OSCL-LXR linux-6.0.1/​kernel/​trace/​trace_seq.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * trace_seq.c
  *
  * Copyright (C) 2008-2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
  *
  * The trace_seq is a handy tool that allows you to pass a descriptor around
  * to a buffer that other functions can write to. It is similar to the
  * seq_file functionality but has some differences.
  *
  * To use it, the trace_seq must be initialized with trace_seq_init().
  * This will set up the counters within the descriptor. You can call
  * trace_seq_init() more than once to reset the trace_seq to start
  * from scratch.
  * 
  * The buffer size is currently PAGE_SIZE, although it may become dynamic
  * in the future.
  *
  * A write to the buffer will either succeed or fail. That is, unlike
  * sprintf() there will not be a partial write (well it may write into
  * the buffer but it wont update the pointers). This allows users to
  * try to write something into the trace_seq buffer and if it fails
  * they can flush it and try again.
  *
  */
 #include <linux/uaccess.h>
 #include <linux/seq_file.h>
 #include <linux/trace_seq.h>
 
 /* How much buffer is left on the trace_seq? */
 #define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
 
 /*
  * trace_seq should work with being initialized with 0s.
  */
 static inline void __trace_seq_init(struct trace_seq *s)
 {
     if (unlikely(!s->seq.size))
         trace_seq_init(s);
 }
 
 /**
  * trace_print_seq - move the contents of trace_seq into a seq_file
  * @m: the seq_file descriptor that is the destination
  * @s: the trace_seq descriptor that is the source.
  *
  * Returns 0 on success and non zero on error. If it succeeds to
  * write to the seq_file it will reset the trace_seq, otherwise
  * it does not modify the trace_seq to let the caller try again.
  */
 int trace_print_seq(struct seq_file *m, struct trace_seq *s)
 {
     int ret;
 
     __trace_seq_init(s);
 
     ret = seq_buf_print_seq(m, &s->seq);
 
     /*
      * Only reset this buffer if we successfully wrote to the
      * seq_file buffer. This lets the caller try again or
      * do something else with the contents.
      */
     if (!ret)
         trace_seq_init(s);
 
     return ret;
 }
 
 /**
  * trace_seq_printf - sequence printing of trace information
  * @s: trace sequence descriptor
  * @fmt: printf format string
  *
  * The tracer may use either sequence operations or its own
  * copy to user routines. To simplify formatting of a trace
  * trace_seq_printf() is used to store strings into a special
  * buffer (@s). Then the output may be either used by
  * the sequencer or pulled into another buffer.
  */
 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 {
     unsigned int save_len = s->seq.len;
     va_list ap;
 
     if (s->full)
         return;
 
     __trace_seq_init(s);
 
     va_start(ap, fmt);
     seq_buf_vprintf(&s->seq, fmt, ap);
     va_end(ap);
 
     /* If we can't write it all, don't bother writing anything */
     if (unlikely(seq_buf_has_overflowed(&s->seq))) {
         s->seq.len = save_len;
         s->full = 1;
     }
 }
 EXPORT_SYMBOL_GPL(trace_seq_printf);
 
 /**
  * trace_seq_bitmask - write a bitmask array in its ASCII representation
  * @s:      trace sequence descriptor
  * @maskp:  points to an array of unsigned longs that represent a bitmask
  * @nmaskbits:  The number of bits that are valid in @maskp
  *
  * Writes a ASCII representation of a bitmask string into @s.
  */
 void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
               int nmaskbits)
 {
     unsigned int save_len = s->seq.len;
 
     if (s->full)
         return;
 
     __trace_seq_init(s);
 
     seq_buf_printf(&s->seq, "%*pb", nmaskbits, maskp);
 
     if (unlikely(seq_buf_has_overflowed(&s->seq))) {
         s->seq.len = save_len;
         s->full = 1;
     }
 }
 EXPORT_SYMBOL_GPL(trace_seq_bitmask);
 
