Subject: Re: [PATCH V5 7/9] Drivers: hv: vmbus: add a mechanism to pass hvsock events to the hvsock driver

From: Vitaly Kuznetsov <[email-masked]>
Date: Tue, 05 Jan 2016 13:47:04 +0100

Dexuan Cui <[email-masked]> writes:

> For now only 1 event is defined: HVSOCK_RESCIND_CHANNEL.
> We'll have more events in the future.
>
> Signed-off-by: Dexuan Cui <[email-masked]>
> ---
>  drivers/hv/channel_mgmt.c | 18 ++++++++++++++++++
>  include/linux/hyperv.h    | 17 +++++++++++++++++
>  2 files changed, 35 insertions(+)
>
> diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
> index 4611b50..87fc7d2 100644
> --- a/drivers/hv/channel_mgmt.c
> +++ b/drivers/hv/channel_mgmt.c
> @@ -608,6 +608,16 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
>  	spin_unlock_irqrestore(&channel->lock, flags);
>
>  	if (channel->device_obj) {
> +		if (is_hvsock_channel(channel) &&
> +		    channel->hvsock_event_callback) {
> +			channel->hvsock_event_callback(channel,
> +						       HVSOCK_RESCIND_CHANNEL);
> +			/*
> +			 * We can't invoke vmbus_device_unregister()
> +			 * until the socket fd is closed.
> +			 */
> +			return;
> +		}
>  		/*
>  		 * We will have to unregister this device from the
>  		 * driver core.
> @@ -977,3 +987,11 @@ bool vmbus_are_subchannels_present(struct vmbus_channel *primary)
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(vmbus_are_subchannels_present);
> +
> +void vmbus_set_hvsock_event_callback(struct vmbus_channel *channel,
> +		void (*hvsock_event_callback)(struct vmbus_channel *,
> +					      enum hvsock_event))
> +{
> +	channel->hvsock_event_callback = hvsock_event_callback;
> +}
> +EXPORT_SYMBOL_GPL(vmbus_set_hvsock_event_callback);
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index b4cc44c..7e507bb 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -645,6 +645,12 @@ enum hv_signal_policy {
>  	HV_SIGNAL_POLICY_EXPLICIT,
>  };
>
> +/* hvsock related definitions */
> +enum hvsock_event {
> +	/* The host application is close()-ing the connection */
> +	HVSOCK_RESCIND_CHANNEL,
> +};
> +
>  struct vmbus_channel {
>  	/* Unique channel id */
>  	int id;
> @@ -740,6 +746,13 @@ struct vmbus_channel {
>  	void (*sc_creation_callback)(struct vmbus_channel *new_sc);
>
>  	/*
> +	 * hvsock event callback.
> +	 * For now only 1 event is defined: HVSOCK_RESCIND_CHANNEL.
> +	 */
> +	void (*hvsock_event_callback)(struct vmbus_channel *channel,
> +				      enum hvsock_event event);

Would it make sense to rename it to something more general,
e.g. sc_rescind_callback and call it for all drivers (even if we don't
need it now) intead of introducing enum hvsock_event? When new events
arrive we'll just add new callbacks (or, alternatively, we could unify
it to 'channel_event_callback' and merging with sc_creation_callback()
but I'd say it is uglier).

> +
> +	/*
>  	 * The spinlock to protect the structure. It is being used to protect
>  	 * test-and-set access to various attributes of the structure as well
>  	 * as all sc_list operations.
> @@ -825,6 +838,10 @@ int vmbus_request_offers(void);
>  void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
>  			void (*sc_cr_cb)(struct vmbus_channel *new_sc));
>
> +void vmbus_set_hvsock_event_callback(struct vmbus_channel *channel,
> +		void (*hvsock_event_callback)(struct vmbus_channel *,
> +					      enum hvsock_event));
> +
>  /*
>   * Retrieve the (sub) channel on which to send an outgoing request.
>   * When a primary channel has multiple sub-channels, we choose a

-- 
  Vitaly