Hello Steven
Would you review the patch?
On 2019/06/30 17:54, Eiichi Tsukata wrote:
> Commit c5c27a0a5838 ("x86/stacktrace: Remove the pointless ULONG_MAX
> marker") removes ULONG_MAX marker from user stack trace entries but
> trace_user_stack_print() still uses the marker and it outputs unnecessary
> "??".
>
> For example:
>
> less-1911 [001] d..2 34.758944: <user stack trace>
> => <00007f16f2295910>
> => ??
> => ??
> => ??
> => ??
> => ??
> => ??
> => ??
>
> The user stack trace code zeroes the storage before saving the stack, so if
> the trace is shorter than the maximum number of entries it can terminate
> the print loop if a zero entry is detected.
>
> Fixes: 4285f2fcef80 ("tracing: Remove the ULONG_MAX stack trace hackery")
> Signed-off-by: Eiichi Tsukata <[email protected]>
> ---
> kernel/trace/trace_output.c | 9 +--------
> 1 file changed, 1 insertion(+), 8 deletions(-)
>
> diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> index ba751f993c3b..cab4a5398f1d 100644
> --- a/kernel/trace/trace_output.c
> +++ b/kernel/trace/trace_output.c
> @@ -1109,17 +1109,10 @@ static enum print_line_t
> trace_user_stack_print(struct trace_iterator *iter,
> for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
> unsigned long ip = field->caller[i];
>
> - if (ip == ULONG_MAX || trace_seq_has_overflowed(s))
> + if (!ip || trace_seq_has_overflowed(s))
> break;
>
> trace_seq_puts(s, " => ");
> -
> - if (!ip) {
> - trace_seq_puts(s, "??");
> - trace_seq_putc(s, '\n');
> - continue;
> - }
> -
> seq_print_user_ip(s, mm, ip, flags);
> trace_seq_putc(s, '\n');
> }
>
