[PATCH] vmbus: fix subchannel removal

Stephen Hemminger stephen at networkplumber.org
Fri Dec 7 18:58:47 UTC 2018

The changes to split ring allocation from open/close, broke
the cleanup of subchannels. This resulted in problems using
uio on network devices because the subchannel was left behind
when the network device was unbound.

The cause was in the disconnect logic which used list splice
to move the subchannel list into a local variable. This won't
work because the subchannel list is needed later during the
process of the rescind messages (relid2channel).

The fix is to just leave the subchannel list in place
which is what the original code did. The list is cleaned
up later when the host rescind is processed.

Fixes: ae6935ed7d42 ("vmbus: split ring buffer allocation from open")
Signed-off-by: Stephen Hemminger <sthemmin at microsoft.com>
 drivers/hv/channel.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index fe00b12e4417..bea4c9850247 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -701,20 +701,12 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
 int vmbus_disconnect_ring(struct vmbus_channel *channel)
 	struct vmbus_channel *cur_channel, *tmp;
-	unsigned long flags;
-	LIST_HEAD(list);
 	int ret;
 	if (channel->primary_channel != NULL)
 		return -EINVAL;
-	/* Snapshot the list of subchannels */
-	spin_lock_irqsave(&channel->lock, flags);
-	list_splice_init(&channel->sc_list, &list);
-	channel->num_sc = 0;
-	spin_unlock_irqrestore(&channel->lock, flags);
-	list_for_each_entry_safe(cur_channel, tmp, &list, sc_list) {
+	list_for_each_entry_safe(cur_channel, tmp, &channel->sc_list, sc_list) {
 		if (cur_channel->rescind)

More information about the devel mailing list