tracing: Use TRACE_FLAGS macro to keep enums and strings matched
Use a cute little macro trick to keep the names of the trace flags file
guaranteed to match the corresponding masks.
The macro TRACE_FLAGS is defined as a serious of enum names followed by
the string name of the file that matches it. For example:
#define TRACE_FLAGS \
C(PRINT_PARENT, "print-parent"), \
C(SYM_OFFSET, "sym-offset"), \
C(SYM_ADDR, "sym-addr"), \
C(VERBOSE, "verbose"),
Now we can define the following:
#undef C
#define C(a, b) TRACE_ITER_##a##_BIT
enum trace_iterator_bits { TRACE_FLAGS };
The above creates:
enum trace_iterator_bits {
TRACE_ITER_PRINT_PARENT_BIT,
TRACE_ITER_SYM_OFFSET_BIT,
TRACE_ITER_SYM_ADDR_BIT,
TRACE_ITER_VERBOSE_BIT,
};
Then we can redefine C as:
#undef C
#define C(a, b) TRACE_ITER_##a = (1 << TRACE_ITER_##a##_BIT)
enum trace_iterator_flags { TRACE_FLAGS };
Which creates:
enum trace_iterator_flags {
TRACE_ITER_PRINT_PARENT = (1 << TRACE_ITER_PRINT_PARENT_BIT),
TRACE_ITER_SYM_OFFSET = (1 << TRACE_ITER_SYM_OFFSET_BIT),
TRACE_ITER_SYM_ADDR = (1 << TRACE_ITER_SYM_ADDR_BIT),
TRACE_ITER_VERBOSE = (1 << TRACE_ITER_VERBOSE_BIT),
};
Then finally we can create the list of file names:
#undef C
#define C(a, b) b
static const char *trace_options[] = {
TRACE_FLAGS
NULL
};
Which creates:
static const char *trace_options[] = {
"print-parent",
"sym-offset",
"sym-addr",
"verbose",
NULL
};
The importance of this is that the strings match the bit index.
trace_options[TRACE_ITER_SYM_ADDR_BIT] == "sym-addr"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f2fbf61..e80e380 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -854,34 +854,18 @@
return nsecs / 1000;
}
+/*
+ * TRACE_FLAGS is defined as a tuple matching bit masks with strings.
+ * It uses C(a, b) where 'a' is the enum name and 'b' is the string that
+ * matches it. By defining "C(a, b) b", TRACE_FLAGS becomes a list
+ * of strings in the order that the enums were defined.
+ */
+#undef C
+#define C(a, b) b
+
/* These must match the bit postions in trace_iterator_flags */
static const char *trace_options[] = {
- "print-parent",
- "sym-offset",
- "sym-addr",
- "verbose",
- "raw",
- "hex",
- "bin",
- "block",
- "stacktrace",
- "trace_printk",
- "branch",
- "annotate",
- "userstacktrace",
- "sym-userobj",
- "printk-msg-only",
- "context-info",
- "latency-format",
- "sleep-time",
- "graph-time",
- "record-cmd",
- "overwrite",
- "disable_on_free",
- "irq-info",
- "markers",
- "function-trace",
- "display-graph",
+ TRACE_FLAGS
NULL
};