[PATCH 5/7] Drivers: hv: vmbus: Ignore the offers when resuming from hibernation

Dexuan Cui
2019-07-09T05:29:41Z

When the VM resumes, the host re-sends the offers. We should not add the
offers to the global vmbus_connection.chn_list again.

Added some debug code, in case the host screws up the exact info related to
the offers.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
drivers/hv/channel_mgmt.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index addcef5..a9aeeab 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -854,12 +854,38 @@ void vmbus_initiate_unload(bool crash)
static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
{
struct vmbus_channel_offer_channel *offer;
- struct vmbus_channel *newchannel;
+ struct vmbus_channel *oldchannel, *newchannel;
+ size_t offer_sz;

offer = (struct vmbus_channel_offer_channel *)hdr;

trace_vmbus_onoffer(offer);

+ mutex_lock(&vmbus_connection.channel_mutex);
+ oldchannel = relid2channel(offer->child_relid);
+ mutex_unlock(&vmbus_connection.channel_mutex);
+
+ if (oldchannel != NULL) {
+ atomic_dec(&vmbus_connection.offer_in_progress);
+
+ /*
+ * We're resuming from hibernation: we expect the host to send
+ * exactly the same offers that we had before the hibernation.
+ */
+ offer_sz = sizeof(*offer);
+ if (memcmp(offer, &oldchannel->offermsg, offer_sz) == 0)
+ return;
+
+ pr_err("Mismatched offer from the host (relid=%d)!\n",
+ offer->child_relid);
+
+ print_hex_dump_debug("Old vmbus offer: ", DUMP_PREFIX_OFFSET, 4,
+ 4, &oldchannel->offermsg, offer_sz, false);
+ print_hex_dump_debug("New vmbus offer: ", DUMP_PREFIX_OFFSET, 4,
+ 4, offer, offer_sz, false);
+ return;
+ }
+
/* Allocate the channel object and save this offer. */
newchannel = alloc_channel();
if (!newchannel) {
--
1.8.3.1