lib/ringbuffer/vfs.h

   1 #ifndef _LINUX_RING_BUFFER_VFS_H
   2 #define _LINUX_RING_BUFFER_VFS_H
   3
   4 /*
   5  * linux/ringbuffer/vfs.h
   6  *
   7  * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * Wait-free ring buffer VFS file operations.
  10  *
  11  * Author:
  12  *      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  13  *
  14  * Dual LGPL v2.1/GPL v2 license.
  15  */
  16
  17 #include <linux/fs.h>
  18 #include <linux/poll.h>
  19
  20 /* VFS API */
  21
  22 extern const struct file_operations lib_ring_buffer_file_operations;
  23
  24 /*
  25  * Internal file operations.
  26  */
  27
  28 int lib_ring_buffer_open(struct inode *inode, struct file *file);
  29 int lib_ring_buffer_release(struct inode *inode, struct file *file);
  30 unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait);
  31 ssize_t lib_ring_buffer_splice_read(struct file *in, loff_t *ppos,
  32                                     struct pipe_inode_info *pipe, size_t len,
  33                                     unsigned int flags);
  34 int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma);
  35
  36 /* Ring Buffer ioctl() and ioctl numbers */
  37 long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
  38 #ifdef CONFIG_COMPAT
  39 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
  40                                   unsigned long arg);
  41 #endif
  42
  43 /*
  44  * Use RING_BUFFER_GET_NEXT_SUBBUF / RING_BUFFER_PUT_NEXT_SUBBUF to read and
  45  * consume sub-buffers sequentially.
  46  *
  47  * Reading sub-buffers without consuming them can be performed with:
  48  *
  49  * RING_BUFFER_SNAPSHOT
  50  * RING_BUFFER_SNAPSHOT_GET_CONSUMED
  51  * RING_BUFFER_SNAPSHOT_GET_PRODUCED
  52  *
  53  * to get the offset range to consume, and then by passing each sub-buffer
  54  * offset to RING_BUFFER_GET_SUBBUF, read the sub-buffer, and then release it
  55  * with RING_BUFFER_PUT_SUBBUF.
  56  *
  57  * Note that the "snapshot" API can be used to read the sub-buffer in reverse
  58  * order, which is useful for flight recorder snapshots.
  59  */
  60
  61 /* Get a snapshot of the current ring buffer producer and consumer positions */
  62 #define RING_BUFFER_SNAPSHOT                    _IO(0xF6, 0x00)
  63 /* Get the consumer position (iteration start) */
  64 #define RING_BUFFER_SNAPSHOT_GET_CONSUMED       _IOR(0xF6, 0x01, unsigned long)
  65 /* Get the producer position (iteration end) */
  66 #define RING_BUFFER_SNAPSHOT_GET_PRODUCED       _IOR(0xF6, 0x02, unsigned long)
  67 /* Get exclusive read access to the specified sub-buffer position */
  68 #define RING_BUFFER_GET_SUBBUF                  _IOW(0xF6, 0x03, unsigned long)
  69 /* Release exclusive sub-buffer access */
  70 #define RING_BUFFER_PUT_SUBBUF                  _IO(0xF6, 0x04)
  71
  72 /* Get exclusive read access to the next sub-buffer that can be read. */
  73 #define RING_BUFFER_GET_NEXT_SUBBUF             _IO(0xF6, 0x05)
  74 /* Release exclusive sub-buffer access, move consumer forward. */
  75 #define RING_BUFFER_PUT_NEXT_SUBBUF             _IO(0xF6, 0x06)
  76 /* returns the size of the current sub-buffer, without padding (for mmap). */
  77 #define RING_BUFFER_GET_SUBBUF_SIZE             _IOR(0xF6, 0x07, unsigned long)
  78 /* returns the size of the current sub-buffer, with padding (for splice). */
  79 #define RING_BUFFER_GET_PADDED_SUBBUF_SIZE      _IOR(0xF6, 0x08, unsigned long)
  80 /* returns the maximum size for sub-buffers. */
  81 #define RING_BUFFER_GET_MAX_SUBBUF_SIZE         _IOR(0xF6, 0x09, unsigned long)
  82 /* returns the length to mmap. */
  83 #define RING_BUFFER_GET_MMAP_LEN                _IOR(0xF6, 0x0A, unsigned long)
  84 /* returns the offset of the subbuffer belonging to the mmap reader. */
  85 #define RING_BUFFER_GET_MMAP_READ_OFFSET        _IOR(0xF6, 0x0B, unsigned long)
  86
  87 #endif /* _LINUX_RING_BUFFER_VFS_H */