Hi, Michael.
On Fri, Aug 17, 2018 at 04:55:00PM +1000, Michael Ellerman wrote:
> In the recent commit to add an explicit ratelimit state when showing
> unhandled signals, commit 35a52a10c3ac ("powerpc/traps: Use an
> explicit ratelimit state for show_signal_msg()"), I put the check of
> show_unhandled_signals and the ratelimit state before the call to
> unhandled_signal() so as to avoid unnecessarily calling the latter
> when show_unhandled_signals is false.
>
> However that causes us to check the ratelimit state on every call, so
> if we take a lot of *handled* signals that has the effect of making
> the ratelimit code print warnings that callbacks have been suppressed
> when they haven't.
>
> So rearrange the code so that we check show_unhandled_signals first,
> then call unhandled_signal() and finally check the ratelimit state.
>
> Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Nice catch. Thanks for patching it.
Reviewed-by: Murilo Opsfelder Araujo <muri...@linux.ibm.com>
> ---
> arch/powerpc/kernel/traps.c | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 070e96f1773a..c85adb858271 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -315,22 +315,21 @@ void user_single_step_siginfo(struct task_struct *tsk,
> info->si_addr = (void __user *)regs->nip;
> }
>
> -static bool show_unhandled_signals_ratelimited(void)
> +static void show_signal_msg(int signr, struct pt_regs *regs, int code,
> + unsigned long addr)
> {
> static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
> DEFAULT_RATELIMIT_BURST);
> - return show_unhandled_signals && __ratelimit(&rs);
> -}
>
> -static void show_signal_msg(int signr, struct pt_regs *regs, int code,
> - unsigned long addr)
> -{
> - if (!show_unhandled_signals_ratelimited())
> + if (!show_unhandled_signals)
> return;
>
> if (!unhandled_signal(current, signr))
> return;
>
> + if (!__ratelimit(&rs))
> + return;
> +
> pr_info("%s[%d]: %s (%d) at %lx nip %lx lr %lx code %x",
> current->comm, current->pid, signame(signr), signr,
> addr, regs->nip, regs->link, code);
> --
> 2.17.1
>
--
Murilo
