diff options
| -rw-r--r-- | drivers/hv/ring_buffer.c | 1 | ||||
| -rw-r--r-- | include/linux/hyperv.h | 86 |
2 files changed, 87 insertions, 0 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index dd255c9b9420..fe586bf74e17 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -132,6 +132,7 @@ hv_set_next_read_location(struct hv_ring_buffer_info *ring_info, u32 next_read_location) { ring_info->ring_buffer->read_index = next_read_location; + ring_info->priv_read_index = next_read_location; } /* Get the size of the ring buffer. */ diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index eb7c0b215ba4..590fee6a2e6f 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -126,6 +126,8 @@ struct hv_ring_buffer_info { u32 ring_datasize; /* < ring_size */ u32 ring_data_startoffset; + u32 priv_write_index; + u32 priv_read_index; }; /* @@ -1420,4 +1422,88 @@ static inline bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi) return false; } +/* + * An API to support in-place processing of incoming VMBUS packets. + */ +#define VMBUS_PKT_TRAILER 8 + +static inline struct vmpacket_descriptor * +get_next_pkt_raw(struct vmbus_channel *channel) +{ + struct hv_ring_buffer_info *ring_info = &channel->inbound; + u32 read_loc = ring_info->priv_read_index; + void *ring_buffer = hv_get_ring_buffer(ring_info); + struct vmpacket_descriptor *cur_desc; + u32 packetlen; + u32 dsize = ring_info->ring_datasize; + u32 delta = read_loc - ring_info->ring_buffer->read_index; + u32 bytes_avail_toread = (hv_get_bytes_to_read(ring_info) - delta); + + if (bytes_avail_toread < sizeof(struct vmpacket_descriptor)) + return NULL; + + if ((read_loc + sizeof(*cur_desc)) > dsize) + return NULL; + + cur_desc = ring_buffer + read_loc; + packetlen = cur_desc->len8 << 3; + + /* + * If the packet under consideration is wrapping around, + * return failure. + */ + if ((read_loc + packetlen + VMBUS_PKT_TRAILER) > (dsize - 1)) + return NULL; + + return cur_desc; +} + +/* + * A helper function to step through packets "in-place" + * This API is to be called after each successful call + * get_next_pkt_raw(). + */ +static inline void put_pkt_raw(struct vmbus_channel *channel, + struct vmpacket_descriptor *desc) +{ + struct hv_ring_buffer_info *ring_info = &channel->inbound; + u32 read_loc = ring_info->priv_read_index; + u32 packetlen = desc->len8 << 3; + u32 dsize = ring_info->ring_datasize; + + if ((read_loc + packetlen + VMBUS_PKT_TRAILER) > dsize) + BUG(); + /* + * Include the packet trailer. + */ + ring_info->priv_read_index += packetlen + VMBUS_PKT_TRAILER; +} + +/* + * This call commits the read index and potentially signals the host. + * Here is the pattern for using the "in-place" consumption APIs: + * + * while (get_next_pkt_raw() { + * process the packet "in-place"; + * put_pkt_raw(); + * } + * if (packets processed in place) + * commit_rd_index(); + */ +static inline void commit_rd_index(struct vmbus_channel *channel) +{ + struct hv_ring_buffer_info *ring_info = &channel->inbound; + /* + * Make sure all reads are done before we update the read index since + * the writer may start writing to the read area once the read index + * is updated. + */ + virt_rmb(); + ring_info->ring_buffer->read_index = ring_info->priv_read_index; + + if (hv_need_to_signal_on_read(ring_info)) + vmbus_set_event(channel); +} + + #endif /* _HYPERV_H */ |