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

Masami Hiramatsu
2009-08-27T15:04:18Z

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@cn.fujitsu.com>
> Signed-off-by: Frederic Weisbecker<fweisbec@gmail.com>
> Cc: Steven Rostedt<rostedt@goodmis.org>

Acked-by: Masami Hiramatsu <mhiramat@redhat.com>

> ---
> 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@redhat.com