Import lib ring buffer into LTTng modules

[lttng-modules.git] / lib / ringbuffer / vfs.h

diff --git a/lib/ringbuffer/vfs.h b/lib/ringbuffer/vfs.h
new file mode 100644 (file)
index 0000000..0a09637
--- /dev/null
+++ b/lib/ringbuffer/vfs.h
@@ -0,0 +1,87 @@
+#ifndef _LINUX_RING_BUFFER_VFS_H
+#define _LINUX_RING_BUFFER_VFS_H
+
+/*
+ * linux/ringbuffer/vfs.h
+ *
+ * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Wait-free ring buffer VFS file operations.
+ *
+ * Author:
+ *     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/fs.h>
+#include <linux/poll.h>
+
+/* VFS API */
+
+extern const struct file_operations lib_ring_buffer_file_operations;
+
+/*
+ * Internal file operations.
+ */
+
+int lib_ring_buffer_open(struct inode *inode, struct file *file);
+int lib_ring_buffer_release(struct inode *inode, struct file *file);
+unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait);
+ssize_t lib_ring_buffer_splice_read(struct file *in, loff_t *ppos,
+                                   struct pipe_inode_info *pipe, size_t len,
+                                   unsigned int flags);
+int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma);
+
+/* Ring Buffer ioctl() and ioctl numbers */
+long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
+#ifdef CONFIG_COMPAT
+long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
+                                 unsigned long arg);
+#endif
+
+/*
+ * Use RING_BUFFER_GET_NEXT_SUBBUF / RING_BUFFER_PUT_NEXT_SUBBUF to read and
+ * consume sub-buffers sequentially.
+ *
+ * Reading sub-buffers without consuming them can be performed with:
+ *
+ * RING_BUFFER_SNAPSHOT
+ * RING_BUFFER_SNAPSHOT_GET_CONSUMED
+ * RING_BUFFER_SNAPSHOT_GET_PRODUCED
+ *
+ * to get the offset range to consume, and then by passing each sub-buffer
+ * offset to RING_BUFFER_GET_SUBBUF, read the sub-buffer, and then release it
+ * with RING_BUFFER_PUT_SUBBUF.
+ *
+ * Note that the "snapshot" API can be used to read the sub-buffer in reverse
+ * order, which is useful for flight recorder snapshots.
+ */
+
+/* Get a snapshot of the current ring buffer producer and consumer positions */
+#define RING_BUFFER_SNAPSHOT                   _IO(0xF6, 0x00)
+/* Get the consumer position (iteration start) */
+#define RING_BUFFER_SNAPSHOT_GET_CONSUMED      _IOR(0xF6, 0x01, unsigned long)
+/* Get the producer position (iteration end) */
+#define RING_BUFFER_SNAPSHOT_GET_PRODUCED      _IOR(0xF6, 0x02, unsigned long)
+/* Get exclusive read access to the specified sub-buffer position */
+#define RING_BUFFER_GET_SUBBUF                 _IOW(0xF6, 0x03, unsigned long)
+/* Release exclusive sub-buffer access */
+#define RING_BUFFER_PUT_SUBBUF                 _IO(0xF6, 0x04)
+
+/* Get exclusive read access to the next sub-buffer that can be read. */
+#define RING_BUFFER_GET_NEXT_SUBBUF            _IO(0xF6, 0x05)
+/* Release exclusive sub-buffer access, move consumer forward. */
+#define RING_BUFFER_PUT_NEXT_SUBBUF            _IO(0xF6, 0x06)
+/* returns the size of the current sub-buffer, without padding (for mmap). */
+#define RING_BUFFER_GET_SUBBUF_SIZE            _IOR(0xF6, 0x07, unsigned long)
+/* returns the size of the current sub-buffer, with padding (for splice). */
+#define RING_BUFFER_GET_PADDED_SUBBUF_SIZE     _IOR(0xF6, 0x08, unsigned long)
+/* returns the maximum size for sub-buffers. */
+#define RING_BUFFER_GET_MAX_SUBBUF_SIZE                _IOR(0xF6, 0x09, unsigned long)
+/* returns the length to mmap. */
+#define RING_BUFFER_GET_MMAP_LEN               _IOR(0xF6, 0x0A, unsigned long)
+/* returns the offset of the subbuffer belonging to the mmap reader. */
+#define RING_BUFFER_GET_MMAP_READ_OFFSET       _IOR(0xF6, 0x0B, unsigned long)
+
+#endif /* _LINUX_RING_BUFFER_VFS_H */