trace_seq.c (8dd06ef34b6e2f41b29fbf5fc1663780f2524285) trace_seq.c (f2cc020d7876de7583feb52ec939a32419cf9468)
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * trace_seq.c
4 *
5 * Copyright (C) 2008-2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
6 *
7 * The trace_seq is a handy tool that allows you to pass a descriptor around
8 * to a buffer that other functions can write to. It is similar to the
9 * seq_file functionality but has some differences.
10 *
11 * To use it, the trace_seq must be initialized with trace_seq_init().
12 * This will set up the counters within the descriptor. You can call
13 * trace_seq_init() more than once to reset the trace_seq to start
14 * from scratch.
15 *
16 * The buffer size is currently PAGE_SIZE, although it may become dynamic
17 * in the future.
18 *
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * trace_seq.c
4 *
5 * Copyright (C) 2008-2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
6 *
7 * The trace_seq is a handy tool that allows you to pass a descriptor around
8 * to a buffer that other functions can write to. It is similar to the
9 * seq_file functionality but has some differences.
10 *
11 * To use it, the trace_seq must be initialized with trace_seq_init().
12 * This will set up the counters within the descriptor. You can call
13 * trace_seq_init() more than once to reset the trace_seq to start
14 * from scratch.
15 *
16 * The buffer size is currently PAGE_SIZE, although it may become dynamic
17 * in the future.
18 *
19 * A write to the buffer will either succed or fail. That is, unlike
19 * A write to the buffer will either succeed or fail. That is, unlike
20 * sprintf() there will not be a partial write (well it may write into
21 * the buffer but it wont update the pointers). This allows users to
22 * try to write something into the trace_seq buffer and if it fails
23 * they can flush it and try again.
24 *
25 */
26#include <linux/uaccess.h>
27#include <linux/seq_file.h>

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68}
69
70/**
71 * trace_seq_printf - sequence printing of trace information
72 * @s: trace sequence descriptor
73 * @fmt: printf format string
74 *
75 * The tracer may use either sequence operations or its own
20 * sprintf() there will not be a partial write (well it may write into
21 * the buffer but it wont update the pointers). This allows users to
22 * try to write something into the trace_seq buffer and if it fails
23 * they can flush it and try again.
24 *
25 */
26#include <linux/uaccess.h>
27#include <linux/seq_file.h>

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68}
69
70/**
71 * trace_seq_printf - sequence printing of trace information
72 * @s: trace sequence descriptor
73 * @fmt: printf format string
74 *
75 * The tracer may use either sequence operations or its own
76 * copy to user routines. To simplify formating of a trace
76 * copy to user routines. To simplify formatting of a trace
77 * trace_seq_printf() is used to store strings into a special
78 * buffer (@s). Then the output may be either used by
79 * the sequencer or pulled into another buffer.
80 */
81void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
82{
83 unsigned int save_len = s->seq.len;
84 va_list ap;

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128EXPORT_SYMBOL_GPL(trace_seq_bitmask);
129
130/**
131 * trace_seq_vprintf - sequence printing of trace information
132 * @s: trace sequence descriptor
133 * @fmt: printf format string
134 *
135 * The tracer may use either sequence operations or its own
77 * trace_seq_printf() is used to store strings into a special
78 * buffer (@s). Then the output may be either used by
79 * the sequencer or pulled into another buffer.
80 */
81void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
82{
83 unsigned int save_len = s->seq.len;
84 va_list ap;

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128EXPORT_SYMBOL_GPL(trace_seq_bitmask);
129
130/**
131 * trace_seq_vprintf - sequence printing of trace information
132 * @s: trace sequence descriptor
133 * @fmt: printf format string
134 *
135 * The tracer may use either sequence operations or its own
136 * copy to user routines. To simplify formating of a trace
136 * copy to user routines. To simplify formatting of a trace
137 * trace_seq_printf is used to store strings into a special
138 * buffer (@s). Then the output may be either used by
139 * the sequencer or pulled into another buffer.
140 */
141void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
142{
143 unsigned int save_len = s->seq.len;
144

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221EXPORT_SYMBOL_GPL(trace_seq_puts);
222
223/**
224 * trace_seq_putc - trace sequence printing of simple character
225 * @s: trace sequence descriptor
226 * @c: simple character to record
227 *
228 * The tracer may use either the sequence operations or its own
137 * trace_seq_printf is used to store strings into a special
138 * buffer (@s). Then the output may be either used by
139 * the sequencer or pulled into another buffer.
140 */
141void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
142{
143 unsigned int save_len = s->seq.len;
144

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221EXPORT_SYMBOL_GPL(trace_seq_puts);
222
223/**
224 * trace_seq_putc - trace sequence printing of simple character
225 * @s: trace sequence descriptor
226 * @c: simple character to record
227 *
228 * The tracer may use either the sequence operations or its own
229 * copy to user routines. This function records a simple charater
229 * copy to user routines. This function records a simple character
230 * into a special buffer (@s) for later retrieval by a sequencer
231 * or other mechanism.
232 */
233void trace_seq_putc(struct trace_seq *s, unsigned char c)
234{
235 if (s->full)
236 return;
237

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343 return 0;
344 }
345
346 return 1;
347}
348EXPORT_SYMBOL_GPL(trace_seq_path);
349
350/**
230 * into a special buffer (@s) for later retrieval by a sequencer
231 * or other mechanism.
232 */
233void trace_seq_putc(struct trace_seq *s, unsigned char c)
234{
235 if (s->full)
236 return;
237

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343 return 0;
344 }
345
346 return 1;
347}
348EXPORT_SYMBOL_GPL(trace_seq_path);
349
350/**
351 * trace_seq_to_user - copy the squence buffer to user space
351 * trace_seq_to_user - copy the sequence buffer to user space
352 * @s: trace sequence descriptor
353 * @ubuf: The userspace memory location to copy to
354 * @cnt: The amount to copy
355 *
356 * Copies the sequence buffer into the userspace memory pointed to
357 * by @ubuf. It starts from the last read position (@s->readpos)
358 * and writes up to @cnt characters or till it reaches the end of
359 * the content in the buffer (@s->len), which ever comes first.
360 *
361 * On success, it returns a positive number of the number of bytes
362 * it copied.
363 *
364 * On failure it returns -EBUSY if all of the content in the
365 * sequence has been already read, which includes nothing in the
352 * @s: trace sequence descriptor
353 * @ubuf: The userspace memory location to copy to
354 * @cnt: The amount to copy
355 *
356 * Copies the sequence buffer into the userspace memory pointed to
357 * by @ubuf. It starts from the last read position (@s->readpos)
358 * and writes up to @cnt characters or till it reaches the end of
359 * the content in the buffer (@s->len), which ever comes first.
360 *
361 * On success, it returns a positive number of the number of bytes
362 * it copied.
363 *
364 * On failure it returns -EBUSY if all of the content in the
365 * sequence has been already read, which includes nothing in the
366 * sequenc (@s->len == @s->readpos).
366 * sequence (@s->len == @s->readpos).
367 *
368 * Returns -EFAULT if the copy to userspace fails.
369 */
370int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
371{
372 __trace_seq_init(s);
373 return seq_buf_to_user(&s->seq, ubuf, cnt);
374}

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368 * Returns -EFAULT if the copy to userspace fails.
369 */
370int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
371{
372 __trace_seq_init(s);
373 return seq_buf_to_user(&s->seq, ubuf, cnt);
374}

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