 /**
  * trace_seq_vprintf - sequence printing of trace information
  * @s: trace sequence descriptor
  * @fmt: printf format string
  *
  * The tracer may use either sequence operations or its own
  * copy to user routines. To simplify formatting of a trace
  * trace_seq_printf is used to store strings into a special
  * buffer (@s). Then the output may be either used by
  * the sequencer or pulled into another buffer.
  */
 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
 {
     unsigned int save_len = s->seq.len;
 
     if (s->full)
         return;
 
     __trace_seq_init(s);
 
     seq_buf_vprintf(&s->seq, fmt, args);
 
     /* If we can't write it all, don't bother writing anything */
     if (unlikely(seq_buf_has_overflowed(&s->seq))) {
         s->seq.len = save_len;
         s->full = 1;
     }
 }
 EXPORT_SYMBOL_GPL(trace_seq_vprintf);
 
 /**
  * trace_seq_bprintf - Write the printf string from binary arguments
  * @s: trace sequence descriptor
  * @fmt: The format string for the @binary arguments
  * @binary: The binary arguments for @fmt.
  *
  * When recording in a fast path, a printf may be recorded with just
  * saving the format and the arguments as they were passed to the
  * function, instead of wasting cycles converting the arguments into
  * ASCII characters. Instead, the arguments are saved in a 32 bit
  * word array that is defined by the format string constraints.
  *
  * This function will take the format and the binary array and finish
  * the conversion into the ASCII string within the buffer.
  */
 void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 {
     unsigned int save_len = s->seq.len;
 
     if (s->full)
         return;
 
     __trace_seq_init(s);
 
     seq_buf_bprintf(&s->seq, fmt, binary);
 
     /* If we can't write it all, don't bother writing anything */
     if (unlikely(seq_buf_has_overflowed(&s->seq))) {
         s->seq.len = save_len;
         s->full = 1;
         return;
     }
 }
 EXPORT_SYMBOL_GPL(trace_seq_bprintf);
 
 /**
  * trace_seq_puts - trace sequence printing of simple string
  * @s: trace sequence descriptor
  * @str: simple string to record
  *
  * The tracer may use either the sequence operations or its own
  * copy to user routines. This function records a simple string
  * into a special buffer (@s) for later retrieval by a sequencer
  * or other mechanism.
  */
 void trace_seq_puts(struct trace_seq *s, const char *str)
 {
     unsigned int len = strlen(str);
 
     if (s->full)
         return;
 
     __trace_seq_init(s);
 
     if (len > TRACE_SEQ_BUF_LEFT(s)) {
         s->full = 1;
         return;
     }
 
     seq_buf_putmem(&s->seq, str, len);
 }
 EXPORT_SYMBOL_GPL(trace_seq_puts);
 
 /**
  * trace_seq_putc - trace sequence printing of simple character
  * @s: trace sequence descriptor
  * @c: simple character to record
  *
  * The tracer may use either the sequence operations or its own
  * copy to user routines. This function records a simple character
  * into a special buffer (@s) for later retrieval by a sequencer
  * or other mechanism.
  */
 void trace_seq_putc(struct trace_seq *s, unsigned char c)
 {
     if (s->full)
         return;
 
     __trace_seq_init(s);
 
     if (TRACE_SEQ_BUF_LEFT(s) < 1) {
         s->full = 1;
         return;
     }
 
     seq_buf_putc(&s->seq, c);
 }
 EXPORT_SYMBOL_GPL(trace_seq_putc);
 
 /**
  * trace_seq_putmem - write raw data into the trace_seq buffer
  * @s: trace sequence descriptor
  * @mem: The raw memory to copy into the buffer
  * @len: The length of the raw memory to copy (in bytes)
  *
  * There may be cases where raw memory needs to be written into the
  * buffer and a strcpy() would not work. Using this function allows
  * for such cases.
  */
 void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
 {
     if (s->full)
         return;
 
