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

KY Srinivasan
2018-10-17T06:02:02Z

> -----Original Message-----
> From: Greg KH <gregkh@linuxfoundation.org>
> Sent: Tuesday, October 16, 2018 10:07 PM
> To: KY Srinivasan <kys@microsoft.com>
> Cc: linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> olaf@aepfle.de; apw@canonical.com; jasowang@redhat.com; Stephen
> Hemminger <sthemmin@microsoft.com>; Michael Kelley (EOSG)
> <Michael.H.Kelley@microsoft.com>; vkuznets <vkuznets@redhat.com>;
> Haiyang Zhang <haiyangz@microsoft.com>; Stable@vger.kernel.org
> Subject: Re: [PATCH 3/5] Drivers: hv: kvp: Fix the recent regression caused by
> incorrect clean-up
>
> 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?

Yes; a common should be sufficient.
>
>
> > +
> > + 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