Re: [PATCH] trace, kasan: silence Kasan warning in check_stack

[Shi, Yang]

On 2/12/2016 11:35 AM, Steven Rostedt wrote:
> On Mon,  8 Feb 2016 10:39:42 -0800
> Yang Shi <yang.shi@xxxxxxxxxx> wrote:
>
> > Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxx>
> > ---
> >   kernel/trace/trace_stack.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
> > index 202df6c..61e5e1e 100644
> > --- a/kernel/trace/trace_stack.c
> > +++ b/kernel/trace/trace_stack.c
> > @@ -156,7 +156,7 @@ check_stack(unsigned long ip, unsigned long *stack)
> >   		for (; p < top && i < stack_trace_max.nr_entries; p++) {
> >   			if (stack_dump_trace[i] == ULONG_MAX)
> >   				break;
> > -			if (*p == stack_dump_trace[i]) {
>
> Can you add a comment explaining this. Something like:
>
> 	/*
> 	 * The READ_ONCE_NOCHECK() is used to let KASAN know that
> 	 * this is not an stack-out-of-bounds error.
> 	 */

Sure, will add in v2.

Thanks,
Yang

> Thanks,
>
> -- Steve
>
> > +			if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) {
> >   				stack_dump_trace[x] = stack_dump_trace[i++];
> >   				this_size = stack_trace_index[x++] =
> >   					(top - p) * sizeof(unsigned long);