#include <linux/module.h>
#include <linux/percpu.h>
-#include "../../wrapper/ringbuffer/config.h"
-#include "../../wrapper/ringbuffer/backend.h"
-#include "../../wrapper/ringbuffer/frontend.h"
-#include "../../wrapper/ringbuffer/iterator.h"
-#include "../../wrapper/ringbuffer/nohz.h"
+#include <wrapper/ringbuffer/config.h>
+#include <wrapper/ringbuffer/backend.h>
+#include <wrapper/ringbuffer/frontend.h>
+#include <wrapper/ringbuffer/iterator.h>
+#include <wrapper/ringbuffer/nohz.h>
+#include <wrapper/atomic.h>
+#include <wrapper/kref.h>
+#include <wrapper/percpu-defs.h>
/*
* Internal structure representing offsets to use at a sub-buffer switch.
struct switch_offsets {
unsigned long begin, end, old;
size_t pre_header_padding, size;
- unsigned int switch_new_start:1, switch_old_start:1, switch_old_end:1;
+ unsigned int switch_new_start:1, switch_new_end:1, switch_old_start:1,
+ switch_old_end:1;
};
#ifdef CONFIG_NO_HZ
raw_spin_unlock(&buf->raw_tick_nohz_spinlock);
break;
case TICK_NOHZ_STOP:
- spin_lock(&__get_cpu_var(ring_buffer_nohz_lock));
+ spin_lock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
lib_ring_buffer_stop_switch_timer(buf);
lib_ring_buffer_stop_read_timer(buf);
- spin_unlock(&__get_cpu_var(ring_buffer_nohz_lock));
+ spin_unlock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
break;
case TICK_NOHZ_RESTART:
- spin_lock(&__get_cpu_var(ring_buffer_nohz_lock));
+ spin_lock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
lib_ring_buffer_start_read_timer(buf);
lib_ring_buffer_start_switch_timer(buf);
- spin_unlock(&__get_cpu_var(ring_buffer_nohz_lock));
+ spin_unlock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
break;
}
static void channel_free(struct channel *chan)
{
+ if (chan->backend.release_priv_ops) {
+ chan->backend.release_priv_ops(chan->backend.priv_ops);
+ }
channel_iterator_free(chan);
channel_backend_free(&chan->backend);
kfree(chan);
if (!atomic_long_add_unless(&buf->active_readers, 1, 1))
return -EBUSY;
- kref_get(&chan->ref);
- smp_mb__after_atomic_inc();
+ if (!lttng_kref_get(&chan->ref)) {
+ atomic_long_dec(&buf->active_readers);
+ return -EOVERFLOW;
+ }
+ lttng_smp_mb__after_atomic();
return 0;
}
EXPORT_SYMBOL_GPL(lib_ring_buffer_open_read);
struct channel *chan = buf->backend.chan;
CHAN_WARN_ON(chan, atomic_long_read(&buf->active_readers) != 1);
- smp_mb__before_atomic_dec();
+ lttng_smp_mb__before_atomic();
atomic_long_dec(&buf->active_readers);
kref_put(&chan->ref, channel_release);
}
*/
if (((commit_count - chan->backend.subbuf_size)
& chan->commit_count_mask)
- - (buf_trunc(consumed_cur, chan)
+ - (buf_trunc(consumed, chan)
>> chan->backend.num_subbuf_order)
!= 0)
goto nodata;
* Check that we are not about to read the same subbuffer in
* which the writer head is.
