Re: [PATCH 2/7] powerpc/traps: Return early in show_signal_msg()

LEROY Christophe
2018-07-25T15:42:33Z

Murilo Opsfelder Araujo <muriloo@linux.ibm.com> a écrit :

> Modify logic of show_signal_msg() to return early, if possible. Replace
> printk_ratelimited() by printk() and a default rate limit burst to limit
> displaying unhandled signals messages.

Can you explain more the benefits of this change ?

Christophe

>
> Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
> ---
> arch/powerpc/kernel/traps.c | 21 +++++++++++++++------
> 1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index cbd3dc365193..4faab4705774 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -301,6 +301,13 @@ void user_single_step_siginfo(struct task_struct *tsk,
> info->si_addr = (void __user *)regs->nip;
> }
>
> +static bool show_unhandled_signals_ratelimited(void)
> +{
> + 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)
> {
> @@ -309,11 +316,12 @@ static void show_signal_msg(int signr, struct
> pt_regs *regs, int code,
> const char fmt64[] = KERN_INFO "%s[%d]: unhandled signal %d " \
> "at %016lx nip %016lx lr %016lx code %x\n";
>
> - if (show_unhandled_signals && unhandled_signal(current, signr)) {
> - printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
> - current->comm, current->pid, signr,
> - addr, regs->nip, regs->link, code);
> - }
> + if (!unhandled_signal(current, signr))
> + return;
> +
> + printk(regs->msr & MSR_64BIT ? fmt64 : fmt32,
> + current->comm, current->pid, signr,
> + addr, regs->nip, regs->link, code);
> }
>
> void _exception_pkey(int signr, struct pt_regs *regs, int code,
> @@ -326,7 +334,8 @@ void _exception_pkey(int signr, struct pt_regs
> *regs, int code,
> return;
> }
>
> - show_signal_msg(signr, regs, code, addr);
> + if (show_unhandled_signals_ratelimited())
> + show_signal_msg(signr, regs, code, addr);
>
> if (arch_irqs_disabled() && !arch_irq_disabled_regs(regs))
> local_irq_enable();
> --
> 2.17.1