linux-kernel - RE: [PATCH v3 12/12] Drivers: hv: vmbus: Resume after fixing up old primary channels

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Message-ID: <PU1P153MB0169999AD4830D9347C0990CBFBC0@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM>
Date:   Sat, 31 Aug 2019 05:08:21 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     Michael Kelley <mikelley@...rosoft.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>,
        "sashal@...nel.org" <sashal@...nel.org>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        KY Srinivasan <kys@...rosoft.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 12/12] Drivers: hv: vmbus: Resume after fixing up old
 primary channels

> From: Dexuan Cui
> Sent: Friday, August 30, 2019 9:37 PM
> > Is the intent to proceed and use the new offer?
> Yes, since this is not an error.
> 
> I'll add a comment before the "Mismatched offer from the host" for this.

Hi Michael, 
I'm going to make the below change in v4.

--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -956,7 +956,13 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
                        return;
                }

-               pr_debug("Mismatched offer from the host (relid=%d)\n",
+               /*
+                * This is not an error, since the host can also change the
+                * other field(s) of the offer, e.g. on WS RS5 (Build 17763),
+                * the offer->connection_id of the Mellanox VF vmbus device
+                * can change when the host reoffers the device upon resume.
+                */
+               pr_debug("vmbus offer changed: relid=%d\n",
                         offer->child_relid);

                print_hex_dump_debug("Old vmbus offer: ", DUMP_PREFIX_OFFSET,
@@ -965,6 +971,7 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
                print_hex_dump_debug("New vmbus offer: ", DUMP_PREFIX_OFFSET,
                                     16, 4, offer, offer_sz, false);

+               /* Fix up the old channel. */
                vmbus_setup_channel_state(oldchannel, offer);

                check_ready_for_resume_event();
Thanks,
-- Dexuan