Re: [PATCH 19/18] tracing: Restore the const qualifier for fieldnames and types definition

[Masami Hiramatsu]

Frederic Weisbecker wrote:
> Restore the const qualifier in field's name and type parameters of
> trace_define_field that was lost while solving a conflict.
> 
> Fields names and types are defined as builtin constant strings in
> static TRACE_EVENTs. But kprobes allocates these dynamically.
> 
> That said, we still want to always pass these strings as const char *
> in trace_define_fields() to avoid any further accidental writes on
> the pointed strings.
> 
> Reported-by: Li Zefan<lizf@xxxxxxxxxxxxxx>
> Signed-off-by: Frederic Weisbecker<fweisbec@xxxxxxxxx>
> Cc: Steven Rostedt<rostedt@xxxxxxxxxxx>

Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>

> ---
>   include/linux/ftrace_event.h  |    6 +++---
>   kernel/trace/trace_events.c   |    4 ++--
>   kernel/trace/trace_syscalls.c |    4 ++--
>   3 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
> index 1ab3089..73edf5a 100644
> --- a/include/linux/ftrace_event.h
> +++ b/include/linux/ftrace_event.h
> @@ -148,9 +148,9 @@ enum {
>   };
> 
>   extern int trace_define_common_fields(struct ftrace_event_call *call);
> -extern int trace_define_field(struct ftrace_event_call *call, char *type,
> -			      char *name, int offset, int size, int is_signed,
> -			      int filter_type);
> +extern int trace_define_field(struct ftrace_event_call *call, const char *type,
> +			      const char *name, int offset, int size,
> +			      int is_signed, int filter_type);
>   extern int trace_add_event_call(struct ftrace_event_call *call);
>   extern void trace_remove_event_call(struct ftrace_event_call *call);
> 
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 8079bb5..197cdaa 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -27,8 +27,8 @@ DEFINE_MUTEX(event_mutex);
> 
>   LIST_HEAD(ftrace_events);
> 
> -int trace_define_field(struct ftrace_event_call *call, char *type,
> -		       char *name, int offset, int size, int is_signed,
> +int trace_define_field(struct ftrace_event_call *call, const char *type,
> +		       const char *name, int offset, int size, int is_signed,
>   		       int filter_type)
>   {
>   	struct ftrace_event_field *field;
> diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
> index 5931933..a928dd0 100644
> --- a/kernel/trace/trace_syscalls.c
> +++ b/kernel/trace/trace_syscalls.c
> @@ -193,8 +193,8 @@ int syscall_enter_define_fields(struct ftrace_event_call *call)
>   		return ret;
> 
>   	for (i = 0; i<  meta->nb_args; i++) {
> -		ret = trace_define_field(call, (char *)meta->types[i],
> -					 (char *)meta->args[i], offset,
> +		ret = trace_define_field(call, meta->types[i],
> +					 meta->args[i], offset,
>   					 sizeof(unsigned long), 0,
>   					 FILTER_OTHER);
>   		offset += sizeof(unsigned long);

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@xxxxxxxxxx

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