/*
*
* hv_ringbuffer_read()
*
* Read and advance the read index
*
*/
int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
u32 buflen, u32 offset, bool *signal)
{
u32 bytes_avail_towrite;
u32 bytes_avail_toread;
u32 next_read_location = 0;
u64 prev_indices = 0;
unsigned long flags;
u32 old_read;
if (buflen <= 0)
return -EINVAL;
spin_lock_irqsave(&inring_info->ring_lock, flags);
hv_get_ringbuffer_availbytes(inring_info,
&bytes_avail_toread,
&bytes_avail_towrite);
old_read = bytes_avail_toread;
/* Make sure there is something to read */
if (bytes_avail_toread < buflen) {
spin_unlock_irqrestore(&inring_info->ring_lock, flags);
return -EAGAIN;
}
next_read_location =
hv_get_next_readlocation_withoffset(inring_info, offset);
next_read_location = hv_copyfrom_ringbuffer(inring_info,
buffer,
buflen,
next_read_location);
next_read_location = hv_copyfrom_ringbuffer(inring_info,
&prev_indices,
sizeof(u64),
next_read_location);
/* 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 */
mb();
/* Update the read index */
hv_set_next_read_location(inring_info, next_read_location);
spin_unlock_irqrestore(&inring_info->ring_lock, flags);
*signal = hv_need_to_signal_on_read(old_read, inring_info);
return 0;
}
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;
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;
bytes_avail_toread = hv_get_bytes_to_read(inring_info);
/* Make sure there is something to read */
if (bytes_avail_toread < sizeof(desc)) {
/*
* No error is set when there is even no header, drivers are
* supposed to analyze buffer_actual_len.
*/
return ret;
}
next_read_location = hv_get_next_read_location(inring_info);
next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc,
sizeof(desc),
next_read_location);
offset = raw ? 0 : (desc.offset8 << 3);
packetlen = (desc.len8 << 3) - offset;
*buffer_actual_len = packetlen;
*requestid = desc.trans_id;
if (bytes_avail_toread < packetlen + offset)
return -EAGAIN;
if (packetlen > buflen)
return -ENOBUFS;
next_read_location =
hv_get_next_readlocation_withoffset(inring_info, offset);
next_read_location = hv_copyfrom_ringbuffer(inring_info,
buffer,
packetlen,
next_read_location);
next_read_location = hv_copyfrom_ringbuffer(inring_info,
&prev_indices,
sizeof(u64),
next_read_location);
/*
* 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_mb();
/* Update the read index */
hv_set_next_read_location(inring_info, next_read_location);
hv_signal_on_read(channel);
return ret;
}
int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
void *buffer, u32 buflen, u32 *buffer_actual_len,
u64 *requestid, bool *signal, bool raw)
{
u32 bytes_avail_toread;
u32 next_read_location = 0;
u64 prev_indices = 0;
unsigned long flags;
struct vmpacket_descriptor desc;
u32 offset;
u32 packetlen;
int ret = 0;
if (buflen <= 0)
return -EINVAL;
spin_lock_irqsave(&inring_info->ring_lock, flags);
*buffer_actual_len = 0;
*requestid = 0;
bytes_avail_toread = hv_get_bytes_to_read(inring_info);
/* Make sure there is something to read */
if (bytes_avail_toread < sizeof(desc)) {
/*
* No error is set when there is even no header, drivers are
* supposed to analyze buffer_actual_len.
*/
goto out_unlock;
}
next_read_location = hv_get_next_read_location(inring_info);
next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc,
sizeof(desc),
next_read_location);
offset = raw ? 0 : (desc.offset8 << 3);
packetlen = (desc.len8 << 3) - offset;
*buffer_actual_len = packetlen;
*requestid = desc.trans_id;
if (bytes_avail_toread < packetlen + offset) {
ret = -EAGAIN;
goto out_unlock;
}
if (packetlen > buflen) {
ret = -ENOBUFS;
goto out_unlock;
}
next_read_location =
hv_get_next_readlocation_withoffset(inring_info, offset);
next_read_location = hv_copyfrom_ringbuffer(inring_info,
buffer,
packetlen,
next_read_location);
next_read_location = hv_copyfrom_ringbuffer(inring_info,
&prev_indices,
sizeof(u64),
next_read_location);
/*
* 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.
*/
mb();
/* Update the read index */
hv_set_next_read_location(inring_info, next_read_location);
*signal = hv_need_to_signal_on_read(inring_info);
out_unlock:
spin_unlock_irqrestore(&inring_info->ring_lock, flags);
return ret;
}
