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SubjectRe: [PATCH] TRACING: Fix a copmile warning
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On Mon, 2011-07-18 at 17:40 +0800, stufever@gmail.com wrote:
> From: Wang Shaoyan <wangshaoyan.pt@taobao.com>
>
> It's harmless but annyoing.
> kernel/trace/trace_printk.c: In function 'module_trace_bprintk_format_notify':
> kernel/trace/trace_printk.c:52: warning: 'fmt' may be used uninitialized in this function

I prefer not to add this patch. Fix gcc. Actually some gcc's do not warn
on this, others do. Here's the code that confuses gcc:

tb_fmt = kmalloc(sizeof(*tb_fmt), GFP_KERNEL);
if (tb_fmt)
fmt = kmalloc(strlen(*iter) + 1, GFP_KERNEL);
if (tb_fmt && fmt) {
list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list);
strcpy(fmt, *iter);
tb_fmt->fmt = fmt;
*iter = tb_fmt->fmt;


fmt will never be looked at if tb_fmt is NULL, and fmt is initialized if
tb_fmt is not NULL.

-- Steve

>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Signed-off-by: Wang Shaoyan <wangshaoyan.pt@taobao.com>
>
> ---
> kernel/trace/trace_printk.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
> index 1f06468..1a5fff8 100644
> --- a/kernel/trace/trace_printk.c
> +++ b/kernel/trace/trace_printk.c
> @@ -49,7 +49,7 @@ static
> void hold_module_trace_bprintk_format(const char **start, const char **end)
> {
> const char **iter;
> - char *fmt;
> + char *fmt = NULL;
>
> mutex_lock(&btrace_mutex);
> for (iter = start; iter < end; iter++) {




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