Drivers: hv: Eliminate the channel spinlock in the callback path (d3ba720d) · Commits · 戴 / test

drivers/hv/channel.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -471,18 +471,26 @@ int vmbus_teardown_gpadl(struct vmbus_channel *channel, u32 gpadl_handle)
		}
		EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);

		static void reset_channel_cb(void *arg)
		{
		struct vmbus_channel *channel = arg;

		channel->onchannel_callback = NULL;
		}

		static void vmbus_close_internal(struct vmbus_channel *channel)
		{
		struct vmbus_channel_close_channel *msg;
		int ret;
		unsigned long flags;

		channel->state = CHANNEL_OPEN_STATE;
		channel->sc_creation_callback = NULL;
		/* Stop callback and cancel the timer asap */
		spin_lock_irqsave(&channel->inbound_lock, flags);
		channel->onchannel_callback = NULL;
		spin_unlock_irqrestore(&channel->inbound_lock, flags);
		if (channel->target_cpu != smp_processor_id())
		smp_call_function_single(channel->target_cpu, reset_channel_cb,
		channel, true);
		else
		reset_channel_cb(channel);

		/* Send a closing message */

+7 −4

Original line number	Diff line number	Diff line
		@@ -365,7 +365,7 @@ static u32 next_vp;
		* performance critical channels (IDE, SCSI and Network) will be uniformly
		* distributed across all available CPUs.
		*/
		static u32 get_vp_index(uuid_le *type_guid)
		static void init_vp_index(struct vmbus_channel channel, uuid_le type_guid)
		{
		u32 cur_cpu;
		int i;
		@@ -387,10 +387,13 @@ static u32 get_vp_index(uuid_le *type_guid)
		* Also if the channel is not a performance critical
		* channel, bind it to cpu 0.
		*/
		return 0;
		channel->target_cpu = 0;
		channel->target_vp = 0;
		return;
		}
		cur_cpu = (++next_vp % max_cpus);
		return hv_context.vp_index[cur_cpu];
		channel->target_cpu = cur_cpu;
		channel->target_vp = hv_context.vp_index[cur_cpu];
		}

		/*
		@@ -438,7 +441,7 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
		offer->connection_id;
		}

		newchannel->target_vp = get_vp_index(&offer->offer.if_type);
		init_vp_index(newchannel, &offer->offer.if_type);

		memcpy(&newchannel->offermsg, offer,
		sizeof(struct vmbus_channel_offer_channel));

+4 −7

Original line number	Diff line number	Diff line
		@@ -277,7 +277,6 @@ struct vmbus_channel *relid2channel(u32 relid)
		static void process_chn_event(u32 relid)
		{
		struct vmbus_channel *channel;
		unsigned long flags;
		void *arg;
		bool read_state;
		u32 bytes_to_read;
		@@ -296,13 +295,12 @@ static void process_chn_event(u32 relid)
		/*
		* A channel once created is persistent even when there
		* is no driver handling the device. An unloading driver
		* sets the onchannel_callback to NULL under the
		* protection of the channel inbound_lock. Thus, checking
		* and invoking the driver specific callback takes care of
		* orderly unloading of the driver.
		* sets the onchannel_callback to NULL on the same CPU
		* as where this interrupt is handled (in an interrupt context).
		* Thus, checking and invoking the driver specific callback takes
		* care of orderly unloading of the driver.
		*/

		spin_lock_irqsave(&channel->inbound_lock, flags);
		if (channel->onchannel_callback != NULL) {
		arg = channel->channel_callback_context;
		read_state = channel->batched_reading;
		@@ -327,7 +325,6 @@ static void process_chn_event(u32 relid)
		pr_err("no channel callback for relid - %u\n", relid);
		}

		spin_unlock_irqrestore(&channel->inbound_lock, flags);
		}

		/*

+2 −0

Original line number	Diff line number	Diff line
		@@ -696,6 +696,8 @@ struct vmbus_channel {
		* preserve the earlier behavior.
		*/
		u32 target_vp;
		/* The corresponding CPUID in the guest */
		u32 target_cpu;
		/*
		* Support for sub-channels. For high performance devices,
		* it will be useful to have multiple sub-channels to support