libringbuffer/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 /* VFS API */
  18
  19 extern const struct file_operations lib_ring_buffer_file_operations;
  20
  21 /*
  22  * Internal file operations.
  23  */
  24
  25 int lib_ring_buffer_open(struct inode *inode, struct file *file);
  26 int lib_ring_buffer_release(struct inode *inode, struct file *file);
  27 unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait);
  28 ssize_t lib_ring_buffer_splice_read(struct file *in, loff_t *ppos,
  29                                     struct pipe_inode_info *pipe, size_t len,
  30                                     unsigned int flags);
  31 int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma);
  32
  33 /* Ring Buffer ioctl() and ioctl numbers */
  34 long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
  35 #ifdef CONFIG_COMPAT
  36 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
  37                                   unsigned long arg);
  38 #endif
  39
  40 /*
  41  * Use RING_BUFFER_GET_NEXT_SUBBUF / RING_BUFFER_PUT_NEXT_SUBBUF to read and
  42  * consume sub-buffers sequentially.
  43  *
  44  * Reading sub-buffers without consuming them can be performed with:
  45  *
  46  * RING_BUFFER_SNAPSHOT
  47  * RING_BUFFER_SNAPSHOT_GET_CONSUMED
  48  * RING_BUFFER_SNAPSHOT_GET_PRODUCED
  49  *
  50  * to get the offset range to consume, and then by passing each sub-buffer
  51  * offset to RING_BUFFER_GET_SUBBUF, read the sub-buffer, and then release it
  52  * with RING_BUFFER_PUT_SUBBUF.
  53  *
  54  * Note that the "snapshot" API can be used to read the sub-buffer in reverse
  55  * order, which is useful for flight recorder snapshots.
  56  */
  57
  58 /* Get a snapshot of the current ring buffer producer and consumer positions */
  59 #define RING_BUFFER_SNAPSHOT                    _IO(0xF6, 0x00)
  60 /* Get the consumer position (iteration start) */
  61 #define RING_BUFFER_SNAPSHOT_GET_CONSUMED       _IOR(0xF6, 0x01, unsigned long)
  62 /* Get the producer position (iteration end) */
  63 #define RING_BUFFER_SNAPSHOT_GET_PRODUCED       _IOR(0xF6, 0x02, unsigned long)
  64 /* Get exclusive read access to the specified sub-buffer position */
  65 #define RING_BUFFER_GET_SUBBUF                  _IOW(0xF6, 0x03, unsigned long)
  66 /* Release exclusive sub-buffer access */
  67 #define RING_BUFFER_PUT_SUBBUF                  _IO(0xF6, 0x04)
  68
  69 /* Get exclusive read access to the next sub-buffer that can be read. */
  70 #define RING_BUFFER_GET_NEXT_SUBBUF             _IO(0xF6, 0x05)
  71 /* Release exclusive sub-buffer access, move consumer forward. */
  72 #define RING_BUFFER_PUT_NEXT_SUBBUF             _IO(0xF6, 0x06)
  73 /* returns the size of the current sub-buffer, without padding (for mmap). */
  74 #define RING_BUFFER_GET_SUBBUF_SIZE             _IOR(0xF6, 0x07, unsigned long)
  75 /* returns the size of the current sub-buffer, with padding (for splice). */
  76 #define RING_BUFFER_GET_PADDED_SUBBUF_SIZE      _IOR(0xF6, 0x08, unsigned long)
  77 /* returns the maximum size for sub-buffers. */
  78 #define RING_BUFFER_GET_MAX_SUBBUF_SIZE         _IOR(0xF6, 0x09, unsigned long)
  79 /* returns the length to mmap. */
  80 #define RING_BUFFER_GET_MMAP_LEN                _IOR(0xF6, 0x0A, unsigned long)
  81 /* returns the offset of the subbuffer belonging to the mmap reader. */
  82 #define RING_BUFFER_GET_MMAP_READ_OFFSET        _IOR(0xF6, 0x0B, unsigned long)
  83 /* flush the current sub-buffer */
  84 #define RING_BUFFER_FLUSH                       _IO(0xF6, 0x0C)
  85
  86 #endif /* _LINUX_RING_BUFFER_VFS_H */