Commit 7769e18c authored by Andrea Parri (Microsoft)'s avatar Andrea Parri (Microsoft) Committed by Wei Liu
Browse files

scsi: storvsc: Re-init stor_chns when a channel interrupt is re-assigned 



For each storvsc_device, storvsc keeps track of the channel target CPUs
associated to the device (alloced_cpus) and it uses this information to
fill a "cache" (stor_chns) mapping CPU->channel according to a certain
heuristic.  Update the alloced_cpus mask and the stor_chns array when a
channel of the storvsc device is re-assigned to a different CPU.

Signed-off-by: default avatarAndrea Parri (Microsoft) <parri.andrea@gmail.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: <linux-scsi@vger.kernel.org>
Link: https://lore.kernel.org/r/20200406001514.19876-12-parri.andrea@gmail.com


Reviewed-by; Long Li <longli@microsoft.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
[ wei: fix a small issue reported by kbuild test robot <lkp@intel.com> ]
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent 75278105

drivers/hv/vmbus_drv.c

+4 −0
Original line number Diff line number Diff line
@@ -1777,6 +1777,10 @@ static ssize_t target_cpu_store(struct vmbus_channel *channel, 
	 * in on a CPU that is different from the channel target_cpu value.

	 */



	if (channel->change_target_cpu_callback)

		(*channel->change_target_cpu_callback)(channel,

				channel->target_cpu, target_cpu);



	channel->target_cpu = target_cpu;

	channel->target_vp = hv_cpu_number_to_vp_number(target_cpu);

	channel->numa_node = cpu_to_node(target_cpu);

drivers/scsi/storvsc_drv.c

+88 −8
Original line number Diff line number Diff line
@@ -621,6 +621,64 @@ get_in_err: 


}



static void storvsc_change_target_cpu(struct vmbus_channel *channel, u32 old,

				      u32 new)

{

	struct storvsc_device *stor_device;

	struct vmbus_channel *cur_chn;

	bool old_is_alloced = false;

	struct hv_device *device;

	unsigned long flags;

	int cpu;



	device = channel->primary_channel ?

			channel->primary_channel->device_obj

				: channel->device_obj;

	stor_device = get_out_stor_device(device);

	if (!stor_device)

		return;



	/* See storvsc_do_io() -> get_og_chn(). */

	spin_lock_irqsave(&device->channel->lock, flags);



	/*

	 * Determines if the storvsc device has other channels assigned to

	 * the "old" CPU to update the alloced_cpus mask and the stor_chns

	 * array.

	 */

	if (device->channel != channel && device->channel->target_cpu == old) {

		cur_chn = device->channel;

		old_is_alloced = true;

		goto old_is_alloced;

	}

	list_for_each_entry(cur_chn, &device->channel->sc_list, sc_list) {

		if (cur_chn == channel)

			continue;

		if (cur_chn->target_cpu == old) {

			old_is_alloced = true;

			goto old_is_alloced;

		}

	}



old_is_alloced:

	if (old_is_alloced)

		WRITE_ONCE(stor_device->stor_chns[old], cur_chn);

	else

		cpumask_clear_cpu(old, &stor_device->alloced_cpus);



	/* "Flush" the stor_chns array. */

	for_each_possible_cpu(cpu) {

		if (stor_device->stor_chns[cpu] && !cpumask_test_cpu(

					cpu, &stor_device->alloced_cpus))

			WRITE_ONCE(stor_device->stor_chns[cpu], NULL);

	}



	WRITE_ONCE(stor_device->stor_chns[new], channel);

	cpumask_set_cpu(new, &stor_device->alloced_cpus);



	spin_unlock_irqrestore(&device->channel->lock, flags);

}



static void handle_sc_creation(struct vmbus_channel *new_sc)

{

	struct hv_device *device = new_sc->primary_channel->device_obj;
@@ -648,6 +706,8 @@ static void handle_sc_creation(struct vmbus_channel *new_sc) 
		return;

	}



	new_sc->change_target_cpu_callback = storvsc_change_target_cpu;



