[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/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 delayed_work 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
b86ff981 JA	13	#include <linux/types.h>
	14	#include <linux/sched.h>
	15	#include <linux/wait.h>
	16	#include <linux/list.h>
	17	#include <linux/fs.h>
	18	#include <linux/poll.h>
	19	#include <linux/kref.h>
	20
	21	/* Needs a _much_ better name... */
	22	#define FIX_SIZE(x) ((((x) - 1) & PAGE_MASK) + PAGE_SIZE)
	23
	24	/*
	25	* Tracks changes to rchan/rchan_buf structs
	26	*/
	27	#define RELAYFS_CHANNEL_VERSION 6
	28
	29	/*
	30	* Per-cpu relay channel buffer
	31	*/
	32	struct rchan_buf
	33	{
	34	void start; / start of channel buffer */
	35	void data; / start of current sub-buffer */
	36	size_t offset; /* current offset into sub-buffer */
	37	size_t subbufs_produced; /* count of sub-buffers produced */
	38	size_t subbufs_consumed; /* count of sub-buffers consumed */
	39	struct rchan chan; / associated channel */
	40	wait_queue_head_t read_wait; /* reader wait queue */
c4028958	41	struct delayed_work wake_readers; /* reader wake-up work struct */
b86ff981 JA	42	struct dentry dentry; / channel file dentry */
	43	struct kref kref; /* channel buffer refcount */
	44	struct page *page_array; / array of current buffer pages */
	45	unsigned int page_count; /* number of current buffer pages */
	46	unsigned int finalized; /* buffer has been finalized */
	47	size_t padding; / padding counts per sub-buffer */
	48	size_t prev_padding; /* temporary variable */
	49	size_t bytes_consumed; /* bytes consumed in cur read subbuf */
	50	unsigned int cpu; /* this buf's cpu */
	51	} ____cacheline_aligned;
	52
	53	/*
	54	* Relay channel data structure
	55	*/
	56	struct rchan
	57	{
	58	u32 version; /* the version of this struct */
	59	size_t subbuf_size; /* sub-buffer size */
	60	size_t n_subbufs; /* number of sub-buffers per buffer */
	61	size_t alloc_size; /* total buffer size allocated */
	62	struct rchan_callbacks cb; / client callbacks */
	63	struct kref kref; /* channel refcount */
	64	void private_data; / for user-defined data */
	65	size_t last_toobig; /* tried to log event > subbuf size */
	66	struct rchan_buf buf[NR_CPUS]; / per-cpu channel buffers */
	67	};
	68
	69	/*
	70	* Relay channel client callbacks
	71	*/
	72	struct rchan_callbacks
	73	{
	74	/*
	75	* subbuf_start - called on buffer-switch to a new sub-buffer
	76	* @buf: the channel buffer containing the new sub-buffer
	77	* @subbuf: the start of the new sub-buffer
	78	* @prev_subbuf: the start of the previous sub-buffer
	79	* @prev_padding: unused space at the end of previous sub-buffer
	80	*
	81	* The client should return 1 to continue logging, 0 to stop
	82	* logging.
	83	*
	84	* NOTE: subbuf_start will also be invoked when the buffer is
	85	* created, so that the first sub-buffer can be initialized
	86	* if necessary. In this case, prev_subbuf will be NULL.
	87	*
	88	* NOTE: the client can reserve bytes at the beginning of the new
	89	* sub-buffer by calling subbuf_start_reserve() in this callback.
	90	*/
	91	int (subbuf_start) (struct rchan_buf buf,
	92	void *subbuf,
	93	void *prev_subbuf,
	94	size_t prev_padding);
	95
	96	/*
	97	* buf_mapped - relay buffer mmap notification
	98	* @buf: the channel buffer
	99	* @filp: relay file pointer
	100	*
	101	* Called when a relay file is successfully mmapped
	102	*/
	103	void (buf_mapped)(struct rchan_buf buf,
	104	struct file *filp);
	105
106	/*
107	* buf_unmapped - relay buffer unmap notification
108	* @buf: the channel buffer
109	* @filp: relay file pointer
110	*
111	* Called when a relay file is successfully unmapped
112	*/
113	void (buf_unmapped)(struct rchan_buf buf,
114	struct file *filp);
115	/*
116	* create_buf_file - create file to represent a relay channel buffer
117	* @filename: the name of the file to create
118	* @parent: the parent of the file to create
119	* @mode: the mode of the file to create
120	* @buf: the channel buffer
121	* @is_global: outparam - set non-zero if the buffer should be global
122	*
123	* Called during relay_open(), once for each per-cpu buffer,
124	* to allow the client to create a file to be used to
125	* represent the corresponding channel buffer. If the file is
126	* created outside of relay, the parent must also exist in
127	* that filesystem.
128	*
129	* The callback should return the dentry of the file created
130	* to represent the relay buffer.
