Re: [PATCH v3 14/15] powerpc/64s: system reset do not trace

[Christophe Leroy <christophe.leroy@c-s.fr>]

Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :
> Similarly to the previous patch, do not trace system reset. This code
> is used when there is a crash or hang, and tracing disturbs the system
> more and has been known to crash in the crash handling path.
> 
> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>

> ---
>   arch/powerpc/kernel/traps.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 9f221772eb73..1beae89bb871 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -443,6 +443,9 @@ void system_reset_exception(struct pt_regs *regs)
>   	unsigned long hsrr0, hsrr1;
>   	bool nested = in_nmi();
>   	bool saved_hsrrs = false;
> +	u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
> +
> +	this_cpu_set_ftrace_enabled(0);
>   
>   	/*
>   	 * Avoid crashes in case of nested NMI exceptions. Recoverability
> @@ -524,6 +527,8 @@ void system_reset_exception(struct pt_regs *regs)
>   	if (!nested)
>   		nmi_exit();
>   
> +	this_cpu_set_ftrace_enabled(ftrace_enabled);
> +
>   	/* What should we do here? We could issue a shutdown or hard reset. */
>   }
>   
>