2 * linux/include/linux/relayfs_fs.h
4 * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
5 * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
7 * RelayFS definitions and declarations
10 #ifndef _LINUX_RELAYFS_FS_H
11 #define _LINUX_RELAYFS_FS_H
13 #include <linux/config.h>
14 #include <linux/types.h>
15 #include <linux/sched.h>
16 #include <linux/wait.h>
17 #include <linux/list.h>
19 #include <linux/poll.h>
20 #include <linux/kref.h>
23 * Tracks changes to rchan/rchan_buf structs
25 #define RELAYFS_CHANNEL_VERSION 6
28 * Per-cpu relay channel buffer
32 void *start
; /* start of channel buffer */
33 void *data
; /* start of current sub-buffer */
34 size_t offset
; /* current offset into sub-buffer */
35 size_t subbufs_produced
; /* count of sub-buffers produced */
36 size_t subbufs_consumed
; /* count of sub-buffers consumed */
37 struct rchan
*chan
; /* associated channel */
38 wait_queue_head_t read_wait
; /* reader wait queue */
39 struct work_struct wake_readers
; /* reader wake-up work struct */
40 struct dentry
*dentry
; /* channel file dentry */
41 struct kref kref
; /* channel buffer refcount */
42 struct page
**page_array
; /* array of current buffer pages */
43 unsigned int page_count
; /* number of current buffer pages */
44 unsigned int finalized
; /* buffer has been finalized */
45 size_t *padding
; /* padding counts per sub-buffer */
46 size_t prev_padding
; /* temporary variable */
47 size_t bytes_consumed
; /* bytes consumed in cur read subbuf */
48 unsigned int cpu
; /* this buf's cpu */
49 } ____cacheline_aligned
;
52 * Relay channel data structure
56 u32 version
; /* the version of this struct */
57 size_t subbuf_size
; /* sub-buffer size */
58 size_t n_subbufs
; /* number of sub-buffers per buffer */
59 size_t alloc_size
; /* total buffer size allocated */
60 struct rchan_callbacks
*cb
; /* client callbacks */
61 struct kref kref
; /* channel refcount */
62 void *private_data
; /* for user-defined data */
63 size_t last_toobig
; /* tried to log event > subbuf size */
64 struct rchan_buf
*buf
[NR_CPUS
]; /* per-cpu channel buffers */
70 struct relayfs_inode_info
72 struct inode vfs_inode
;
73 struct rchan_buf
*buf
;
76 static inline struct relayfs_inode_info
*RELAYFS_I(struct inode
*inode
)
78 return container_of(inode
, struct relayfs_inode_info
, vfs_inode
);
82 * Relay channel client callbacks
84 struct rchan_callbacks
87 * subbuf_start - called on buffer-switch to a new sub-buffer
88 * @buf: the channel buffer containing the new sub-buffer
89 * @subbuf: the start of the new sub-buffer
90 * @prev_subbuf: the start of the previous sub-buffer
91 * @prev_padding: unused space at the end of previous sub-buffer
93 * The client should return 1 to continue logging, 0 to stop
96 * NOTE: subbuf_start will also be invoked when the buffer is
97 * created, so that the first sub-buffer can be initialized
98 * if necessary. In this case, prev_subbuf will be NULL.
100 * NOTE: the client can reserve bytes at the beginning of the new
101 * sub-buffer by calling subbuf_start_reserve() in this callback.
