4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit b5679cebf780c6f1c2451a73bf1842a4409840e7 ]
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.
Without the fix, we have a lot of "hang" issues in netvsc when we try to change the NIC's MTU, set the number of channels, etc.
Fixes: ae6935ed7d42 ("vmbus: split ring buffer allocation from open") Cc: stable@vger.kernel.org Signed-off-by: Stephen Hemminger sthemmin@microsoft.com Signed-off-by: Dexuan Cui decui@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hv/channel.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c index ce0ba2062723..bea4c9850247 100644 --- a/drivers/hv/channel.c +++ b/drivers/hv/channel.c @@ -701,19 +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); - 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) wait_for_completion(&cur_channel->rescind_event);