lkml.org 
[lkml]   [2009]   [May]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 1/3] tracing: add __print_flags for events
From: Steven Rostedt <srostedt@redhat.com>

Developers have been asking for the ability in the ftrace event tracer
to display names of bits in a flags variable.

Instead of printing out c2, it would be easier to read FOO|BAR|GOO,
assuming that FOO is bit 1, BAR is bit 6 and GOO is bit 7.
Some examples where this would be useful are the state flags in a context
switch, kmalloc flags, and even permision flags in accessing files.

I included Frederic Weisbecker's idea of using a mask instead of bits,
thus we can output GFP_KERNEL instead of GPF_WAIT|GFP_IO|GFP_FS.
I also included Li Zefan's idea of allowing the caller of __print_flags
to add their own delimiter (or no delimiter) where we can get for
file permissions rwx instead of r|w|x.
[ Impact: better displaying of flags in trace output ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/ftrace_event.h | 6 +++++-
include/trace/ftrace.h | 10 ++++++++++
kernel/trace/trace_output.c | 38 ++++++++++++++++++++++++++++++++++++++
3 files changed, 53 insertions(+), 1 deletions(-)
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index bae51dd..253c3d0 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -3,12 +3,16 @@

#include <linux/trace_seq.h>
#include <linux/ring_buffer.h>
-
+#include <linux/percpu.h>

struct trace_array;
struct tracer;
struct dentry;

+DECLARE_PER_CPU(struct trace_seq, ftrace_event_seq);
+const char *ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
+ unsigned long flags, ...);
+
/*
* The trace entry - the most basic unit of tracing. This is what
* is printed in the end as a single line in the trace output, such as:
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index edb02bc..9b79c7c 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -87,6 +87,7 @@
* struct trace_seq *s = &iter->seq;
* struct ftrace_raw_<call> *field; <-- defined in stage 1
* struct trace_entry *entry;
+ * struct trace_seq *p;
* int ret;
*
* entry = iter->ent;
@@ -98,7 +99,9 @@
*
* field = (typeof(field))entry;
*
+ * p = get_cpu_var(ftrace_event_seq);
* ret = trace_seq_printf(s, <TP_printk> "\n");
+ * put_cpu();
* if (!ret)
* return TRACE_TYPE_PARTIAL_LINE;
*
@@ -119,6 +122,10 @@
#undef __get_str
#define __get_str(field) ((char *)__entry + __entry->__str_loc_##field)

+#undef __print_flags
+#define __print_flags(flag, delim, x...) \
+ ftrace_print_flags_seq(p, delim, flag, x , 0)
+
#undef TRACE_EVENT
#define TRACE_EVENT(call, proto, args, tstruct, assign, print) \
enum print_line_t \
@@ -127,6 +134,7 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags) \
struct trace_seq *s = &iter->seq; \
struct ftrace_raw_##call *field; \
struct trace_entry *entry; \
+ struct trace_seq *p; \
int ret; \
\
entry = iter->ent; \
@@ -138,7 +146,9 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags) \
\
field = (typeof(field))entry; \
\
+ p = &get_cpu_var(ftrace_event_seq); \
ret = trace_seq_printf(s, #call ": " print); \
+ put_cpu(); \
if (!ret) \
return TRACE_TYPE_PARTIAL_LINE; \
\
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 489c0e8..f730de5 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -14,6 +14,8 @@
/* must be a power of 2 */
#define EVENT_HASHSIZE 128

+DEFINE_PER_CPU(struct trace_seq, ftrace_event_seq);
+
static DEFINE_MUTEX(trace_event_mutex);
static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;

@@ -212,6 +214,42 @@ int trace_seq_path(struct trace_seq *s, struct path *path)
return 0;
}

+const char *
+ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
+ unsigned long flags, ...)
+{
+ const char *str;
+ va_list args;
+ unsigned long mask;
+
+ trace_seq_init(p);
+ va_start(args, flags);
+ for (mask = va_arg(args, unsigned long); mask && flags;
+ mask = va_arg(args, unsigned long)) {
+ str = va_arg(args, const char *);
+
+ if ((flags & mask) != mask)
+ continue;
+
+ flags &= ~mask;
+ if (p->len && delim)
+ trace_seq_puts(p, delim);
+ trace_seq_puts(p, str);
+ }
+ va_end(args);
+
+ /* check for left over flags */
+ if (flags) {
+ if (p->len && delim)
+ trace_seq_puts(p, delim);
+ trace_seq_printf(p, "0x%lx", flags);
+ }
+
+ trace_seq_putc(p, 0);
+
+ return p->buffer;
+}
+
#ifdef CONFIG_KRETPROBES
static inline const char *kretprobed(const char *name)
{
--
1.6.2.4
--


\
 
 \ /
  Last update: 2009-05-15 23:13    [from the cache]
©2003-2011 Jasper Spaans