[net-next-2.6.git] / include / linux / relay.h

/*
 * linux/include/linux/relay.h
 *
 * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
 * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
 *
 * CONFIG_RELAY definitions and declarations
 */

#ifndef _LINUX_RELAY_H
#define _LINUX_RELAY_H

#include <linux/config.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/kref.h>

/* Needs a _much_ better name... */
#define FIX_SIZE(x) ((((x) - 1) & PAGE_MASK) + PAGE_SIZE)

/*
 * Tracks changes to rchan/rchan_buf structs
 */
#define RELAYFS_CHANNEL_VERSION		6

/*
 * Per-cpu relay channel buffer
 */
struct rchan_buf
{
	void *start;			/* start of channel buffer */
	void *data;			/* start of current sub-buffer */
	size_t offset;			/* current offset into sub-buffer */
	size_t subbufs_produced;	/* count of sub-buffers produced */
	size_t subbufs_consumed;	/* count of sub-buffers consumed */
	struct rchan *chan;		/* associated channel */
	wait_queue_head_t read_wait;	/* reader wait queue */
	struct work_struct wake_readers; /* reader wake-up work struct */
	struct dentry *dentry;		/* channel file dentry */
	struct kref kref;		/* channel buffer refcount */
	struct page **page_array;	/* array of current buffer pages */
	unsigned int page_count;	/* number of current buffer pages */
	unsigned int finalized;		/* buffer has been finalized */
	size_t *padding;		/* padding counts per sub-buffer */
	size_t prev_padding;		/* temporary variable */
	size_t bytes_consumed;		/* bytes consumed in cur read subbuf */
	unsigned int cpu;		/* this buf's cpu */
} ____cacheline_aligned;

/*
 * Relay channel data structure
 */
struct rchan
{
	u32 version;			/* the version of this struct */
	size_t subbuf_size;		/* sub-buffer size */
	size_t n_subbufs;		/* number of sub-buffers per buffer */
	size_t alloc_size;		/* total buffer size allocated */
	struct rchan_callbacks *cb;	/* client callbacks */
	struct kref kref;		/* channel refcount */
	void *private_data;		/* for user-defined data */
	size_t last_toobig;		/* tried to log event > subbuf size */
	struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */
};

/*
 * Relay channel client callbacks
 */
struct rchan_callbacks
{
	/*
	 * subbuf_start - called on buffer-switch to a new sub-buffer
	 * @buf: the channel buffer containing the new sub-buffer
	 * @subbuf: the start of the new sub-buffer
	 * @prev_subbuf: the start of the previous sub-buffer
	 * @prev_padding: unused space at the end of previous sub-buffer
	 *
	 * The client should return 1 to continue logging, 0 to stop
	 * logging.
	 *
	 * NOTE: subbuf_start will also be invoked when the buffer is
	 *       created, so that the first sub-buffer can be initialized
	 *       if necessary.  In this case, prev_subbuf will be NULL.
	 *
	 * NOTE: the client can reserve bytes at the beginning of the new
	 *       sub-buffer by calling subbuf_start_reserve() in this callback.
	 */
	int (*subbuf_start) (struct rchan_buf *buf,
			     void *subbuf,
			     void *prev_subbuf,
			     size_t prev_padding);

	/*
	 * buf_mapped - relay buffer mmap notification
	 * @buf: the channel buffer
	 * @filp: relay file pointer
	 *
	 * Called when a relay file is successfully mmapped
	 */
        void (*buf_mapped)(struct rchan_buf *buf,
			   struct file *filp);

	/*
	 * buf_unmapped - relay buffer unmap notification
	 * @buf: the channel buffer
	 * @filp: relay file pointer
	 *
	 * Called when a relay file is successfully unmapped
	 */
        void (*buf_unmapped)(struct rchan_buf *buf,
			     struct file *filp);
	/*
	 * create_buf_file - create file to represent a relay channel buffer
	 * @filename: the name of the file to create
	 * @parent: the parent of the file to create
	 * @mode: the mode of the file to create
	 * @buf: the channel buffer
	 * @is_global: outparam - set non-zero if the buffer should be global
	 *
	 * Called during relay_open(), once for each per-cpu buffer,
	 * to allow the client to create a file to be used to
	 * represent the corresponding channel buffer.  If the file is
	 * created outside of relay, the parent must also exist in
	 * that filesystem.
	 *
	 * The callback should return the dentry of the file created
	 * to represent the relay buffer.
	 *
	 * Setting the is_global outparam to a non-zero value will
	 * cause relay_open() to create a single global buffer rather
	 * than the default set of per-cpu buffers.
	 *
	 * See Documentation/filesystems/relayfs.txt for more info.
	 */
	struct dentry *(*create_buf_file)(const char *filename,
					  struct dentry *parent,
					  int mode,
					  struct rchan_buf *buf,
					  int *is_global);

