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authorSteven Rostedt <srostedt@redhat.com>2010-11-12 22:32:11 -0500
committerSteven Rostedt <rostedt@goodmis.org>2010-11-19 10:18:47 -0500
commit042957801626465492b9428860de39a3cb2a8219 (patch)
treeb0997862babd5e474c500b1b4c522f3a03842106 /kernel/trace
parent45677454dd6d128608117abe7dcd2bdfdd7cdf72 (diff)
downloadlinux-042957801626465492b9428860de39a3cb2a8219.tar.bz2
tracing/events: Show real number in array fields
Currently we have in something like the sched_switch event: field:char prev_comm[TASK_COMM_LEN]; offset:12; size:16; signed:1; When a userspace tool such as perf tries to parse this, the TASK_COMM_LEN is meaningless. This is done because the TRACE_EVENT() macro simply uses a #len to show the string of the length. When the length is an enum, we get a string that means nothing for tools. By adding a static buffer and a mutex to protect it, we can store the string into that buffer with snprintf and show the actual number. Now we get: field:char prev_comm[16]; offset:12; size:16; signed:1; Something much more useful. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace_events.c6
-rw-r--r--kernel/trace/trace_export.c14
2 files changed, 16 insertions, 4 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 0725eeab1937..35fde09b81de 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -27,6 +27,12 @@
DEFINE_MUTEX(event_mutex);
+DEFINE_MUTEX(event_storage_mutex);
+EXPORT_SYMBOL_GPL(event_storage_mutex);
+
+char event_storage[EVENT_STORAGE_SIZE];
+EXPORT_SYMBOL_GPL(event_storage);
+
LIST_HEAD(ftrace_events);
LIST_HEAD(ftrace_common_fields);
diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
index 4ba44deaac25..4b74d71705c0 100644
--- a/kernel/trace/trace_export.c
+++ b/kernel/trace/trace_export.c
@@ -83,13 +83,19 @@ static void __always_unused ____ftrace_check_##name(void) \
#undef __array
#define __array(type, item, len) \
- BUILD_BUG_ON(len > MAX_FILTER_STR_VAL); \
- ret = trace_define_field(event_call, #type "[" #len "]", #item, \
+ do { \
+ BUILD_BUG_ON(len > MAX_FILTER_STR_VAL); \
+ mutex_lock(&event_storage_mutex); \
+ snprintf(event_storage, sizeof(event_storage), \
+ "%s[%d]", #type, len); \
+ ret = trace_define_field(event_call, event_storage, #item, \
offsetof(typeof(field), item), \
sizeof(field.item), \
is_signed_type(type), FILTER_OTHER); \
- if (ret) \
- return ret;
+ mutex_unlock(&event_storage_mutex); \
+ if (ret) \
+ return ret; \
+ } while (0);
#undef __array_desc
#define __array_desc(type, container, item, len) \