*/
- if (subbuf_trunc(write_offset, chan) - subbuf_trunc(consumed_cur, chan)
+ if (subbuf_trunc(write_offset, chan) - subbuf_trunc(consumed, chan)
== 0)
goto nodata;
commit_count = v_read(config, &buf->commit_hot[oldidx].cc);
/* Check if the written buffer has to be delivered */
lib_ring_buffer_check_deliver(config, buf, chan, offsets->old,
- commit_count, oldidx);
+ commit_count, oldidx, tsc);
lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx,
- offsets->old, commit_count,
- config->cb.subbuffer_header_size());
+ offsets->old + config->cb.subbuffer_header_size(),
+ commit_count);
}
/*
v_add(config, padding_size, &buf->commit_hot[oldidx].cc);
commit_count = v_read(config, &buf->commit_hot[oldidx].cc);
lib_ring_buffer_check_deliver(config, buf, chan, offsets->old - 1,
- commit_count, oldidx);
+ commit_count, oldidx, tsc);
lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx,
- offsets->old, commit_count,
- padding_size);
+ offsets->old + padding_size, commit_count);
}
/*
commit_count = v_read(config, &buf->commit_hot[beginidx].cc);
/* Check if the written buffer has to be delivered */
lib_ring_buffer_check_deliver(config, buf, chan, offsets->begin,
- commit_count, beginidx);
+ commit_count, beginidx, tsc);
lib_ring_buffer_write_commit_counter(config, buf, chan, beginidx,
- offsets->begin, commit_count,
- config->cb.subbuffer_header_size());
+ offsets->begin + config->cb.subbuffer_header_size(),
+ commit_count);
+}
+
+/*
+ * lib_ring_buffer_switch_new_end: finish switching current subbuffer
+ *
+ * Calls subbuffer_set_data_size() to set the data size of the current
+ * sub-buffer. We do not need to perform check_deliver nor commit here,
+ * since this task will be done by the "commit" of the event for which
+ * we are currently doing the space reservation.
+ */
+static
+void lib_ring_buffer_switch_new_end(struct lib_ring_buffer *buf,
+ struct channel *chan,
+ struct switch_offsets *offsets,
+ u64 tsc)
+{
+ const struct lib_ring_buffer_config *config = &chan->backend.config;
+ unsigned long endidx, data_size;
+
+ endidx = subbuf_index(offsets->end - 1, chan);
+ data_size = subbuf_offset(offsets->end - 1, chan) + 1;
+ subbuffer_set_data_size(config, &buf->backend, endidx, data_size);
}
/*
u64 *tsc)
{
const struct lib_ring_buffer_config *config = &chan->backend.config;
- unsigned long off;
+ unsigned long off, reserve_commit_diff;
offsets->begin = v_read(config, &buf->offset);
offsets->old = offsets->begin;
* (records and header timestamps) are visible to the reader. This is
* required for quiescence guarantees for the fusion merge.
*/
- if (mode == SWITCH_FLUSH || off > 0) {
- if (unlikely(off == 0)) {
- /*
- * A final flush that encounters an empty
- * sub-buffer cannot switch buffer if a
- * reader is located within this sub-buffer.
- * Anyway, the purpose of final flushing of a
- * sub-buffer at offset 0 is to handle the case
- * of entirely empty stream.
- */
- if (unlikely(subbuf_trunc(offsets->begin, chan)
- - subbuf_trunc((unsigned long)
- atomic_long_read(&buf->consumed), chan)
- >= chan->backend.buf_size))
- return -1;
- /*
- * The client does not save any header information.
- * Don't switch empty subbuffer on finalize, because it
- * is invalid to deliver a completely empty subbuffer.
- */
- if (!config->cb.subbuffer_header_size())
+ if (mode != SWITCH_FLUSH && !off)
+ return -1; /* we do not have to switch : buffer is empty */
+
+ if (unlikely(off == 0)) {
+ unsigned long sb_index, commit_count;
+
+ /*
+ * We are performing a SWITCH_FLUSH. At this stage, there are no
+ * concurrent writes into the buffer.
+ *
+ * The client does not save any header information. Don't
+ * switch empty subbuffer on finalize, because it is invalid to
+ * deliver a completely empty subbuffer.
+ */
+ if (!config->cb.subbuffer_header_size())
+ return -1;
+
+ /* Test new buffer integrity */
+ sb_index = subbuf_index(offsets->begin, chan);
+ commit_count = v_read(config,
+ &buf->commit_cold[sb_index].cc_sb);
+ reserve_commit_diff =
+ (buf_trunc(offsets->begin, chan)
+ >> chan->backend.num_subbuf_order)
+ - (commit_count & chan->commit_count_mask);
+ if (likely(reserve_commit_diff == 0)) {
+ /* Next subbuffer not being written to. */
+ if (unlikely(config->mode != RING_BUFFER_OVERWRITE &&
+ subbuf_trunc(offsets->begin, chan)
+ - subbuf_trunc((unsigned long)
+ atomic_long_read(&buf->consumed), chan)
+ >= chan->backend.buf_size)) {
+ /*
+ * We do not overwrite non consumed buffers
+ * and we are full : don't switch.