	/* Add the sub-channel to the array of available channels. */

	stor_device->stor_chns[new_sc->target_cpu] = new_sc;

	cpumask_set_cpu(new_sc->target_cpu, &stor_device->alloced_cpus);
@@ -876,6 +936,8 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc) 
	if (stor_device->stor_chns == NULL)

		return -ENOMEM;



	device->channel->change_target_cpu_callback = storvsc_change_target_cpu;



	stor_device->stor_chns[device->channel->target_cpu] = device->channel;

	cpumask_set_cpu(device->channel->target_cpu,

			&stor_device->alloced_cpus);
@@ -1248,8 +1310,10 @@ static struct vmbus_channel *get_og_chn(struct storvsc_device *stor_device, 
	const struct cpumask *node_mask;

	int num_channels, tgt_cpu;



	if (stor_device->num_sc == 0)

	if (stor_device->num_sc == 0) {

		stor_device->stor_chns[q_num] = stor_device->device->channel;

		return stor_device->device->channel;

	}



	/*

	 * Our channel array is sparsley populated and we
@@ -1258,7 +1322,6 @@ static struct vmbus_channel *get_og_chn(struct storvsc_device *stor_device, 
	 * The strategy is simple:

	 * I. Ensure NUMA locality

	 * II. Distribute evenly (best effort)

	 * III. Mapping is persistent.

	 */



	node_mask = cpumask_of_node(cpu_to_node(q_num));
@@ -1268,8 +1331,10 @@ static struct vmbus_channel *get_og_chn(struct storvsc_device *stor_device, 
		if (cpumask_test_cpu(tgt_cpu, node_mask))

			num_channels++;

	}

	if (num_channels == 0)

	if (num_channels == 0) {

		stor_device->stor_chns[q_num] = stor_device->device->channel;

		return stor_device->device->channel;

	}



	hash_qnum = q_num;

	while (hash_qnum >= num_channels)
@@ -1295,6 +1360,7 @@ static int storvsc_do_io(struct hv_device *device, 
	struct storvsc_device *stor_device;

	struct vstor_packet *vstor_packet;

	struct vmbus_channel *outgoing_channel, *channel;

	unsigned long flags;

	int ret = 0;

	const struct cpumask *node_mask;

	int tgt_cpu;
@@ -1308,10 +1374,11 @@ static int storvsc_do_io(struct hv_device *device, 


	request->device  = device;

	/*

	 * Select an an appropriate channel to send the request out.

	 * Select an appropriate channel to send the request out.

	 */

	if (stor_device->stor_chns[q_num] != NULL) {

		outgoing_channel = stor_device->stor_chns[q_num];

	/* See storvsc_change_target_cpu(). */

	outgoing_channel = READ_ONCE(stor_device->stor_chns[q_num]);

	if (outgoing_channel != NULL) {

		if (outgoing_channel->target_cpu == q_num) {

			/*

			 * Ideally, we want to pick a different channel if
@@ -1324,7 +1391,10 @@ static int storvsc_do_io(struct hv_device *device, 
					continue;

				if (tgt_cpu == q_num)

					continue;

				channel = stor_device->stor_chns[tgt_cpu];

				channel = READ_ONCE(

					stor_device->stor_chns[tgt_cpu]);

				if (channel == NULL)

					continue;

				if (hv_get_avail_to_write_percent(

							&channel->outbound)

						> ring_avail_percent_lowater) {
@@ -1350,7 +1420,10 @@ static int storvsc_do_io(struct hv_device *device, 
			for_each_cpu(tgt_cpu, &stor_device->alloced_cpus) {

				if (cpumask_test_cpu(tgt_cpu, node_mask))

					continue;

				channel = stor_device->stor_chns[tgt_cpu];

				channel = READ_ONCE(

					stor_device->stor_chns[tgt_cpu]);

				if (channel == NULL)

					continue;

				if (hv_get_avail_to_write_percent(

							&channel->outbound)

						> ring_avail_percent_lowater) {
@@ -1360,7 +1433,14 @@ static int storvsc_do_io(struct hv_device *device, 
			}

		}

	} else {

		spin_lock_irqsave(&device->channel->lock, flags);

		outgoing_channel = stor_device->stor_chns[q_num];

		if (outgoing_channel != NULL) {

			spin_unlock_irqrestore(&device->channel->lock, flags);

			goto found_channel;

		}

		outgoing_channel = get_og_chn(stor_device, q_num);

		spin_unlock_irqrestore(&device->channel->lock, flags);

	}



found_channel:

include/linux/hyperv.h

+3 −0
Original line number Diff line number Diff line
@@ -773,6 +773,9 @@ struct vmbus_channel { 
	void (*onchannel_callback)(void *context);

	void *channel_callback_context;



	void (*change_target_cpu_callback)(struct vmbus_channel *channel,

			u32 old, u32 new);



	/*

	 * Synchronize channel scheduling and channel removal; see the inline

	 * comments in vmbus_chan_sched() and vmbus_reset_channel_cb().

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