linux-kernel - [PATCH 3.16 057/305] Drivers: hv: kvp: Fix two "this statement may fall through" warnings

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Date:   Sun, 03 Feb 2019 14:45:08 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        "Stephen Hemminger" <sthemmin@...rosoft.com>,
        "Dexuan Cui" <decui@...rosoft.com>,
        "Haiyang Zhang" <haiyangz@...rosoft.com>
Subject: [PATCH 3.16 057/305] Drivers: hv: kvp: Fix two "this statement
 may fall through" warnings

3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dexuan Cui <decui@...rosoft.com>

commit fc62c3b1977d62e6374fd6e28d371bb42dfa5c9d upstream.

We don't need to call process_ib_ipinfo() if message->kvp_hdr.operation is
KVP_OP_GET_IP_INFO in kvp_send_key(), because here we just need to pass on
the op code from the host to the userspace; when the userspace returns
the info requested by the host, we pass the info on to the host in
kvp_respond_to_host() -> process_ob_ipinfo(). BTW, the current buggy code
actually doesn't cause any harm, because only message->kvp_hdr.operation
is used by the userspace, in the case of KVP_OP_GET_IP_INFO.

The patch also adds a missing "break;" in kvp_send_key(). BTW, the current
buggy code actually doesn't cause any harm, because in the case of
KVP_OP_SET, the unexpected fall-through corrupts
message->body.kvp_set.data.key_size, but that is not really used: see
the definition of struct hv_kvp_exchg_msg_value.

Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Cc: K. Y. Srinivasan <kys@...rosoft.com>
Cc: Haiyang Zhang <haiyangz@...rosoft.com>
Cc: Stephen Hemminger <sthemmin@...rosoft.com>
Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/hv/hv_kvp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -326,7 +326,6 @@ static void process_ib_ipinfo(void *in_m

 		out->body.kvp_ip_val.dhcp_enabled = in->kvp_ip_val.dhcp_enabled;

-	default:
 		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
 				MAX_ADAPTER_ID_SIZE,
 				UTF16_LITTLE_ENDIAN,
@@ -379,7 +378,7 @@ 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:
-		process_ib_ipinfo(in_msg, message, KVP_OP_GET_IP_INFO);
+		/* We only need to pass on message->kvp_hdr.operation.  */
 		break;
 	case KVP_OP_SET:
 		switch (in_msg->body.kvp_set.data.value_type) {
@@ -419,6 +418,9 @@ kvp_send_key(struct work_struct *dummy)
 			break;

 		}
+
+		break;
+
 	case KVP_OP_GET:
 		message->body.kvp_set.data.key_size =
 			utf16s_to_utf8s(