On Mon, Jan 28, 2019 at 06:43:16PM +0000, Dexuan Cui wrote:
From: gregkh@xxxxxxxxxxxxxxxxxxx <gregkh@xxxxxxxxxxxxxxxxxxx> Sent: Monday, January 28, 2019 4:35 AM To: Dexuan Cui <decui@xxxxxxxxxxxxx>; sashal@xxxxxxxxxx; Stephen Hemminger <sthemmin@xxxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Subject: FAILED: patch "[PATCH] vmbus: fix subchannel removal" failed to apply to 4.20-stable tree The patch below does not apply to the 4.20-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From b5679cebf780c6f1c2451a73bf1842a4409840e7 Mon Sep 17 00:00:00 2001 From: Dexuan Cui <decui@xxxxxxxxxxxxx> Date: Wed, 9 Jan 2019 20:56:06 +0000 Subject: [PATCH] vmbus: fix subchannel removal 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@xxxxxxxxxxxxxxx Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> 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);Hi Sasha, Greg, We need to backport this patch to linux-4.20.y. To cleanly cherry-pick this patch (i.e. b5679cebf780 ("vmbus: fix subchannel removal")), we need to backport another patch first: 4d3c5c69191f ("Drivers: hv: vmbus: Remove the useless API vmbus_get_outgoing_channel()") Unluckily we can't cleanly git-cherry-pick 4d3c5c69191f, as a trivial rebase is required. I attached the rebased version, and let me also paste the patch below for your convenience.
I've queued your backport of 4d3c5c69191f and b5679cebf780 on top of it for 4.20, thank you. -- Thanks, Sasha
