hyperv/channel: Add debug sysctl nodes for channel indices

It would serve as a debug tool, if the shared buffer ring's indices
stopped updating.

Submitted by:	HongJiang Zhang <honzhan microsoft com>
Reviewed by:	sephe, Jun Su <junsu microsoft com>
Modified by:	sephe
MFC after:	1 week
Sponsored by:	Microsoft OSTC
Differential Revision:	https://reviews.freebsd.org/D5402

3 files changed, 116 insertions, 0 deletions

diff --git a/sys/dev/hyperv/vmbus/hv_channel.c b/sys/dev/hyperv/vmbus/hv_channel.c
index 9f97530..fa37bd5 100644
--- a/sys/dev/hyperv/vmbus/hv_channel.c
+++ b/sys/dev/hyperv/vmbus/hv_channel.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/mbuf.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
+#include <sys/sysctl.h>
 #include <machine/bus.h>
 #include <vm/vm.h>
 #include <vm/vm_param.h>
@@ -80,6 +81,68 @@ vmbus_channel_set_event(hv_vmbus_channel *channel)
 
 }
 
+static void
+hv_vmbus_channel_stat(hv_vmbus_channel* channel)
+{
+	device_t dev;
+	struct sysctl_oid *devch_sysctl;
+	struct sysctl_oid *devch_id_sysctl, *devch_sub_sysctl;
+	struct sysctl_oid *devch_id_in_sysctl, *devch_id_out_sysctl;
+	struct sysctl_ctx_list *ctx;
+	uint32_t ch_id;
+	uint16_t sub_ch_id;
+	char name[16];
+	
+	hv_vmbus_channel* primary_ch = channel->primary_channel;
+
+	if (primary_ch == NULL) {
+		dev = channel->device->device;
+		ch_id = channel->offer_msg.child_rel_id;
+	} else {
+		dev = primary_ch->device->device;
+		ch_id = primary_ch->offer_msg.child_rel_id;
+		sub_ch_id = channel->offer_msg.offer.sub_channel_index;
+	}
+	ctx = device_get_sysctl_ctx(dev);
+	/* This creates dev.DEVNAME.DEVUNIT.channel tree */
+	devch_sysctl = SYSCTL_ADD_NODE(ctx,
+		    SYSCTL_CHILDREN(device_get_sysctl_tree(dev)),
+		    OID_AUTO, "channel", CTLFLAG_RD, 0, "");
+	/* This creates dev.DEVNAME.DEVUNIT.channel.CHANID tree */
+	snprintf(name, sizeof(name), "%d", ch_id);
+	devch_id_sysctl = SYSCTL_ADD_NODE(ctx,
+	    	    SYSCTL_CHILDREN(devch_sysctl),
+	    	    OID_AUTO, name, CTLFLAG_RD, 0, "");
+
+	if (primary_ch != NULL) {
+		devch_sub_sysctl = SYSCTL_ADD_NODE(ctx,
+			SYSCTL_CHILDREN(devch_id_sysctl),
+			OID_AUTO, "sub", CTLFLAG_RD, 0, "");
+		snprintf(name, sizeof(name), "%d", sub_ch_id);
+		devch_id_sysctl = SYSCTL_ADD_NODE(ctx,
+			SYSCTL_CHILDREN(devch_sub_sysctl),
+			OID_AUTO, name, CTLFLAG_RD, 0, "");
+	}
+	
+	devch_id_in_sysctl = SYSCTL_ADD_NODE(ctx,
+                    SYSCTL_CHILDREN(devch_id_sysctl),
+                    OID_AUTO,
+		    "in",
+		    CTLFLAG_RD, 0, "");
+	devch_id_out_sysctl = SYSCTL_ADD_NODE(ctx,
+                    SYSCTL_CHILDREN(devch_id_sysctl),
+                    OID_AUTO,
+		    "out",
+		    CTLFLAG_RD, 0, "");
+	hv_ring_buffer_stat(ctx,
+		SYSCTL_CHILDREN(devch_id_in_sysctl),
+		&(channel->inbound),
+		"inbound ring buffer stats");
+	hv_ring_buffer_stat(ctx,
+		SYSCTL_CHILDREN(devch_id_out_sysctl),
+		&(channel->outbound),
+		"outbound ring buffer stats");
+}
 /**
  * @brief Open the specified channel
  */
@@ -143,6 +206,9 @@ hv_vmbus_channel_open(
 		in,
 		recv_ring_buffer_size);
 