     __trace_seq_init(s);
 
     if (len > TRACE_SEQ_BUF_LEFT(s)) {
         s->full = 1;
         return;
     }
 
     seq_buf_putmem(&s->seq, mem, len);
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem);
 
 /**
  * trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex
  * @s: trace sequence descriptor
  * @mem: The raw memory to write its hex ASCII representation of
  * @len: The length of the raw memory to copy (in bytes)
  *
  * This is similar to trace_seq_putmem() except instead of just copying the
  * raw memory into the buffer it writes its ASCII representation of it
  * in hex characters.
  */
 void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
              unsigned int len)
 {
     unsigned int save_len = s->seq.len;
 
     if (s->full)
         return;
 
     __trace_seq_init(s);
 
     /* Each byte is represented by two chars */
     if (len * 2 > TRACE_SEQ_BUF_LEFT(s)) {
         s->full = 1;
         return;
     }
 
     /* The added spaces can still cause an overflow */
     seq_buf_putmem_hex(&s->seq, mem, len);
 
     if (unlikely(seq_buf_has_overflowed(&s->seq))) {
         s->seq.len = save_len;
         s->full = 1;
         return;
     }
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
 
 /**
  * trace_seq_path - copy a path into the sequence buffer
  * @s: trace sequence descriptor
  * @path: path to write into the sequence buffer.
  *
  * Write a path name into the sequence buffer.
  *
  * Returns 1 if we successfully written all the contents to
  *   the buffer.
  * Returns 0 if we the length to write is bigger than the
  *   reserved buffer space. In this case, nothing gets written.
  */
 int trace_seq_path(struct trace_seq *s, const struct path *path)
 {
     unsigned int save_len = s->seq.len;
 
     if (s->full)
         return 0;
 
     __trace_seq_init(s);
 
     if (TRACE_SEQ_BUF_LEFT(s) < 1) {
         s->full = 1;
         return 0;
     }
 
     seq_buf_path(&s->seq, path, "\n");
 
     if (unlikely(seq_buf_has_overflowed(&s->seq))) {
         s->seq.len = save_len;
         s->full = 1;
         return 0;
     }
 
     return 1;
 }
 EXPORT_SYMBOL_GPL(trace_seq_path);
 
 /**
  * trace_seq_to_user - copy the sequence buffer to user space
  * @s: trace sequence descriptor
  * @ubuf: The userspace memory location to copy to
  * @cnt: The amount to copy
  *
  * Copies the sequence buffer into the userspace memory pointed to
  * by @ubuf. It starts from the last read position (@s->readpos)
  * and writes up to @cnt characters or till it reaches the end of
  * the content in the buffer (@s->len), which ever comes first.
  *
  * On success, it returns a positive number of the number of bytes
  * it copied.
  *
  * On failure it returns -EBUSY if all of the content in the
  * sequence has been already read, which includes nothing in the
  * sequence (@s->len == @s->readpos).
  *
  * Returns -EFAULT if the copy to userspace fails.
  */
 int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
 {
     __trace_seq_init(s);
     return seq_buf_to_user(&s->seq, ubuf, cnt);
 }
 EXPORT_SYMBOL_GPL(trace_seq_to_user);
 
 int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str,
                int prefix_type, int rowsize, int groupsize,
                const void *buf, size_t len, bool ascii)
 {
     unsigned int save_len = s->seq.len;
 
     if (s->full)
         return 0;
 
     __trace_seq_init(s);
 
     if (TRACE_SEQ_BUF_LEFT(s) < 1) {
         s->full = 1;
         return 0;
     }
 
     seq_buf_hex_dump(&(s->seq), prefix_str,
            prefix_type, rowsize, groupsize,
            buf, len, ascii);
 
     if (unlikely(seq_buf_has_overflowed(&s->seq))) {
         s->seq.len = save_len;
         s->full = 1;
         return 0;
     }
 
     return 1;
 }
 EXPORT_SYMBOL(trace_seq_hex_dump);

This page was automatically generated by the 2.1.0 LXR engine. The LXR team