/**
* lttng_metadata_ring_buffer_poll - LTTng ring buffer poll file operation
* @filp: the file
* @wait: poll table
*
* Handles the poll operations for the metadata channels.
*/
static
unsigned int lttng_metadata_ring_buffer_poll(struct file *filp,
poll_table *wait)
{
struct lttng_metadata_stream *stream = filp->private_data;
struct lib_ring_buffer *buf = stream->priv;
int finalized;
unsigned int mask = 0;
if (filp->f_mode & FMODE_READ) {
poll_wait_set_exclusive(wait);
poll_wait(filp, &stream->read_wait, wait);
finalized = stream->finalized;
/*
* lib_ring_buffer_is_finalized() contains a smp_rmb()
* ordering finalized load before offsets loads.
*/
WARN_ON(atomic_long_read(&buf->active_readers) != 1);
if (finalized)
mask |= POLLHUP;
mutex_lock(&stream->metadata_cache->lock);
if (stream->metadata_cache->metadata_written >
stream->metadata_out)
mask |= POLLIN;
mutex_unlock(&stream->metadata_cache->lock);
}
return mask;
}
unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait,
struct lib_ring_buffer *buf)
{
unsigned int mask = 0;
struct channel *chan = buf->backend.chan;
const struct lib_ring_buffer_config *config = &chan->backend.config;
int finalized, disabled;
if (filp->f_mode & FMODE_READ) {
poll_wait_set_exclusive(wait);
poll_wait(filp, &buf->read_wait, wait);
finalized = lib_ring_buffer_is_finalized(config, buf);
disabled = lib_ring_buffer_channel_is_disabled(chan);
/*
* lib_ring_buffer_is_finalized() contains a smp_rmb() ordering
* finalized load before offsets loads.
*/
WARN_ON(atomic_long_read(&buf->active_readers) != 1);
retry:
if (disabled)
return POLLERR;
if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf), chan)
- subbuf_trunc(lib_ring_buffer_get_consumed(config, buf), chan)
== 0) {
if (finalized)
return POLLHUP;
else {
/*
* The memory barriers
* __wait_event()/wake_up_interruptible() take
* care of "raw_spin_is_locked" memory ordering.
*/
if (raw_spin_is_locked(&buf->raw_tick_nohz_spinlock))
goto retry;
else
return 0;
}
} else {
if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf),
chan)
- subbuf_trunc(lib_ring_buffer_get_consumed(config, buf),
chan)
>= chan->backend.buf_size)
return POLLPRI | POLLRDBAND;
else
return POLLIN | POLLRDNORM;
}
}
return mask;
}
/**
* lttng_channel_poll - lttng stream addition/removal monitoring
*
* @file: the file
* @wait: poll table
*/
unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
{
struct lttng_channel *channel = file->private_data;
unsigned int mask = 0;
if (file->f_mode & FMODE_READ) {
poll_wait_set_exclusive(wait);
poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
wait);
if (channel->ops->is_disabled(channel->chan))
return POLLERR;
if (channel->ops->is_finalized(channel->chan))
return POLLHUP;
if (channel->ops->buffer_has_read_closed_stream(channel->chan))
return POLLIN | POLLRDNORM;
return 0;
}
return mask;
}
