diff options
Diffstat (limited to 'drivers/hv/ring_buffer.c')
| -rw-r--r-- | drivers/hv/ring_buffer.c | 116 |
1 files changed, 101 insertions, 15 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 87799e81af97..1f450c39a9b0 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: @@ -73,8 +75,6 @@ static void hv_signal_on_write(u32 old_write, struct vmbus_channel *channel) */ if (old_write == READ_ONCE(rbi->ring_buffer->read_index)) vmbus_setevent(channel); - - return; } /* Get the next write location for the specified ring buffer. */ @@ -208,6 +208,7 @@ void hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info, ring_info->ring_buffer->interrupt_mask; } } +EXPORT_SYMBOL_GPL(hv_ringbuffer_get_debuginfo); /* Initialize the ring buffer. */ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, @@ -267,14 +268,13 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) int hv_ringbuffer_write(struct vmbus_channel *channel, const struct kvec *kv_list, u32 kv_count) { - int i = 0; + int i; u32 bytes_avail_towrite; - u32 totalbytes_towrite = 0; - + u32 totalbytes_towrite = sizeof(u64); u32 next_write_location; u32 old_write; - u64 prev_indices = 0; - unsigned long flags = 0; + u64 prev_indices; + unsigned long flags; struct hv_ring_buffer_info *outring_info = &channel->outbound; if (channel->rescind) @@ -283,8 +283,6 @@ int hv_ringbuffer_write(struct vmbus_channel *channel, for (i = 0; i < kv_count; i++) totalbytes_towrite += kv_list[i].iov_len; - totalbytes_towrite += sizeof(u64); - spin_lock_irqsave(&outring_info->ring_lock, flags); bytes_avail_towrite = hv_get_bytes_to_write(outring_info); @@ -336,23 +334,27 @@ 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) { u32 bytes_avail_toread; - u32 next_read_location = 0; + u32 next_read_location; u64 prev_indices = 0; struct vmpacket_descriptor desc; u32 offset; u32 packetlen; - int ret = 0; struct hv_ring_buffer_info *inring_info = &channel->inbound; if (buflen <= 0) return -EINVAL; - *buffer_actual_len = 0; *requestid = 0; @@ -363,10 +365,11 @@ int hv_ringbuffer_read(struct vmbus_channel *channel, * No error is set when there is even no header, drivers are * supposed to analyze buffer_actual_len. */ - return ret; + return 0; } - 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), @@ -408,5 +411,88 @@ int hv_ringbuffer_read(struct vmbus_channel *channel, hv_signal_on_read(channel); - return ret; + return 0; +} + +/* + * 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); |