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

[KY Srinivasan]

> -----Original Message-----
> From: Greg KH <gregkh at linuxfoundation.org>
> Sent: Tuesday, October 16, 2018 10:07 PM
> To: KY Srinivasan <kys at microsoft.com>
> Cc: linux-kernel at vger.kernel.org; devel at linuxdriverproject.org;
> olaf at aepfle.de; apw at canonical.com; jasowang at redhat.com; Stephen
> Hemminger <sthemmin at microsoft.com>; Michael Kelley (EOSG)
> <Michael.H.Kelley at microsoft.com>; vkuznets <vkuznets at redhat.com>;
> Haiyang Zhang <haiyangz at microsoft.com>; Stable at 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 at linuxonhyperv.com wrote:
> > From: Dexuan Cui <decui at 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 at microsoft.com>
> > Cc: K. Y. Srinivasan <kys at microsoft.com>
> > Cc: Haiyang Zhang <haiyangz at microsoft.com>
> > Cc: Stephen Hemminger <sthemmin at microsoft.com>
> > Cc: <Stable at vger.kernel.org>
> > Signed-off-by: K. Y. Srinivasan <kys at 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