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Date: Mon, 5 Aug 2013 11:04:41 +0800
From: "zhangwei(Jovi)" <jovi.zhangwei@...wei.com>
To: Steven Rostedt <rostedt@...dmis.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Ingo Molnar <mingo@...hat.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tracing: fix wrong output of the __array field type string
On 2013/7/27 14:35, zhangwei(Jovi) wrote:
> A bug was found in events/sched/sched_switch/format.
>
> field:char prev_comm[32]; offset:8; size:16; signed:1;
>
> and prev_comm field is defined as:
>
> __array( char, prev_comm, TASK_COMM_LEN )
>
> Note TASK_COMM_LEN is 16, but the arrary len is 32 in there.
>
> The root cause is we use global temp buffer event_storage as
> constant type string in trace_define_field function when
> define __array field, this will make old field type string
> flushed by new string in event_storage.
>
> In this patch, type string is checked by core_kernel_data firstly,
> if it's not core kernel data, then copy the storage.
>
> This patch also kill the global storage event_storage.
>
> events/sched/sched_switch/format changed after patch:
>
> field:char prev_comm[16]; offset:8; size:16; signed:1;
>
Ping...
> Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@...wei.com>
> ---
> include/linux/ftrace_event.h | 2 --
> include/trace/ftrace.h | 4 ++--
> kernel/trace/trace_events.c | 20 +++++++++++++-------
> kernel/trace/trace_export.c | 4 ++--
> 4 files changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
> index 4372658..bd91f0e 100644
> --- a/include/linux/ftrace_event.h
> +++ b/include/linux/ftrace_event.h
> @@ -324,8 +324,6 @@ enum {
> };
>
> #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,
> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
> index d615f78..c8bd295 100644
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -303,7 +303,8 @@ static struct trace_event_functions ftrace_event_type_funcs_##call = { \
> #undef __array
> #define __array(type, item, len) \
> do { \
> - mutex_lock(&event_storage_mutex); \
> + char event_storage[EVENT_STORAGE_SIZE]; \
> + \
> BUILD_BUG_ON(len > MAX_FILTER_STR_VAL); \
> snprintf(event_storage, sizeof(event_storage), \
> "%s[%d]", #type, len); \
> @@ -311,7 +312,6 @@ static struct trace_event_functions ftrace_event_type_funcs_##call = { \
> 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 5f694ce..5827287 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);
>
> @@ -100,7 +94,15 @@ static int __trace_define_field(struct list_head *head, const char *type,
> goto err;
>
> field->name = name;
> - field->type = type;
> +
> + /* for __array field, type is not a constant string */
> + if (!core_kernel_data((unsigned long)type)) {
> + field->type = kstrdup(type, GFP_KERNEL);
> + if (!field->type)
> + goto err;
> + } else {
> + field->type = type;
> + }
>
> if (filter_type == FILTER_OTHER)
> field->filter_type = filter_assign_type(type);
> @@ -166,6 +168,10 @@ static void trace_destroy_fields(struct ftrace_event_call *call)
> head = trace_get_fields(call);
> list_for_each_entry_safe(field, next, head, link) {
> list_del(&field->link);
> +
> + if (!core_kernel_data((unsigned long)field->type))
> + kfree(field->type);
> +
> kmem_cache_free(field_cachep, field);
> }
> }
> diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
> index d21a746..490eb32 100644
> --- a/kernel/trace/trace_export.c
> +++ b/kernel/trace/trace_export.c
> @@ -95,15 +95,15 @@ static void __always_unused ____ftrace_check_##name(void) \
> #undef __array
> #define __array(type, item, len) \
> do { \
> + char event_storage[EVENT_STORAGE_SIZE]; \
> + \
> 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_type); \
> - mutex_unlock(&event_storage_mutex); \
> if (ret) \
> return ret; \
> } while (0);
>
--
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