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.thomp...@linaro.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Russell King <li...@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
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