103 int (*subbuf_start
) (struct rchan_buf
*buf
,
106 size_t prev_padding
);
109 * buf_mapped - relayfs buffer mmap notification
110 * @buf: the channel buffer
111 * @filp: relayfs file pointer
113 * Called when a relayfs file is successfully mmapped
115 void (*buf_mapped
)(struct rchan_buf
*buf
,
119 * buf_unmapped - relayfs buffer unmap notification
120 * @buf: the channel buffer
121 * @filp: relayfs file pointer
123 * Called when a relayfs file is successfully unmapped
125 void (*buf_unmapped
)(struct rchan_buf
*buf
,
130 * relayfs kernel API, fs/relayfs/relay.c
133 struct rchan
*relay_open(const char *base_filename
,
134 struct dentry
*parent
,
137 struct rchan_callbacks
*cb
);
138 extern void relay_close(struct rchan
*chan
);
139 extern void relay_flush(struct rchan
*chan
);
140 extern void relay_subbufs_consumed(struct rchan
*chan
,
143 extern void relay_reset(struct rchan
*chan
);
144 extern int relay_buf_full(struct rchan_buf
*buf
);
146 extern size_t relay_switch_subbuf(struct rchan_buf
*buf
,
148 extern struct dentry
*relayfs_create_dir(const char *name
,
149 struct dentry
*parent
);
150 extern int relayfs_remove_dir(struct dentry
*dentry
);
153 * relay_write - write data into the channel
154 * @chan: relay channel
155 * @data: data to be written
156 * @length: number of bytes to write
158 * Writes data into the current cpu's channel buffer.
160 * Protects the buffer by disabling interrupts. Use this
161 * if you might be logging from interrupt context. Try
162 * __relay_write() if you know you won't be logging from
165 static inline void relay_write(struct rchan
*chan
,
170 struct rchan_buf
*buf
;
172 local_irq_save(flags
);
173 buf
= chan
->buf
[smp_processor_id()];
174 if (unlikely(buf
->offset
+ length
> chan
->subbuf_size
))
175 length
= relay_switch_subbuf(buf
, length
);
176 memcpy(buf
->data
+ buf
->offset
, data
, length
);
177 buf
->offset
+= length
;
178 local_irq_restore(flags
);
182 * __relay_write - write data into the channel
183 * @chan: relay channel
184 * @data: data to be written
185 * @length: number of bytes to write
187 * Writes data into the current cpu's channel buffer.
189 * Protects the buffer by disabling preemption. Use
190 * relay_write() if you might be logging from interrupt
193 static inline void __relay_write(struct rchan
*chan
,
197 struct rchan_buf
*buf
;
199 buf
= chan
->buf
[get_cpu()];
200 if (unlikely(buf
->offset
+ length
> buf
->chan
->subbuf_size
))
201 length
= relay_switch_subbuf(buf
, length
);
202 memcpy(buf
->data
+ buf
->offset
, data
, length
);
203 buf
->offset
+= length
;
208 * relay_reserve - reserve slot in channel buffer
209 * @chan: relay channel
210 * @length: number of bytes to reserve
212 * Returns pointer to reserved slot, NULL if full.
214 * Reserves a slot in the current cpu's channel buffer.
215 * Does not protect the buffer at all - caller must provide
216 * appropriate synchronization.
218 static inline void *relay_reserve(struct rchan
*chan
, size_t length
)
221 struct rchan_buf
*buf
= chan
->buf
[smp_processor_id()];
223 if (unlikely(buf
->offset
+ length
> buf
->chan
->subbuf_size
)) {
224 length
= relay_switch_subbuf(buf
, length
);
228 reserved
= buf
->data
+ buf
->offset
;
229 buf
->offset
+= length
;
235 * subbuf_start_reserve - reserve bytes at the start of a sub-buffer
236 * @buf: relay channel buffer
237 * @length: number of bytes to reserve
239 * Helper function used to reserve bytes at the beginning of
240 * a sub-buffer in the subbuf_start() callback.
242 static inline void subbuf_start_reserve(struct rchan_buf
*buf
,
245 BUG_ON(length
>= buf
->chan
->subbuf_size
- 1);
246 buf
->offset
= length
;
250 * exported relayfs file operations, fs/relayfs/inode.c
253 extern struct file_operations relayfs_file_operations
;
255 #endif /* _LINUX_RELAYFS_FS_H */