> From: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
> Sent: Friday, December 7, 2018 10:59 AM
> To: KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang
> <haiyangz@xxxxxxxxxxxxx>; Dexuan Cui <decui@xxxxxxxxxxxxx>;
> mgamal@xxxxxxxxxx
> Cc: devel@xxxxxxxxxxxxxxxxxxxxxx; Stephen Hemminger
> <sthemmin@xxxxxxxxxxxxx>
> 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.
>
> Fixes: ae6935ed7d42 ("vmbus: split ring buffer allocation from open")
> Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
> ---
> 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)
> wait_for_completion(&cur_channel->rescind_event);
>
Reviewed-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
4.20-rc6 is out now. I hope this fix still has a chance to go in v4.20-final.
Thanks,
-- Dexuan
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