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Date: Wed, 23 Apr 2014 16:40:04 -0400
From: Don Zickus <dzickus@...hat.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: akpm@...ux-foundation.org, x86@...nel.org, davem@...emloft.net,
sparclinux@...r.kernel.org, mguzik@...hat.com,
Aaron Tomlin <atomlin@...hat.com>,
Don Zickus <dzickus@...hat.com>
Subject: [PATCH 1/2 v4] nmi: Provide the option to issue an NMI back trace to every cpu but current
From: Aaron Tomlin <atomlin@...hat.com>
Some times it is preferred not to use the
trigger_all_cpu_backtrace() routine when one wants
to avoid capturing a back trace for current.
For instance if one was previously captured
recently.
This patch provides a new routine namely
trigger_allbutself_cpu_backtrace() which offers
the flexibility to issue an NMI to every cpu but
current and capture a back trace accordingly.
Patched x86 and sparc to support new routine.
Acked-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Aaron Tomlin <atomlin@...hat.com>
[Added stub in #else clause]
[Don't print message in single processor case,
wrap with get/put_cpu based on Oleg's suggestion]
Signed-off-by: Don Zickus <dzickus@...hat.com>
---
arch/sparc/include/asm/irq_64.h | 2 +-
arch/sparc/kernel/process_64.c | 14 +++++++++-----
arch/x86/include/asm/irq.h | 2 +-
arch/x86/kernel/apic/hw_nmi.c | 17 +++++++++++++----
include/linux/nmi.h | 11 ++++++++++-
5 files changed, 34 insertions(+), 12 deletions(-)
diff --git a/arch/sparc/include/asm/irq_64.h b/arch/sparc/include/asm/irq_64.h
index abf6afe..4f072b9 100644
--- a/arch/sparc/include/asm/irq_64.h
+++ b/arch/sparc/include/asm/irq_64.h
@@ -89,7 +89,7 @@ static inline unsigned long get_softint(void)
return retval;
}
-void arch_trigger_all_cpu_backtrace(void);
+void arch_trigger_all_cpu_backtrace(bool);
#define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace
extern void *hardirq_stack[NR_CPUS];
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 32a280e..3d61b98 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -237,7 +237,7 @@ static void __global_reg_poll(struct global_reg_snapshot *gp)
}
}
-void arch_trigger_all_cpu_backtrace(void)
+void arch_trigger_all_cpu_backtrace(bool include_self)
{
struct thread_info *tp = current_thread_info();
struct pt_regs *regs = get_irq_regs();
@@ -249,15 +249,19 @@ void arch_trigger_all_cpu_backtrace(void)
spin_lock_irqsave(&global_cpu_snapshot_lock, flags);
- memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));
-
this_cpu = raw_smp_processor_id();
- __global_reg_self(tp, regs, this_cpu);
+ memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));
+
+ if (include_self)
+ __global_reg_self(tp, regs, this_cpu);
smp_fetch_global_regs();
for_each_online_cpu(cpu) {
+ if (!include_self && cpu == this_cpu)
+ continue;
+
struct global_reg_snapshot *gp = &global_cpu_snapshot[cpu].reg;
__global_reg_poll(gp);
@@ -290,7 +294,7 @@ void arch_trigger_all_cpu_backtrace(void)
static void sysrq_handle_globreg(int key)
{
- arch_trigger_all_cpu_backtrace();
+ arch_trigger_all_cpu_backtrace(true);
}
static struct sysrq_key_op sparc_globalreg_op = {
diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h
index cb6cfcd..a80cbb8 100644
--- a/arch/x86/include/asm/irq.h
+++ b/arch/x86/include/asm/irq.h
@@ -43,7 +43,7 @@ extern int vector_used_by_percpu_irq(unsigned int vector);
extern void init_ISA_irqs(void);
#ifdef CONFIG_X86_LOCAL_APIC
-void arch_trigger_all_cpu_backtrace(void);
+void arch_trigger_all_cpu_backtrace(bool);
#define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace
#endif
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index a698d71..1400d72 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -33,31 +33,40 @@ static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
/* "in progress" flag of arch_trigger_all_cpu_backtrace */
static unsigned long backtrace_flag;
-void arch_trigger_all_cpu_backtrace(void)
+void arch_trigger_all_cpu_backtrace(bool include_self)
{
int i;
+ int cpu = get_cpu();
- if (test_and_set_bit(0, &backtrace_flag))
+ 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.
*/
+ put_cpu();
return;
+ }
cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
+ if (!include_self)
+ cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
- printk(KERN_INFO "sending NMI to all CPUs:\n");
- apic->send_IPI_all(NMI_VECTOR);
+ if (!cpumask_empty(to_cpumask(backtrace_mask))) {
+ pr_info("sending NMI to %s CPUs:\n", (include_self ? "all" : "other"));
+ apic->send_IPI_mask(to_cpumask(backtrace_mask), NMI_VECTOR);
+ }
/* Wait for up to 10 seconds for all CPUs to do the backtrace */
for (i = 0; i < 10 * 1000; i++) {
if (cpumask_empty(to_cpumask(backtrace_mask)))
break;
mdelay(1);
+ touch_softlockup_watchdog();
}
clear_bit(0, &backtrace_flag);
smp_mb__after_clear_bit();
+ put_cpu();
}
static int __kprobes
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 6a45fb5..a17ab63 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -32,15 +32,24 @@ static inline void touch_nmi_watchdog(void)
#ifdef arch_trigger_all_cpu_backtrace
static inline bool trigger_all_cpu_backtrace(void)
{
- arch_trigger_all_cpu_backtrace();
+ arch_trigger_all_cpu_backtrace(true);
return true;
}
+static inline bool trigger_allbutself_cpu_backtrace(void)
+{
+ arch_trigger_all_cpu_backtrace(false);
+ return true;
+}
#else
static inline bool trigger_all_cpu_backtrace(void)
{
return false;
}
+static inline bool trigger_allbutself_cpu_backtrace(void)
+{
+ return false;
+}
#endif
#ifdef CONFIG_LOCKUP_DETECTOR
--
1.7.1
--
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