-#ifndef _LIB_RING_BUFFER_FRONTEND_INTERNAL_H
-#define _LIB_RING_BUFFER_FRONTEND_INTERNAL_H
-
-/*
+/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
+ *
* linux/ringbuffer/frontend_internal.h
*
* Ring Buffer Library Synchronization Header (internal helpers).
*
* Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- *
- * Author:
- * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
* See ring_buffer_frontend.c for more information on wait-free algorithms.
*/
+#ifndef _LIB_RING_BUFFER_FRONTEND_INTERNAL_H
+#define _LIB_RING_BUFFER_FRONTEND_INTERNAL_H
+
#include <wrapper/ringbuffer/config.h>
#include <wrapper/ringbuffer/backend_types.h>
#include <wrapper/ringbuffer/frontend_types.h>
void lib_ring_buffer_switch_remote(struct lib_ring_buffer *buf);
extern
void lib_ring_buffer_switch_remote_empty(struct lib_ring_buffer *buf);
+extern
+void lib_ring_buffer_clear(struct lib_ring_buffer *buf);
/* Buffer write helpers */
consumed_new) != consumed_old));
}
+/*
+ * Move consumed position to the beginning of subbuffer in which the
+ * write offset is. Should only be used on ring buffers that are not
+ * actively being written into, because clear_reader does not take into
+ * account the commit counters when moving the consumed position, which
+ * can make concurrent trace producers or consumers observe consumed
+ * position further than the write offset, which breaks ring buffer
+ * algorithm guarantees.
+ */
+static inline
+void lib_ring_buffer_clear_reader(struct lib_ring_buffer *buf,
+ struct channel *chan)
+{
+ const struct lib_ring_buffer_config *config = &chan->backend.config;
+ unsigned long offset, consumed_old, consumed_new;
+
+ do {
+ offset = v_read(config, &buf->offset);
+ consumed_old = atomic_long_read(&buf->consumed);
+ CHAN_WARN_ON(chan, (long) (subbuf_trunc(offset, chan)
+ - subbuf_trunc(consumed_old, chan))
+ < 0);
+ consumed_new = subbuf_trunc(offset, chan);
+ } while (unlikely(atomic_long_cmpxchg(&buf->consumed, consumed_old,
+ consumed_new) != consumed_old));
+}
+
static inline
int lib_ring_buffer_pending_data(const struct lib_ring_buffer_config *config,
struct lib_ring_buffer *buf,