[tip:tracing/core] tracing: create generic trace parser

tip-bot for jolsa@redhat.com
2009-09-12T07:54:54Z

Commit-ID: b63f39ea50330f836e301ddda21c6a93dcf0d6a3
Gitweb: http://git.kernel.org/tip/b63f39ea50330f836e301ddda21c6a93dcf0d6a3
Author: jolsa@redhat.com <jolsa@redhat.com>
AuthorDate: Fri, 11 Sep 2009 17:29:27 +0200
Committer: Steven Rostedt <rostedt@goodmis.org>
CommitDate: Fri, 11 Sep 2009 14:46:55 -0400

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>

---
kernel/trace/trace.c | 106 ++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/trace/trace.h | 35 ++++++++++++++++
2 files changed, 141 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3b91828..45c3f03 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -339,6 +339,112 @@ static struct {

int trace_clock_id;

+/*
+ * trace_parser_get_init - gets the buffer for trace parser
+ */
+int trace_parser_get_init(struct trace_parser *parser, int size)
+{
+ memset(parser, 0, sizeof(*parser));
+
+ parser->buffer = kmalloc(size, GFP_KERNEL);
+ if (!parser->buffer)
+ return 1;
+
+ parser->size = size;
+ return 0;
+}
+
+/*
+ * trace_parser_put - frees the buffer for trace parser
+ */
+void trace_parser_put(struct trace_parser *parser)
+{
+ kfree(parser->buffer);
+}
+
+/*
+ * trace_get_user - reads the user input string separated by space
+ * (matched by isspace(ch))
+ *
+ * For each string found the 'struct trace_parser' is updated,
+ * and the function returns.
+ *
+ * Returns number of bytes read.
+ *
+ * See kernel/trace/trace.h for 'struct trace_parser' details.
+ */
+int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char ch;
+ size_t read = 0;
+ ssize_t ret;
+
+ if (!*ppos)
+ trace_parser_clear(parser);
+
+ ret = get_user(ch, ubuf++);
+ if (ret)
+ goto out;
+
+ read++;
+ cnt--;
+
+ /*
+ * The parser is not finished with the last write,
+ * continue reading the user input without skipping spaces.
+ */
+ if (!parser->cont) {
+ /* skip white space */
+ while (cnt && isspace(ch)) {
+ ret = get_user(ch, ubuf++);
+ if (ret)
+ goto out;
+ read++;
+ cnt--;
+ }
+
+ /* only spaces were written */
+ if (isspace(ch)) {
+ *ppos += read;
+ ret = read;
+ goto out;
+ }
+
+ parser->idx = 0;
+ }
+
+ /* read the non-space input */
+ while (cnt && !isspace(ch)) {
+ if (parser->idx < parser->size)
+ parser->buffer[parser->idx++] = ch;
+ else {
+ ret = -EINVAL;
+ goto out;
+ }
+ ret = get_user(ch, ubuf++);
+ if (ret)
+ goto out;
+ read++;
+ cnt--;
+ }
+
+ /* We either got finished input or we have to wait for another call. */
+ if (isspace(ch)) {
+ parser->buffer[parser->idx] = 0;
+ parser->cont = false;
+ } else {
+ parser->cont = true;
+ parser->buffer[parser->idx++] = ch;
+ }
+
+ *ppos += read;
+ ret = read;
+
+out:
+ return ret;
+}
+
ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
int len;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b69697b..28247ce 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -616,6 +616,41 @@ static inline int ftrace_trace_task(struct task_struct *task)
#endif

/*
+ * struct trace_parser - servers for reading the user input separated by spaces
+ * @cont: set if the input is not complete - no final space char was found
+ * @buffer: holds the parsed user input
+ * @idx: user input lenght
+ * @size: buffer size
+ */
+struct trace_parser {
+ bool cont;
+ char *buffer;
+ unsigned idx;
+ unsigned size;
+};
+
+static inline bool trace_parser_loaded(struct trace_parser *parser)
+{
+ return (parser->idx != 0);
+}
+
+static inline bool trace_parser_cont(struct trace_parser *parser)
+{
+ return parser->cont;
+}
+
+static inline void trace_parser_clear(struct trace_parser *parser)
+{
+ parser->cont = false;
+ parser->idx = 0;
+}
+
+extern int trace_parser_get_init(struct trace_parser *parser, int size);
+extern void trace_parser_put(struct trace_parser *parser);
+extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
+ size_t cnt, loff_t *ppos);
+
+/*
* trace_iterator_flags is an enumeration that defines bit
* positions into trace_flags that controls the output.
*