131	*
132	* Setting the is_global outparam to a non-zero value will
133	* cause relay_open() to create a single global buffer rather
134	* than the default set of per-cpu buffers.
135	*
136	* See Documentation/filesystems/relayfs.txt for more info.
137	*/
138	struct dentry (create_buf_file)(const char *filename,
139	struct dentry *parent,
140	int mode,
141	struct rchan_buf *buf,
142	int *is_global);
143
144	/*
145	* remove_buf_file - remove file representing a relay channel buffer
146	* @dentry: the dentry of the file to remove
147	*
148	* Called during relay_close(), once for each per-cpu buffer,
149	* to allow the client to remove a file used to represent a
150	* channel buffer.
151	*
152	* The callback should return 0 if successful, negative if not.
153	*/
154	int (remove_buf_file)(struct dentry dentry);
155	};
156
157	/*
158	* CONFIG_RELAY kernel API, kernel/relay.c
159	*/
160
161	struct rchan relay_open(const char base_filename,
162	struct dentry *parent,
163	size_t subbuf_size,
164	size_t n_subbufs,
165	struct rchan_callbacks *cb);
166	extern void relay_close(struct rchan *chan);
167	extern void relay_flush(struct rchan *chan);
168	extern void relay_subbufs_consumed(struct rchan *chan,
169	unsigned int cpu,
170	size_t consumed);
171	extern void relay_reset(struct rchan *chan);
172	extern int relay_buf_full(struct rchan_buf *buf);
173
174	extern size_t relay_switch_subbuf(struct rchan_buf *buf,
175	size_t length);
176
177	/**
178	* relay_write - write data into the channel
179	* @chan: relay channel
180	* @data: data to be written
181	* @length: number of bytes to write
182	*
183	* Writes data into the current cpu's channel buffer.
184	*
185	* Protects the buffer by disabling interrupts. Use this
186	* if you might be logging from interrupt context. Try
187	* __relay_write() if you know you won't be logging from
188	* interrupt context.
189	*/
190	static inline void relay_write(struct rchan *chan,
191	const void *data,
192	size_t length)
193	{
194	unsigned long flags;
195	struct rchan_buf *buf;
196
197	local_irq_save(flags);
198	buf = chan->buf[smp_processor_id()];
199	if (unlikely(buf->offset + length > chan->subbuf_size))
200	length = relay_switch_subbuf(buf, length);
201	memcpy(buf->data + buf->offset, data, length);
202	buf->offset += length;
203	local_irq_restore(flags);
204	}
205
206	/**
207	* __relay_write - write data into the channel
208	* @chan: relay channel
209	* @data: data to be written
210	* @length: number of bytes to write
211	*
212	* Writes data into the current cpu's channel buffer.
213	*
214	* Protects the buffer by disabling preemption. Use
215	* relay_write() if you might be logging from interrupt
216	* context.
217	*/
218	static inline void __relay_write(struct rchan *chan,
219	const void *data,
220	size_t length)
221	{
222	struct rchan_buf *buf;
223
224	buf = chan->buf[get_cpu()];
225	if (unlikely(buf->offset + length > buf->chan->subbuf_size))
226	length = relay_switch_subbuf(buf, length);
227	memcpy(buf->data + buf->offset, data, length);
228	buf->offset += length;
229	put_cpu();
230	}
231
232	/**
233	* relay_reserve - reserve slot in channel buffer
234	* @chan: relay channel
235	* @length: number of bytes to reserve
236	*
237	* Returns pointer to reserved slot, NULL if full.
238	*
239	* Reserves a slot in the current cpu's channel buffer.
240	* Does not protect the buffer at all - caller must provide
241	* appropriate synchronization.
242	*/
243	static inline void relay_reserve(struct rchan chan, size_t length)
244	{
245	void *reserved;
246	struct rchan_buf *buf = chan->buf[smp_processor_id()];
247
248	if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
249	length = relay_switch_subbuf(buf, length);
250	if (!length)
251	return NULL;
252	}
253	reserved = buf->data + buf->offset;
254	buf->offset += length;
255
256	return reserved;
257	}
258
259	/**
260	* subbuf_start_reserve - reserve bytes at the start of a sub-buffer
261	* @buf: relay channel buffer
262	* @length: number of bytes to reserve
263	*
264	* Helper function used to reserve bytes at the beginning of
265	* a sub-buffer in the subbuf_start() callback.
266	*/
267	static inline void subbuf_start_reserve(struct rchan_buf *buf,
268	size_t length)
269	{
270	BUG_ON(length >= buf->chan->subbuf_size - 1);
271	buf->offset = length;
272	}
273
274	/*
275	* exported relay file operations, kernel/relay.c
276	*/
277	extern struct file_operations relay_file_operations;
278
279	#endif /* _LINUX_RELAY_H */
280