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tracing: create generic trace parser
Create a "trace_parser" that can parse the user space input for separate words. struct trace_parser is the descriptor. Generic "trace_get_user" function that can be a helper to read multiple words passed in by user space. Signed-off-by: Jiri Olsa <jolsa@redhat.com> LKML-Reference: <1252682969-3366-2-git-send-email-jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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@ -339,6 +339,112 @@ static struct {
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int trace_clock_id;
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/*
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* trace_parser_get_init - gets the buffer for trace parser
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*/
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int trace_parser_get_init(struct trace_parser *parser, int size)
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{
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memset(parser, 0, sizeof(*parser));
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parser->buffer = kmalloc(size, GFP_KERNEL);
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if (!parser->buffer)
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return 1;
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parser->size = size;
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return 0;
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}
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/*
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* trace_parser_put - frees the buffer for trace parser
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*/
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void trace_parser_put(struct trace_parser *parser)
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{
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kfree(parser->buffer);
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}
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/*
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* trace_get_user - reads the user input string separated by space
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* (matched by isspace(ch))
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*
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* For each string found the 'struct trace_parser' is updated,
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* and the function returns.
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*
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* Returns number of bytes read.
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*
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* See kernel/trace/trace.h for 'struct trace_parser' details.
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*/
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int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
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size_t cnt, loff_t *ppos)
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{
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char ch;
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size_t read = 0;
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ssize_t ret;
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if (!*ppos)
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trace_parser_clear(parser);
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ret = get_user(ch, ubuf++);
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if (ret)
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goto out;
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read++;
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cnt--;
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/*
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* The parser is not finished with the last write,
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* continue reading the user input without skipping spaces.
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*/
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if (!parser->cont) {
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/* skip white space */
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while (cnt && isspace(ch)) {
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ret = get_user(ch, ubuf++);
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if (ret)
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goto out;
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read++;
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cnt--;
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}
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/* only spaces were written */
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if (isspace(ch)) {
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*ppos += read;
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ret = read;
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goto out;
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}
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parser->idx = 0;
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}
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/* read the non-space input */
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while (cnt && !isspace(ch)) {
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if (parser->idx < parser->size)
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parser->buffer[parser->idx++] = ch;
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else {
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ret = -EINVAL;
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goto out;
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}
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ret = get_user(ch, ubuf++);
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if (ret)
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goto out;
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read++;
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cnt--;
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}
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/* We either got finished input or we have to wait for another call. */
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if (isspace(ch)) {
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parser->buffer[parser->idx] = 0;
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parser->cont = false;
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} else {
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parser->cont = true;
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parser->buffer[parser->idx++] = ch;
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}
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*ppos += read;
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ret = read;
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out:
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return ret;
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}
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ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
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{
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int len;
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@ -615,6 +615,41 @@ static inline int ftrace_trace_task(struct task_struct *task)
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}
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#endif
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/*
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* struct trace_parser - servers for reading the user input separated by spaces
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* @cont: set if the input is not complete - no final space char was found
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* @buffer: holds the parsed user input
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* @idx: user input lenght
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* @size: buffer size
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*/
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struct trace_parser {
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bool cont;
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char *buffer;
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unsigned idx;
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unsigned size;
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};
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static inline bool trace_parser_loaded(struct trace_parser *parser)
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{
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return (parser->idx != 0);
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}
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static inline bool trace_parser_cont(struct trace_parser *parser)
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{
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return parser->cont;
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}
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static inline void trace_parser_clear(struct trace_parser *parser)
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{
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parser->cont = false;
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parser->idx = 0;
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}
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extern int trace_parser_get_init(struct trace_parser *parser, int size);
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extern void trace_parser_put(struct trace_parser *parser);
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extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
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size_t cnt, loff_t *ppos);
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/*
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* trace_iterator_flags is an enumeration that defines bit
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* positions into trace_flags that controls the output.
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