linux-kernel - [PATCH 3/4] Drivers: hv: kvp: Fix two "this statement may fall through" warnings

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Message-Id: <20180923211044.27922-3-kys@linuxonhyperv.com>
Date:   Sun, 23 Sep 2018 21:10:43 +0000
From:   kys@...uxonhyperv.com
To:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
        jasowang@...hat.com, sthemmin@...rosoft.com,
        Michael.H.Kelley@...rosoft.com, vkuznets@...hat.com
Cc:     Dexuan Cui <decui@...rosoft.com>,
        "K . Y . Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>, Stable@...r.kernel.org
Subject: [PATCH 3/4] Drivers: hv: kvp: Fix two "this statement may fall through" warnings

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

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>
Cc: <Stable@...r.kernel.org>
Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
---
 drivers/hv/hv_kvp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index 023bd185d21a..a7513a8a8e37 100644
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -353,7 +353,6 @@ 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;
 
-	default:
 		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
 				MAX_ADAPTER_ID_SIZE,
 				UTF16_LITTLE_ENDIAN,
@@ -406,7 +405,7 @@ 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) {
@@ -446,6 +445,9 @@ kvp_send_key(struct work_struct *dummy)
 			break;
 
 		}
+
+		break;
+
 	case KVP_OP_GET:
 		message->body.kvp_set.data.key_size =
 			utf16s_to_utf8s(
-- 
2.18.0