From: Dexuan Cui <de...@microsoft.com> Sent: Monday, August 19, 2019 6:52 PM
>
> Fake RESCIND_CHANNEL messages to clean up hv_sock channels by force for
> hibernation. There is no better method to clean up the channels since
> some of the channels may still be referenced by the userspace apps when
> hiberantin is triggered: in this case, the "rescind" fields of the
s/hiberantin/hibernation/
> channels are set, and the apps will thoroughly destroy the channels
> after hibernation.
>
> Signed-off-by: Dexuan Cui <de...@microsoft.com>
> ---
> drivers/hv/vmbus_drv.c | 55
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 55 insertions(+)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index ce9974b..2bea669 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -24,6 +24,7 @@
> #include <linux/sched/task_stack.h>
>
> #include <asm/mshyperv.h>
> +#include <linux/delay.h>
> #include <linux/notifier.h>
> #include <linux/ptrace.h>
> #include <linux/screen_info.h>
> @@ -1069,6 +1070,41 @@ void vmbus_on_msg_dpc(unsigned long data)
> vmbus_signal_eom(msg, message_type);
> }
>
> +/*
> + * Fake RESCIND_CHANNEL messages to clean up hv_sock channels by force for
> + * hibernation, because hv_sock connections can not persist across
> hibernation.
> + */
> +static void vmbus_force_channel_rescinded(struct vmbus_channel *channel)
> +{
> + struct onmessage_work_context *ctx;
> + struct vmbus_channel_rescind_offer *rescind;
> +
> + WARN_ON(!is_hvsock_channel(channel));
> +
> + /*
> + * sizeof(*ctx) is small and the allocation should really not fail,
> + * otherwise the state of the hv_sock connections ends up in limbo.
> + */
> + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL | __GFP_NOFAIL);
> +
> + /*
> + * So far, these are not really used by Linux. Just set them to the
> + * reasonable values conforming to the definitions of the fields.
> + */
> + ctx->msg.header.message_type = 1;
> + ctx->msg.header.payload_size = sizeof(*rescind);
> +
> + /* These values are actually used by Linux. */
> + rescind = (struct vmbus_channel_rescind_offer *)ctx->msg.u.payload;
> + rescind->header.msgtype = CHANNELMSG_RESCIND_CHANNELOFFER;
> + rescind->child_relid = channel->offermsg.child_relid;
> +
> + INIT_WORK(&ctx->work, vmbus_onmessage_work);
> +
> + queue_work_on(vmbus_connection.connect_cpu,
> + vmbus_connection.work_queue,
> + &ctx->work);
> +}
>
> /*
> * Direct callback for channels using other deferred processing
> @@ -2091,6 +2127,25 @@ static int vmbus_acpi_add(struct acpi_device *device)
>
> static int vmbus_bus_suspend(struct device *dev)
> {
> + struct vmbus_channel *channel;
> +
> + while (atomic_read(&vmbus_connection.offer_in_progress) != 0) {
> + /*
> + * We wait here until any channel offer is currently
> + * being processed.
> + */
The wording of the comment is a bit off. Maybe
/*
* We wait here until the completion of any channel
* offers that are currently in progress.
*/
> + msleep(1);
> + }
> +
> + mutex_lock(&vmbus_connection.channel_mutex);
> + list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
> + if (!is_hvsock_channel(channel))
> + continue;
> +
> + vmbus_force_channel_rescinded(channel);
> + }
> + mutex_unlock(&vmbus_connection.channel_mutex);
> +
> vmbus_initiate_unload(false);
>
> vmbus_connection.conn_state = DISCONNECTED;
> --
> 1.8.3.1
Modulo the nits:
Reviewed-by: Michael Kelley <mikel...@microsoft.com>
