_ib_ipinfo(void *in_msg, void *out_msg, int op)
 
 		out->body.kvp_ip_val.dhcp_enabled = in->kvp_ip_val.dhcp_enabled;
 
+		/* fallthrough */
+
+	case KVP_OP_GET_IP_INFO:
 		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
 				MAX_ADAPTER_ID_SIZE,
 				UTF16_LITTLE_ENDIAN,
@@ -405,7 +408,11 @@ kvp_send_key(struct work_struct *dummy)
 		process_ib_ipinfo(in_msg, message, KVP_OP_SET_IP_INFO);
 		break;
 	case KVP_OP_GET_IP_INFO:
-		/* We only need to pass on message->kvp_hdr.operation.  */
+		/*
+		 * We only need to pass on the info of operation, adapter_id
+		 * and addr_family to the userland kvp daemon.
+		 */
+		process_ib_ipinfo(in_msg, message, KVP_OP_GET_IP_INFO);
 		break;
 	case KVP_OP_SET:
 		switch (in_msg->body.kvp_set.data.value_type) {
@@ -446,9 +453,9 @@ kvp_send_key(struct work_struct *dummy)
 
 		}
 
-		break;
-
-	case KVP_OP_GET:
+		/*
+		 * The key is always a string - utf16 encoding.
+		 */
 		message->body.kvp_set.data.key_size =
 			utf16s_to_utf8s(
 			(wchar_t *)in_msg->body.kvp_set.data.key,
@@ -456,6 +463,17 @@ kvp_send_key(struct work_struct *dummy)
 			UTF16_LITTLE_ENDIAN,
 			message->body.kvp_set.data.key,
 			HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
+
+		break;
+
+	case KVP_OP_GET:
+		message->body.kvp_get.data.key_size =
+			utf16s_to_utf8s(
+			(wchar_t *)in_msg->body.kvp_get.data.key,
+			in_msg->body.kvp_get.data.key_size,
+			UTF16_LITTLE_ENDIAN,
+			message->body.kvp_get.data.key,
+			HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
 		break;
 
 	case KVP_OP_DELETE:
-- 
2.18.0