From 87291347c49dc40aa339f587b209618201c2e527 Mon Sep 17 00:00:00 2001 From: Vaibhav Nagarnaik Date: Thu, 13 Feb 2014 19:51:48 -0800 Subject: [PATCH] tracing: Fix array size mismatch in format string In event format strings, the array size is reported in two locations. One in array subscript and then via the "size:" attribute. The values reported there have a mismatch. For e.g., in sched:sched_switch the prev_comm and next_comm character arrays have subscript values as [32] where as the actual field size is 16. name: sched_switch ID: 301 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1;signed:0; field:int common_pid; offset:4; size:4; signed:1; field:char prev_comm[32]; offset:8; size:16; signed:1; field:pid_t prev_pid; offset:24; size:4; signed:1; field:int prev_prio; offset:28; size:4; signed:1; field:long prev_state; offset:32; size:8; signed:1; field:char next_comm[32]; offset:40; size:16; signed:1; field:pid_t next_pid; offset:56; size:4; signed:1; field:int next_prio; offset:60; size:4; signed:1; After bisection, the following commit was blamed: 92edca0 tracing: Use direct field, type and system names This commit removes the duplication of strings for field->name and field->type assuming that all the strings passed in __trace_define_field() are immutable. This is not true for arrays, where the type string is created in event_storage variable and field->type for all array fields points to event_storage. Use __stringify() to create a string constant for the type string. Also, get rid of event_storage and event_storage_mutex that are not needed anymore. also, an added benefit is that this reduces the overhead of events a bit more: text data bss dec hex filename 8424787 2036472 1302528 11763787 b3804b vmlinux 8420814 2036408 1302528 11759750 b37086 vmlinux.patched Link: http://lkml.kernel.org/r/1392349908-29685-1-git-send-email-vnagarnaik@google.com Cc: Laurent Chavey Cc: stable@vger.kernel.org # 3.10+ Signed-off-by: Vaibhav Nagarnaik Signed-off-by: Steven Rostedt --- include/linux/ftrace_event.h | 4 ---- include/trace/ftrace.h | 7 ++----- kernel/trace/trace_events.c | 6 ------ kernel/trace/trace_export.c | 7 ++----- 4 files changed, 4 insertions(+), 20 deletions(-) diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index 4e4cc28623ad..4cdb3a17bcb5 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -495,10 +495,6 @@ enum { FILTER_TRACE_FN, }; -#define EVENT_STORAGE_SIZE 128 -extern struct mutex event_storage_mutex; -extern char event_storage[EVENT_STORAGE_SIZE]; - extern int trace_event_raw_init(struct ftrace_event_call *call); extern int trace_define_field(struct ftrace_event_call *call, const char *type, const char *name, int offset, int size, diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h index 1a8b28db3775..1ee19a24cc5f 100644 --- a/include/trace/ftrace.h +++ b/include/trace/ftrace.h @@ -310,15 +310,12 @@ static struct trace_event_functions ftrace_event_type_funcs_##call = { \ #undef __array #define __array(type, item, len) \ do { \ - mutex_lock(&event_storage_mutex); \ + char *type_str = #type"["__stringify(len)"]"; \ BUILD_BUG_ON(len > MAX_FILTER_STR_VAL); \ - snprintf(event_storage, sizeof(event_storage), \ - "%s[%d]", #type, len); \ - ret = trace_define_field(event_call, event_storage, #item, \ + ret = trace_define_field(event_call, type_str, #item, \ offsetof(typeof(field), item), \ sizeof(field.item), \ is_signed_type(type), FILTER_OTHER); \ - mutex_unlock(&event_storage_mutex); \ if (ret) \ return ret; \ } while (0); diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index f3989ceb5cd5..7b16d40bd64d 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -27,12 +27,6 @@ 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); static LIST_HEAD(ftrace_common_fields); diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c index 7c3e3e72e2b6..ee0a5098ac43 100644 --- a/kernel/trace/trace_export.c +++ b/kernel/trace/trace_export.c @@ -95,15 +95,12 @@ static void __always_unused ____ftrace_check_##name(void) \ #undef __array #define __array(type, item, len) \ do { \ + char *type_str = #type"["__stringify(len)"]"; \ 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, \ + ret = trace_define_field(event_call, type_str, #item, \ offsetof(typeof(field), item), \ sizeof(field.item), \ is_signed_type(type), filter_type); \ - mutex_unlock(&event_storage_mutex); \ if (ret) \ return ret; \ } while (0); -- 2.20.1