	/*
	 * remove_buf_file - remove file representing a relay channel buffer
	 * @dentry: the dentry of the file to remove
	 *
	 * Called during relay_close(), once for each per-cpu buffer,
	 * to allow the client to remove a file used to represent a
	 * channel buffer.
	 *
	 * The callback should return 0 if successful, negative if not.
	 */
	int (*remove_buf_file)(struct dentry *dentry);
};

/*
 * CONFIG_RELAY kernel API, kernel/relay.c
 */

struct rchan *relay_open(const char *base_filename,
			 struct dentry *parent,
			 size_t subbuf_size,
			 size_t n_subbufs,
			 struct rchan_callbacks *cb);
extern void relay_close(struct rchan *chan);
extern void relay_flush(struct rchan *chan);
extern void relay_subbufs_consumed(struct rchan *chan,
				   unsigned int cpu,
				   size_t consumed);
extern void relay_reset(struct rchan *chan);
extern int relay_buf_full(struct rchan_buf *buf);

extern size_t relay_switch_subbuf(struct rchan_buf *buf,
				  size_t length);

/**
 *	relay_write - write data into the channel
 *	@chan: relay channel
 *	@data: data to be written
 *	@length: number of bytes to write
 *
 *	Writes data into the current cpu's channel buffer.
 *
 *	Protects the buffer by disabling interrupts.  Use this
 *	if you might be logging from interrupt context.  Try
 *	__relay_write() if you know you	won't be logging from
 *	interrupt context.
 */
static inline void relay_write(struct rchan *chan,
			       const void *data,
			       size_t length)
{
	unsigned long flags;
	struct rchan_buf *buf;

	local_irq_save(flags);
	buf = chan->buf[smp_processor_id()];
	if (unlikely(buf->offset + length > chan->subbuf_size))
		length = relay_switch_subbuf(buf, length);
	memcpy(buf->data + buf->offset, data, length);
	buf->offset += length;
	local_irq_restore(flags);
}

/**
 *	__relay_write - write data into the channel
 *	@chan: relay channel
 *	@data: data to be written
 *	@length: number of bytes to write
 *
 *	Writes data into the current cpu's channel buffer.
 *
 *	Protects the buffer by disabling preemption.  Use
 *	relay_write() if you might be logging from interrupt
 *	context.
 */
static inline void __relay_write(struct rchan *chan,
				 const void *data,
				 size_t length)
{
	struct rchan_buf *buf;

	buf = chan->buf[get_cpu()];
	if (unlikely(buf->offset + length > buf->chan->subbuf_size))
		length = relay_switch_subbuf(buf, length);
	memcpy(buf->data + buf->offset, data, length);
	buf->offset += length;
	put_cpu();
}

/**
 *	relay_reserve - reserve slot in channel buffer
 *	@chan: relay channel
 *	@length: number of bytes to reserve
 *
 *	Returns pointer to reserved slot, NULL if full.
 *
 *	Reserves a slot in the current cpu's channel buffer.
 *	Does not protect the buffer at all - caller must provide
 *	appropriate synchronization.
 */
static inline void *relay_reserve(struct rchan *chan, size_t length)
{
	void *reserved;
	struct rchan_buf *buf = chan->buf[smp_processor_id()];

	if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
		length = relay_switch_subbuf(buf, length);
		if (!length)
			return NULL;
	}
	reserved = buf->data + buf->offset;
	buf->offset += length;

	return reserved;
}

/**
 *	subbuf_start_reserve - reserve bytes at the start of a sub-buffer
 *	@buf: relay channel buffer
 *	@length: number of bytes to reserve
 *
 *	Helper function used to reserve bytes at the beginning of
 *	a sub-buffer in the subbuf_start() callback.
 */
static inline void subbuf_start_reserve(struct rchan_buf *buf,
					size_t length)
{
	BUG_ON(length >= buf->chan->subbuf_size - 1);
	buf->offset = length;
}

/*
 * exported relay file operations, kernel/relay.c
 */
extern struct file_operations relay_file_operations;

