From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-x244.google.com (mail-pl0-x244.google.com [IPv6:2607:f8b0:400e:c01::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40DWxF2C48zF20w for ; Sun, 1 Apr 2018 20:36:33 +1000 (AEST) Received: by mail-pl0-x244.google.com with SMTP id 61-v6so559430plb.2 for ; Sun, 01 Apr 2018 03:36:33 -0700 (PDT) From: Nicholas Piggin To: linuxppc-dev@lists.ozlabs.org Cc: Nicholas Piggin , Vasant Hegde Subject: [PATCH v2 1/3] powerpc: use NMI IPI for smp_send_stop Date: Sun, 1 Apr 2018 20:36:13 +1000 Message-Id: <20180401103615.15454-2-npiggin@gmail.com> In-Reply-To: <20180401103615.15454-1-npiggin@gmail.com> References: <20180401103615.15454-1-npiggin@gmail.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Use the NMI IPI rather than smp_call_function for smp_send_stop. Have stopped CPUs hard disable interrupts rather than just soft disable. This function is used in crash/panic/shutdown paths to bring other CPUs down as quickly and reliably as possible, and minimizing their potential to cause trouble. Avoiding the Linux smp_call_function infrastructure and (if supported) using true NMI IPIs makes this more robust. Signed-off-by: Nicholas Piggin --- arch/powerpc/kernel/smp.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index cfc08b099c49..db88660bf6bd 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -565,7 +565,11 @@ void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *)) } #endif +#ifdef CONFIG_NMI_IPI +static void stop_this_cpu(struct pt_regs *regs) +#else static void stop_this_cpu(void *dummy) +#endif { /* Remove this CPU */ set_cpu_online(smp_processor_id(), false); @@ -577,7 +581,11 @@ static void stop_this_cpu(void *dummy) void smp_send_stop(void) { +#ifdef CONFIG_NMI_IPI + smp_send_nmi_ipi(NMI_IPI_ALL_OTHERS, stop_this_cpu, 1000000); +#else smp_call_function(stop_this_cpu, NULL, 0); +#endif } struct thread_info *current_set[NR_CPUS]; -- 2.16.3