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

Greg KH
2018-10-17T05:07:05Z

On Wed, Oct 17, 2018 at 03:14:04AM +0000, kys@linuxonhyperv.com wrote:
> 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..9fbb15c62c6c 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;
>
> + __attribute__ ((fallthrough));

The comment should be sufficient for this, right? I haven't seen many
uses of this attribute before, how common is it?

> +
> + 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;

Worst indentation ever :(

Yeah, I know it follows the others above it, but you should reconsider
it in the future...

thanks,

greg k-h