svn commit: r304790 - in head/sys/dev/hyperv: include vmbus

[Sepherosa Ziehau]

Author: sephe
Date: Thu Aug 25 05:35:51 2016
New Revision: 304790
URL: https://svnweb.freebsd.org/changeset/base/304790

Log:
  hyperv/vmbus: Add function to calculate max # of elements in a bufring.
  
  MFC after:	1 week
  Sponsored by:	Microsoft

Modified:
  head/sys/dev/hyperv/include/vmbus.h
  head/sys/dev/hyperv/vmbus/vmbus_brvar.h
  head/sys/dev/hyperv/vmbus/vmbus_chan.c

Modified: head/sys/dev/hyperv/include/vmbus.h
==============================================================================
--- head/sys/dev/hyperv/include/vmbus.h	Thu Aug 25 05:28:02 2016	(r304789)
+++ head/sys/dev/hyperv/include/vmbus.h	Thu Aug 25 05:35:51 2016	(r304790)
@@ -161,5 +161,7 @@ uint32_t	vmbus_chan_subidx(const struct 
 bool		vmbus_chan_is_primary(const struct vmbus_channel *chan);
 const struct hyperv_guid *
 		vmbus_chan_guid_inst(const struct vmbus_channel *chan);
+int		vmbus_chan_prplist_nelem(int br_size, int prpcnt_max,
+		    int dlen_max);
 
 #endif	/* !_VMBUS_H_ */

Modified: head/sys/dev/hyperv/vmbus/vmbus_brvar.h
==============================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_brvar.h	Thu Aug 25 05:28:02 2016	(r304789)
+++ head/sys/dev/hyperv/vmbus/vmbus_brvar.h	Thu Aug 25 05:35:51 2016	(r304790)
@@ -74,6 +74,7 @@ struct sysctl_oid;
 static __inline int
 vmbus_txbr_maxpktsz(const struct vmbus_txbr *tbr)
 {
+
 	/*
 	 * - 64 bits for the trailing start index (- sizeof(uint64_t)).
 	 * - The rindex and windex can't be same (- 1).  See
@@ -82,6 +83,17 @@ vmbus_txbr_maxpktsz(const struct vmbus_t
 	return (tbr->txbr_dsize - sizeof(uint64_t) - 1);
 }
 
+static __inline int
+vmbus_br_nelem(int br_size, int elem_size)
+{
+
+	/* Strip bufring header */
+	br_size -= sizeof(struct vmbus_bufring);
+	/* Add per-element trailing index */
+	elem_size += sizeof(uint64_t);
+	return (br_size / elem_size);
+}
+
 void		vmbus_br_sysctl_create(struct sysctl_ctx_list *ctx,
 		    struct sysctl_oid *br_tree, struct vmbus_br *br,
 		    const char *name);

Modified: head/sys/dev/hyperv/vmbus/vmbus_chan.c
==============================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_chan.c	Thu Aug 25 05:28:02 2016	(r304789)
+++ head/sys/dev/hyperv/vmbus/vmbus_chan.c	Thu Aug 25 05:35:51 2016	(r304790)
@@ -1411,3 +1411,16 @@ vmbus_chan_guid_inst(const struct vmbus_
 {
 	return &chan->ch_guid_inst;
 }
+
+int
+vmbus_chan_prplist_nelem(int br_size, int prpcnt_max, int dlen_max)
+{
+	int elem_size;
+
+	elem_size = __offsetof(struct vmbus_chanpkt_prplist,
+	    cp_range[0].gpa_page[prpcnt_max]);
+	elem_size += dlen_max;
+	elem_size = VMBUS_CHANPKT_TOTLEN(elem_size);
+
+	return (vmbus_br_nelem(br_size, elem_size));
+}