+	/* setup statistic tracking for this channel */
+	hv_vmbus_channel_stat(new_channel);
+
 	/**
 	 * Establish the gpadl for the ring buffer
 	 */
diff --git a/sys/dev/hyperv/vmbus/hv_ring_buffer.c b/sys/dev/hyperv/vmbus/hv_ring_buffer.c
index 5e4f52a..765a693 100644
--- a/sys/dev/hyperv/vmbus/hv_ring_buffer.c
+++ b/sys/dev/hyperv/vmbus/hv_ring_buffer.c
@@ -30,6 +30,7 @@
 #include <sys/param.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
+#include <sys/sysctl.h>
 
 #include "hv_vmbus_priv.h"
 
@@ -37,6 +38,47 @@
 #define	HV_BYTES_AVAIL_TO_WRITE(r, w, z) ((w) >= (r))? \
 				((z) - ((w) - (r))):((r) - (w))
 
+static int
+hv_rbi_sysctl_stats(SYSCTL_HANDLER_ARGS)
+{
+	hv_vmbus_ring_buffer_info* rbi;
+	uint32_t read_index, write_index, interrupt_mask, sz;
+	uint32_t read_avail, write_avail;
+	char rbi_stats[256];
+
+	rbi = (hv_vmbus_ring_buffer_info*)arg1;
+	read_index = rbi->ring_buffer->read_index;
+	write_index = rbi->ring_buffer->write_index;
+	interrupt_mask = rbi->ring_buffer->interrupt_mask;
+	sz = rbi->ring_data_size;
+	write_avail = HV_BYTES_AVAIL_TO_WRITE(read_index,
+			write_index, sz);
+	read_avail = sz - write_avail;
+	snprintf(rbi_stats, sizeof(rbi_stats),
+		"r_idx:%d "
+		"w_idx:%d "
+		"int_mask:%d "
+		"r_avail:%d "
+		"w_avail:%d",
+		read_index, write_index, interrupt_mask,
+		read_avail, write_avail);
+
+	return (sysctl_handle_string(oidp, rbi_stats,
+			sizeof(rbi_stats), req));
+}
+
+void
+hv_ring_buffer_stat(
+	struct sysctl_ctx_list		*ctx,
+	struct sysctl_oid_list		*tree_node,
+	hv_vmbus_ring_buffer_info	*rbi,
+	const char			*desc)	
+{
+	SYSCTL_ADD_PROC(ctx, tree_node, OID_AUTO,
+	    "ring_buffer_stats",
+	    CTLTYPE_STRING|CTLFLAG_RD, rbi, 0,
+	    hv_rbi_sysctl_stats, "A", desc);
+}
 /**
  * @brief Get number of bytes available to read and to write to
  * for the specified ring buffer
diff --git a/sys/dev/hyperv/vmbus/hv_vmbus_priv.h b/sys/dev/hyperv/vmbus/hv_vmbus_priv.h
index 5f62072..62fa22a 100644
--- a/sys/dev/hyperv/vmbus/hv_vmbus_priv.h
+++ b/sys/dev/hyperv/vmbus/hv_vmbus_priv.h
@@ -639,6 +639,14 @@ extern hv_vmbus_channel_msg_table_entry	g_channel_message_table[];
 /*
  * Private, VM Bus functions
  */
+struct sysctl_ctx_list;
+struct sysctl_oid_list;
+
+void			hv_ring_buffer_stat(
+				struct sysctl_ctx_list		*ctx,
+				struct sysctl_oid_list		*tree_node,
+				hv_vmbus_ring_buffer_info	*rbi,
+				const char			*desc);
 
 int			hv_vmbus_ring_buffer_init(
 				hv_vmbus_ring_buffer_info	*ring_info,