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Message-ID: <50BED2F0.1080809@am.sony.com>
Date: Tue, 4 Dec 2012 20:52:00 -0800
From: Frank Rowand <frank.rowand@...sony.com>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-rt-users@...r.kernel.org" <linux-rt-users@...r.kernel.org>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"paulmck@...ux.vnet.ibm.com" <paulmck@...ux.vnet.ibm.com>,
"dipankar@...ibm.com" <dipankar@...ibm.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH RT 1/2][RFC] ARM version of arch_trigger_all_cpu_backtrace()
The RCU stall warning functions print_cpu_stall() and print_other_cpu_stall()
call trigger_all_cpu_backtrace() to print a backtrace on each cpu. This
function is only implemented for x86. Add a version for ARM.
Signed-off-by: Frank Rowand <frank.rowand@...sony.com>
---
arch/arm/include/asm/hardirq.h | 2 1 + 1 - 0 !
arch/arm/include/asm/irq.h | 5 5 + 0 - 0 !
arch/arm/kernel/smp.c | 70 70 + 0 - 0 !
3 files changed, 76 insertions(+), 1 deletion(-)
Index: b/arch/arm/include/asm/irq.h
===================================================================
--- a/arch/arm/include/asm/irq.h
+++ b/arch/arm/include/asm/irq.h
@@ -30,6 +30,11 @@ extern void asm_do_IRQ(unsigned int, str
void handle_IRQ(unsigned int, struct pt_regs *);
void init_IRQ(void);
+#ifdef CONFIG_SMP
+void arch_trigger_all_cpu_backtrace(void);
+#define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace
+#endif
+
#endif
#endif
Index: b/arch/arm/kernel/smp.c
===================================================================
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -56,6 +56,7 @@ enum ipi_msg_type {
IPI_CALL_FUNC,
IPI_CALL_FUNC_SINGLE,
IPI_CPU_STOP,
+ IPI_BACKTRACE,
};
static DECLARE_COMPLETION(cpu_running);
@@ -359,6 +360,7 @@ static const char *ipi_types[NR_IPI] = {
S(IPI_CALL_FUNC, "Function call interrupts"),
S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
S(IPI_CPU_STOP, "CPU stop interrupts"),
+ S(IPI_BACKTRACE, "Trigger all cpu backtrace"),
};
void show_ipi_list(struct seq_file *p, int prec)
@@ -493,6 +495,70 @@ static void ipi_cpu_stop(unsigned int cp
cpu_relax();
}
+#ifdef arch_trigger_all_cpu_backtrace
+/*
+ * Based on arch/x86/kernel/apic/hw_nmi.c:
+ * arch_trigger_all_cpu_backtrace_handler()
+ * arch_trigger_all_cpu_backtrace()
+ */
+
+static struct cpumask backtrace_mask;
+
+static unsigned long backtrace_flag;
+static arch_spinlock_t smp_backtrace_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+
+/*
+ * ipi_backtrace - handle IPI from smp_send_backtrace()
+ */
+static void ipi_backtrace(unsigned int cpu, struct pt_regs *regs)
+{
+ /*
+ * serialize cpus
+ */
+ arch_spin_lock(&smp_backtrace_lock);
+
+ pr_crit("\nCPU %u\n", cpu);
+
+ if (regs)
+ __show_regs(regs);
+
+ dump_stack();
+
+ cpumask_clear_cpu(cpu, &backtrace_mask);
+
+ arch_spin_unlock(&smp_backtrace_lock);
+}
+
+void arch_trigger_all_cpu_backtrace(void)
+{
+ int i;
+
+ if (test_and_set_bit(0, &backtrace_flag))
+ /*
+ * If there is already a trigger_all_cpu_backtrace() in progress
+ * (backtrace_flag == 1), don't output double cpu dump infos.
+ */
+ return;
+
+ ipi_backtrace(smp_processor_id(), NULL);
+
+ cpumask_copy(&backtrace_mask, cpu_online_mask);
+ cpumask_clear_cpu(smp_processor_id(), &backtrace_mask);
+
+ if (!cpumask_empty(&backtrace_mask))
+ smp_cross_call(&backtrace_mask, IPI_BACKTRACE);
+
+ /* Wait for up to 10 seconds for all CPUs to do the backtrace */
+ for (i = 0; i < 10 * 1000; i++) {
+ if (cpumask_empty(&backtrace_mask))
+ break;
+ mdelay(1);
+ }
+
+ clear_bit(0, &backtrace_flag);
+}
+#endif
+
/*
* Main handler for inter-processor interrupts
*/
@@ -538,6 +604,10 @@ void handle_IPI(int ipinr, struct pt_reg
irq_exit();
break;
+ case IPI_BACKTRACE:
+ ipi_backtrace(cpu, regs);
+ break;
+
default:
printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
cpu, ipinr);
Index: b/arch/arm/include/asm/hardirq.h
===================================================================
--- a/arch/arm/include/asm/hardirq.h
+++ b/arch/arm/include/asm/hardirq.h
@@ -5,7 +5,7 @@
#include <linux/threads.h>
#include <asm/irq.h>
-#define NR_IPI 5
+#define NR_IPI 6
typedef struct {
unsigned int __softirq_pending;
--
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