#endif /* _LINUX_RELAY_H */
Commit	Line	Data
b86ff981 JA	1	/*
	2	* linux/include/linux/relay.h
	3	*
	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)
	6	*
	7	* CONFIG_RELAY definitions and declarations
	8	*/
	9
	10	#ifndef _LINUX_RELAY_H
	11	#define _LINUX_RELAY_H
	12
	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>
	18	#include <linux/fs.h>
	19	#include <linux/poll.h>
	20	#include <linux/kref.h>
	21
	22	/* Needs a _much_ better name... */
	23	#define FIX_SIZE(x) ((((x) - 1) & PAGE_MASK) + PAGE_SIZE)
	24
	25	/*
	26	* Tracks changes to rchan/rchan_buf structs
	27	*/
	28	#define RELAYFS_CHANNEL_VERSION 6
	29
	30	/*
	31	* Per-cpu relay channel buffer
	32	*/
	33	struct rchan_buf
	34	{
	35	void start; / start of channel buffer */
	36	void data; / start of current sub-buffer */
	37	size_t offset; /* current offset into sub-buffer */
	38	size_t subbufs_produced; /* count of sub-buffers produced */
	39	size_t subbufs_consumed; /* count of sub-buffers consumed */
	40	struct rchan chan; / associated channel */
	41	wait_queue_head_t read_wait; /* reader wait queue */
	42	struct work_struct wake_readers; /* reader wake-up work struct */
	43	struct dentry dentry; / channel file dentry */
	44	struct kref kref; /* channel buffer refcount */
	45	struct page *page_array; / array of current buffer pages */
	46	unsigned int page_count; /* number of current buffer pages */
	47	unsigned int finalized; /* buffer has been finalized */
	48	size_t padding; / padding counts per sub-buffer */
	49	size_t prev_padding; /* temporary variable */
	50	size_t bytes_consumed; /* bytes consumed in cur read subbuf */
	51	unsigned int cpu; /* this buf's cpu */
	52	} ____cacheline_aligned;
	53
	54	/*
	55	* Relay channel data structure
	56	*/
	57	struct rchan
	58	{
	59	u32 version; /* the version of this struct */
	60	size_t subbuf_size; /* sub-buffer size */
	61	size_t n_subbufs; /* number of sub-buffers per buffer */
	62	size_t alloc_size; /* total buffer size allocated */
	63	struct rchan_callbacks cb; / client callbacks */
	64	struct kref kref; /* channel refcount */
65	void private_data; / for user-defined data */
66	size_t last_toobig; /* tried to log event > subbuf size */
67	struct rchan_buf buf[NR_CPUS]; / per-cpu channel buffers */
68	};
69
70	/*
71	* Relay channel client callbacks
72	*/
73	struct rchan_callbacks
74	{
75	/*
76	* subbuf_start - called on buffer-switch to a new sub-buffer
77	* @buf: the channel buffer containing the new sub-buffer
78	* @subbuf: the start of the new sub-buffer
79	* @prev_subbuf: the start of the previous sub-buffer
80	* @prev_padding: unused space at the end of previous sub-buffer
81	*
82	* The client should return 1 to continue logging, 0 to stop
83	* logging.
84	*
85	* NOTE: subbuf_start will also be invoked when the buffer is
86	* created, so that the first sub-buffer can be initialized
87	* if necessary. In this case, prev_subbuf will be NULL.
88	*
89	* NOTE: the client can reserve bytes at the beginning of the new
90	* sub-buffer by calling subbuf_start_reserve() in this callback.
91	*/
92	int (subbuf_start) (struct rchan_buf buf,
93	void *subbuf,
94	void *prev_subbuf,
95	size_t prev_padding);
96
97	/*
98	* buf_mapped - relay buffer mmap notification
99	* @buf: the channel buffer
100	* @filp: relay file pointer
101	*
102	* Called when a relay file is successfully mmapped
103	*/
104	void (buf_mapped)(struct rchan_buf buf,
105	struct file *filp);
106
107	/*
108	* buf_unmapped - relay buffer unmap notification
109	* @buf: the channel buffer
110	* @filp: relay file pointer
111	*
112	* Called when a relay file is successfully unmapped
113	*/
114	void (buf_unmapped)(struct rchan_buf buf,
115	struct file *filp);
116	/*
117	* create_buf_file - create file to represent a relay channel buffer
118	* @filename: the name of the file to create
119	* @parent: the parent of the file to create
120	* @mode: the mode of the file to create
121	* @buf: the channel buffer
122	* @is_global: outparam - set non-zero if the buffer should be global
123	*
124	* Called during relay_open(), once for each per-cpu buffer,
125	* to allow the client to create a file to be used to
126	* represent the corresponding channel buffer. If the file is
127	* created outside of relay, the parent must also exist in
128	* that filesystem.
129	*
130	* The callback should return the dentry of the file created
131	* to represent the relay buffer.
132	*