+ */
return -1;
+ } else {
+ /*
+ * Next subbuffer not being written to, and we
+ * are either in overwrite mode or the buffer is
+ * not full. It's safe to write in this new
+ * subbuffer.
+ */
+ }
+ } else {
/*
- * Need to write the subbuffer start header on finalize.
+ * Next subbuffer reserve offset does not match the
+ * commit offset. Don't perform switch in
+ * producer-consumer and overwrite mode. Caused by
+ * either a writer OOPS or too many nested writes over a
+ * reserve/commit pair.
*/
- offsets->switch_old_start = 1;
+ return -1;
}
- offsets->begin = subbuf_align(offsets->begin, chan);
- } else
- return -1; /* we do not have to switch : buffer is empty */
+
+ /*
+ * Need to write the subbuffer start header on finalize.
+ */
+ offsets->switch_old_start = 1;
+ }
+ offsets->begin = subbuf_align(offsets->begin, chan);
/* Note: old points to the next subbuf at offset 0 */
offsets->end = offsets->begin;
return 0;
struct lib_ring_buffer_ctx *ctx)
{
const struct lib_ring_buffer_config *config = &chan->backend.config;
- unsigned long reserve_commit_diff;
+ unsigned long reserve_commit_diff, offset_cmp;
- offsets->begin = v_read(config, &buf->offset);
+retry:
+ offsets->begin = offset_cmp = v_read(config, &buf->offset);
offsets->old = offsets->begin;
offsets->switch_new_start = 0;
+ offsets->switch_new_end = 0;
offsets->switch_old_end = 0;
offsets->pre_header_padding = 0;
}
}
if (unlikely(offsets->switch_new_start)) {
- unsigned long sb_index;
+ unsigned long sb_index, commit_count;
/*
* We are typically not filling the previous buffer completely.
+ config->cb.subbuffer_header_size();
/* Test new buffer integrity */
sb_index = subbuf_index(offsets->begin, chan);
+ /*
+ * Read buf->offset before buf->commit_cold[sb_index].cc_sb.
+ * lib_ring_buffer_check_deliver() has the matching
+ * memory barriers required around commit_cold cc_sb
+ * updates to ensure reserve and commit counter updates
+ * are not seen reordered when updated by another CPU.
+ */
+ smp_rmb();
+ commit_count = v_read(config,
+ &buf->commit_cold[sb_index].cc_sb);
+ /* Read buf->commit_cold[sb_index].cc_sb before buf->offset. */
+ smp_rmb();
+ if (unlikely(offset_cmp != v_read(config, &buf->offset))) {
+ /*
+ * The reserve counter have been concurrently updated
+ * while we read the commit counter. This means the
+ * commit counter we read might not match buf->offset
+ * due to concurrent update. We therefore need to retry.
+ */
+ goto retry;
+ }
reserve_commit_diff =
(buf_trunc(offsets->begin, chan)
>> chan->backend.num_subbuf_order)
- - ((unsigned long) v_read(config,
- &buf->commit_cold[sb_index].cc_sb)
- & chan->commit_count_mask);
+ - (commit_count & chan->commit_count_mask);
if (likely(reserve_commit_diff == 0)) {
/* Next subbuffer not being written to. */
if (unlikely(config->mode != RING_BUFFER_OVERWRITE &&
} else {
/*
* Next subbuffer reserve offset does not match the
- * commit offset. Drop record in producer-consumer and
- * overwrite mode. Caused by either a writer OOPS or too
- * many nested writes over a reserve/commit pair.
+ * commit offset, and this did not involve update to the
+ * reserve counter. Drop record in producer-consumer and
+ * overwrite mode. Caused by either a writer OOPS or
+ * too many nested writes over a reserve/commit pair.
*/
v_inc(config, &buf->records_lost_wrap);
return -EIO;
*/
}
offsets->end = offsets->begin + offsets->size;
+
+ if (unlikely(subbuf_offset(offsets->end, chan) == 0)) {
+ /*
+ * The offset_end will fall at the very beginning of the next
+ * subbuffer.
+ */
+ offsets->switch_new_end = 1; /* For offsets->begin */
+ }
return 0;
}
if (unlikely(offsets.switch_new_start))
lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx->tsc);
+ if (unlikely(offsets.switch_new_end))
+ lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx->tsc);
+
ctx->slot_size = offsets.size;
ctx->pre_offset = offsets.begin;
ctx->buf_offset = offsets.begin + offsets.pre_header_padding;