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From: Daniel Thompson <daniel.thompson@linaro.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Daniel Thompson <daniel.thompson@linaro.org>,
	Jason Cooper <jason@lakedaemon.net>,
	Russell King <linux@arm.linux.org.uk>,
	Will Deacon <will.deacon@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Stephen Boyd <sboyd@codeaurora.org>,
	John Stultz <john.stultz@linaro.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, patches@linaro.org,
	linaro-kernel@lists.linaro.org,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Dirk Behme <dirk.behme@de.bosch.com>,
	Daniel Drake <drake@endlessm.com>,
	Dmitry Pervushin <dpervushin@gmail.com>,
	Tim Sander <tim@krieglstein.org>
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	[thread overview]
Message-ID: <1422022952-31552-9-git-send-email-daniel.thompson@linaro.org> (raw)
In-Reply-To: <1422022952-31552-1-git-send-email-daniel.thompson@linaro.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 <daniel.thompson@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <linux@arm.linux.org.uk>
---
 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


  parent reply	other threads:[~2015-01-23 14:24 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-23 14:22 [PATCH 3.19-rc2 v15 0/8] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 1/8] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 2/8] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 3/8] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 4/8] sched_clock: Avoid deadlock during read from NMI Daniel Thompson
2015-01-24 22:40   ` Thomas Gleixner
2015-01-26 20:28     ` Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 5/8] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-01-24 21:44   ` Thomas Gleixner
2015-01-26 17:21     ` Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 6/8] x86/nmi: Use common printk functions Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 7/8] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson
2015-01-23 14:22 ` Daniel Thompson [this message]
2015-02-03 19:06 ` [PATCH 3.19-rc6 v16 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 1/6] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-02-26 20:31     ` Nicolas Pitre
2015-02-26 21:05       ` Daniel Thompson
2015-02-26 21:33         ` Nicolas Pitre
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 2/6] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-02-26 20:33     ` Nicolas Pitre
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 4/6] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 5/6] x86/nmi: Use common printk functions Daniel Thompson
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 6/6] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson
2015-03-04 10:12 ` [PATCH 4.0-rc1 v17 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 1/6] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 2/6] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 4/6] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-03-04 16:13     ` Joe Perches
2015-03-04 16:20       ` Steven Rostedt
2015-03-04 16:33         ` Daniel Thompson
2015-03-04 17:21           ` Joe Perches
2015-03-05 12:11             ` Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 5/6] x86/nmi: Use common printk functions Daniel Thompson
2015-03-05  0:54     ` Ingo Molnar
2015-03-05 12:29       ` Daniel Thompson
2015-03-05 19:46         ` Ingo Molnar
2015-03-06 19:02           ` Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 6/6] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson
2015-03-12 13:39 ` [PATCH 4.0-rc2 v18 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 1/6] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 2/6] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 4/6] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 5/6] x86/nmi: Use common printk functions Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 6/6] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson

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