/**
* vfs_lib_ring_buffer_ioctl - control ring buffer reader synchronization
*
* @filp: the file
* @cmd: the command
* @arg: command arg
*
* This ioctl implements commands necessary for producer/consumer
* and flight recorder reader interaction :
* RING_BUFFER_GET_NEXT_SUBBUF
* Get the next sub-buffer that can be read. It never blocks.
* RING_BUFFER_PUT_NEXT_SUBBUF
* Release the currently read sub-buffer.
* RING_BUFFER_GET_SUBBUF_SIZE
* returns the size of the current sub-buffer.
* RING_BUFFER_GET_MAX_SUBBUF_SIZE
* returns the maximum size for sub-buffers.
* RING_BUFFER_GET_NUM_SUBBUF
* returns the number of reader-visible sub-buffers in the per cpu
* channel (for mmap).
* RING_BUFFER_GET_MMAP_READ_OFFSET
* returns the offset of the subbuffer belonging to the reader.
* Should only be used for mmap clients.
*/
static
long vfs_lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct lib_ring_buffer *buf = filp->private_data;
return lib_ring_buffer_ioctl(filp, cmd, arg, buf);
}
static
long lttng_metadata_ring_buffer_ioctl(struct file *filp,
unsigned int cmd, unsigned long arg)
{
int ret;
struct lttng_metadata_stream *stream = filp->private_data;
struct lib_ring_buffer *buf = stream->priv;
switch (cmd) {
case RING_BUFFER_GET_NEXT_SUBBUF:
{
struct lttng_metadata_stream *stream = filp->private_data;
struct lib_ring_buffer *buf = stream->priv;
struct channel *chan = buf->backend.chan;
ret = lttng_metadata_output_channel(stream, chan);
if (ret > 0) {
lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE);
ret = 0;
} else if (ret < 0)
goto err;
break;
}
case RING_BUFFER_GET_SUBBUF:
{
/*
* Random access is not allowed for metadata channel.
*/
return -ENOSYS;
}
case RING_BUFFER_FLUSH:
{
struct lttng_metadata_stream *stream = filp->private_data;
struct lib_ring_buffer *buf = stream->priv;
struct channel *chan = buf->backend.chan;
/*
* Before doing the actual ring buffer flush, write up to one
* packet of metadata in the ring buffer.
*/
ret = lttng_metadata_output_channel(stream, chan);
if (ret < 0)
goto err;
break;
}
case RING_BUFFER_GET_METADATA_VERSION:
{
struct lttng_metadata_stream *stream = filp->private_data;
return put_u64(stream->version, arg);
}
default:
break;
}
/* PUT_SUBBUF is the one from lib ring buffer, unmodified. */
/* Performing lib ring buffer ioctl after our own. */
ret = lib_ring_buffer_ioctl(filp, cmd, arg, buf);
if (ret < 0)
goto err;
switch (cmd) {
case RING_BUFFER_PUT_NEXT_SUBBUF:
{
lttng_metadata_ring_buffer_ioctl_put_next_subbuf(filp,
cmd, arg);
break;
}
default:
break;
}
err:
return ret;
}
