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hyperv/vmbus: Add function to calculate max # of elements in a bufring.

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MFC after:	1 week
Sponsored by:	Microsoft
This commit is contained in:
Sepherosa Ziehau 2016-08-25 05:35:51 +00:00
parent 1c828193df
commit dd9af4103b
3 changed files with 27 additions and 0 deletions
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2
sys/dev/hyperv/include/vmbus.h
View File

@ -161,5 +161,7 @@ uint32_t vmbus_chan_subidx(const struct vmbus_channel *chan);
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_ */

12
sys/dev/hyperv/vmbus/vmbus_brvar.h
View File

@ -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_txbr *tbr)
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);

13
sys/dev/hyperv/vmbus/vmbus_chan.c
View File

@ -1411,3 +1411,16 @@ vmbus_chan_guid_inst(const struct vmbus_channel *chan)
{
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));
}