From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755640AbbAWOY0 (ORCPT ); Fri, 23 Jan 2015 09:24:26 -0500 Received: from mail-wi0-f178.google.com ([209.85.212.178]:41093 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932070AbbAWOYW (ORCPT ); Fri, 23 Jan 2015 09:24:22 -0500 From: Daniel Thompson To: Thomas Gleixner Cc: Daniel Thompson , Jason Cooper , Russell King , Will Deacon , Catalin Marinas , Marc Zyngier , Stephen Boyd , John Stultz , Steven Rostedt , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, patches@linaro.org, linaro-kernel@lists.linaro.org, Sumit Semwal , Dirk Behme , Daniel Drake , Dmitry Pervushin , Tim Sander Subject: [PATCH 3.19-rc2 v15 8/8] ARM: Fix on-demand backtrace triggered by IRQ Date: Fri, 23 Jan 2015 14:22:32 +0000 Message-Id: <1422022952-31552-9-git-send-email-daniel.thompson@linaro.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1422022952-31552-1-git-send-email-daniel.thompson@linaro.org> References: <1422022952-31552-1-git-send-email-daniel.thompson@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently if arch_trigger_all_cpu_backtrace() is called with interrupts disabled and on a platform the delivers IPI_CPU_BACKTRACE using regular IRQ requests the system will wedge for ten seconds waiting for the current CPU to react to a masked interrupt. This patch resolves this issue by calling directly into the backtrace dump code instead of generating an IPI. Signed-off-by: Daniel Thompson Cc: Steven Rostedt Cc: Russell King --- arch/arm/kernel/smp.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 93fe51d305d1..ef35cf832aee 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -739,6 +739,16 @@ void arch_trigger_all_cpu_backtrace(bool include_self) cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask)); cpumask_copy(&printtrace_mask, to_cpumask(backtrace_mask)); + /* + * If irqs are disabled on the current processor then, if + * IPI_CPU_BACKTRACE is delivered using IRQ, we will won't be able to + * react to IPI_CPU_BACKTRACE until we leave this function. We avoid + * the potential timeout (not to mention the failure to print useful + * information) by calling the backtrace directly. + */ + if (include_self && irqs_disabled()) + ipi_cpu_backtrace(in_interrupt() ? get_irq_regs() : NULL); + if (!cpumask_empty(to_cpumask(backtrace_mask))) { pr_info("Sending FIQ to %s CPUs:\n", (include_self ? "all" : "other")); @@ -767,7 +777,10 @@ void ipi_cpu_backtrace(struct pt_regs *regs) if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { orig = this_cpu_begin_nmi_printk(); pr_warn("FIQ backtrace for cpu %d\n", cpu); - show_regs(regs); + if (regs != NULL) + show_regs(regs); + else + dump_stack(); this_cpu_end_nmi_printk(orig); cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); -- 1.9.3