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>

1 files changed, 35 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b69697b4b846..28247cecd955 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.
  *