133	* Setting the is_global outparam to a non-zero value will
134	* cause relay_open() to create a single global buffer rather
135	* than the default set of per-cpu buffers.
136	*
137	* See Documentation/filesystems/relayfs.txt for more info.
138	*/
139	struct dentry (create_buf_file)(const char *filename,
140	struct dentry *parent,
141	int mode,
142	struct rchan_buf *buf,
143	int *is_global);
144
145	/*
146	* remove_buf_file - remove file representing a relay channel buffer
147	* @dentry: the dentry of the file to remove
148	*
149	* Called during relay_close(), once for each per-cpu buffer,
150	* to allow the client to remove a file used to represent a
151	* channel buffer.
152	*
153	* The callback should return 0 if successful, negative if not.
154	*/
155	int (remove_buf_file)(struct dentry dentry);
156	};
157
158	/*
159	* CONFIG_RELAY kernel API, kernel/relay.c
160	*/
161
162	struct rchan relay_open(const char base_filename,
163	struct dentry *parent,
164	size_t subbuf_size,
165	size_t n_subbufs,
166	struct rchan_callbacks *cb);
167	extern void relay_close(struct rchan *chan);
168	extern void relay_flush(struct rchan *chan);
169	extern void relay_subbufs_consumed(struct rchan *chan,
170	unsigned int cpu,
171	size_t consumed);
172	extern void relay_reset(struct rchan *chan);
173	extern int relay_buf_full(struct rchan_buf *buf);
174
175	extern size_t relay_switch_subbuf(struct rchan_buf *buf,
176	size_t length);
177
178	/**
179	* relay_write - write data into the channel
180	* @chan: relay channel
181	* @data: data to be written
182	* @length: number of bytes to write
183	*
184	* Writes data into the current cpu's channel buffer.
185	*
186	* Protects the buffer by disabling interrupts. Use this
187	* if you might be logging from interrupt context. Try
188	* __relay_write() if you know you won't be logging from
189	* interrupt context.
190	*/
191	static inline void relay_write(struct rchan *chan,
192	const void *data,
193	size_t length)
194	{
195	unsigned long flags;
196	struct rchan_buf *buf;
197
198	local_irq_save(flags);
199	buf = chan->buf[smp_processor_id()];
200	if (unlikely(buf->offset + length > chan->subbuf_size))
201	length = relay_switch_subbuf(buf, length);
202	memcpy(buf->data + buf->offset, data, length);
203	buf->offset += length;
204	local_irq_restore(flags);
205	}
206
207	/**
208	* __relay_write - write data into the channel
209	* @chan: relay channel
210	* @data: data to be written
211	* @length: number of bytes to write
212	*
213	* Writes data into the current cpu's channel buffer.
214	*
215	* Protects the buffer by disabling preemption. Use
216	* relay_write() if you might be logging from interrupt
217	* context.
218	*/
219	static inline void __relay_write(struct rchan *chan,
220	const void *data,
221	size_t length)
222	{
223	struct rchan_buf *buf;
224
225	buf = chan->buf[get_cpu()];
226	if (unlikely(buf->offset + length > buf->chan->subbuf_size))
227	length = relay_switch_subbuf(buf, length);
228	memcpy(buf->data + buf->offset, data, length);
229	buf->offset += length;
230	put_cpu();
231	}
232
233	/**
234	* relay_reserve - reserve slot in channel buffer
235	* @chan: relay channel
236	* @length: number of bytes to reserve
237	*
238	* Returns pointer to reserved slot, NULL if full.
239	*
240	* Reserves a slot in the current cpu's channel buffer.
241	* Does not protect the buffer at all - caller must provide
242	* appropriate synchronization.
243	*/
244	static inline void relay_reserve(struct rchan chan, size_t length)
245	{
246	void *reserved;
247	struct rchan_buf *buf = chan->buf[smp_processor_id()];
248
249	if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
250	length = relay_switch_subbuf(buf, length);
251	if (!length)
252	return NULL;
253	}
254	reserved = buf->data + buf->offset;
255	buf->offset += length;
256
257	return reserved;
258	}
259
260	/**
261	* subbuf_start_reserve - reserve bytes at the start of a sub-buffer
262	* @buf: relay channel buffer
263	* @length: number of bytes to reserve
264	*
265	* Helper function used to reserve bytes at the beginning of
266	* a sub-buffer in the subbuf_start() callback.
267	*/
268	static inline void subbuf_start_reserve(struct rchan_buf *buf,
269	size_t length)
270	{
271	BUG_ON(length >= buf->chan->subbuf_size - 1);
272	buf->offset = length;
273	}
274
275	/*
276	* exported relay file operations, kernel/relay.c
277	*/
278	extern struct file_operations relay_file_operations;
279
280	#endif /* _LINUX_RELAY_H */
281