diff options
author | stephen hemminger <stephen@networkplumber.org> | 2017-02-27 10:26:48 -0800 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-03-06 17:13:13 -0800 |
commit | f3dd3f4797652c311df9c074436d420f1ad3566e (patch) | |
tree | 029e7602f0594a5b805828c33c40448cdb58623f /drivers/hv/ring_buffer.c | |
parent | 50698d80f8bb1db989b7b9fa433f588fade5e382 (diff) | |
download | linux-f3dd3f4797652c311df9c074436d420f1ad3566e.tar.bz2 |
vmbus: introduce in-place packet iterator
This is mostly just a refactoring of previous functions
(get_pkt_next_raw, put_pkt_raw and commit_rd_index) to make it easier
to use for other drivers and NAPI.
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/hv/ring_buffer.c')
-rw-r--r-- | drivers/hv/ring_buffer.c | 94 |
1 files changed, 93 insertions, 1 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 87799e81af97..c3f1a9e33cef 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -32,6 +32,8 @@ #include "hyperv_vmbus.h" +#define VMBUS_PKT_TRAILER 8 + /* * When we write to the ring buffer, check if the host needs to * be signaled. Here is the details of this protocol: @@ -336,6 +338,12 @@ int hv_ringbuffer_write(struct vmbus_channel *channel, return 0; } +static inline void +init_cached_read_index(struct hv_ring_buffer_info *rbi) +{ + rbi->cached_read_index = rbi->ring_buffer->read_index; +} + int hv_ringbuffer_read(struct vmbus_channel *channel, void *buffer, u32 buflen, u32 *buffer_actual_len, u64 *requestid, bool raw) @@ -366,7 +374,8 @@ int hv_ringbuffer_read(struct vmbus_channel *channel, return ret; } - init_cached_read_index(channel); + init_cached_read_index(inring_info); + next_read_location = hv_get_next_read_location(inring_info); next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc, sizeof(desc), @@ -410,3 +419,86 @@ int hv_ringbuffer_read(struct vmbus_channel *channel, return ret; } + +/* + * Determine number of bytes available in ring buffer after + * the current iterator (priv_read_index) location. + * + * This is similar to hv_get_bytes_to_read but with private + * read index instead. + */ +static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi) +{ + u32 priv_read_loc = rbi->priv_read_index; + u32 write_loc = READ_ONCE(rbi->ring_buffer->write_index); + + if (write_loc >= priv_read_loc) + return write_loc - priv_read_loc; + else + return (rbi->ring_datasize - priv_read_loc) + write_loc; +} + +/* + * Get first vmbus packet from ring buffer after read_index + * + * If ring buffer is empty, returns NULL and no other action needed. + */ +struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel) +{ + struct hv_ring_buffer_info *rbi = &channel->inbound; + + /* set state for later hv_signal_on_read() */ + init_cached_read_index(rbi); + + if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor)) + return NULL; + + return hv_get_ring_buffer(rbi) + rbi->priv_read_index; +} +EXPORT_SYMBOL_GPL(hv_pkt_iter_first); + +/* + * Get next vmbus packet from ring buffer. + * + * Advances the current location (priv_read_index) and checks for more + * data. If the end of the ring buffer is reached, then return NULL. + */ +struct vmpacket_descriptor * +__hv_pkt_iter_next(struct vmbus_channel *channel, + const struct vmpacket_descriptor *desc) +{ + struct hv_ring_buffer_info *rbi = &channel->inbound; + u32 packetlen = desc->len8 << 3; + u32 dsize = rbi->ring_datasize; + + /* bump offset to next potential packet */ + rbi->priv_read_index += packetlen + VMBUS_PKT_TRAILER; + if (rbi->priv_read_index >= dsize) + rbi->priv_read_index -= dsize; + + /* more data? */ + if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor)) + return NULL; + else + return hv_get_ring_buffer(rbi) + rbi->priv_read_index; +} +EXPORT_SYMBOL_GPL(__hv_pkt_iter_next); + +/* + * Update host ring buffer after iterating over packets. + */ +void hv_pkt_iter_close(struct vmbus_channel *channel) +{ + struct hv_ring_buffer_info *rbi = &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(); + rbi->ring_buffer->read_index = rbi->priv_read_index; + + hv_signal_on_read(channel); +} +EXPORT_SYMBOL_GPL(hv_pkt_iter_close); |