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authorPeter Zijlstra <peterz@infradead.org>2014-02-03 18:02:09 +0100
committerIngo Molnar <mingo@kernel.org>2014-02-09 13:17:22 +0100
commite90c78535283dd0ded3bf2e484890d14dba2d527 (patch)
tree349fe1e8b7d7dc6ea7c78a0d1403b7ca74c2f387
parent6a02ad66b2c44155d529f430d4fa5c6c66321077 (diff)
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x86/nmi: Push duration printk() to irq context
Calling printk() from NMI context is bad (TM), so move it to IRQ context. In doing so we slightly change (probably wreck) the debugfs nmi_longest_ns thingy, in that it doesn't update to reflect the longest, nor does writing to it reset the count. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Don Zickus <dzickus@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Link: http://lkml.kernel.org/n/tip-rdw0au56a5ymis1u8p48c12d@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/include/asm/nmi.h3
-rw-r--r--arch/x86/kernel/nmi.c37
2 files changed, 27 insertions, 13 deletions
diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index 86f9301903c8..5f2fc4441b11 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -1,6 +1,7 @@
#ifndef _ASM_X86_NMI_H
#define _ASM_X86_NMI_H
+#include <linux/irq_work.h>
#include <linux/pm.h>
#include <asm/irq.h>
#include <asm/io.h>
@@ -38,6 +39,8 @@ typedef int (*nmi_handler_t)(unsigned int, struct pt_regs *);
struct nmiaction {
struct list_head list;
nmi_handler_t handler;
+ u64 max_duration;
+ struct irq_work irq_work;
unsigned long flags;
const char *name;
};
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 6fcb49ce50a1..b4872b999a71 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -87,6 +87,7 @@ __setup("unknown_nmi_panic", setup_unknown_nmi_panic);
#define nmi_to_desc(type) (&nmi_desc[type])
static u64 nmi_longest_ns = 1 * NSEC_PER_MSEC;
+
static int __init nmi_warning_debugfs(void)
{
debugfs_create_u64("nmi_longest_ns", 0644,
@@ -95,6 +96,20 @@ static int __init nmi_warning_debugfs(void)
}
fs_initcall(nmi_warning_debugfs);
+static void nmi_max_handler(struct irq_work *w)
+{
+ struct nmiaction *a = container_of(w, struct nmiaction, irq_work);
+ int remainder_ns, decimal_msecs;
+ u64 whole_msecs = ACCESS_ONCE(a->max_duration);
+
+ remainder_ns = do_div(whole_msecs, (1000 * 1000));
+ decimal_msecs = remainder_ns / 1000;
+
+ printk_ratelimited(KERN_INFO
+ "INFO: NMI handler (%ps) took too long to run: %lld.%03d msecs\n",
+ a->handler, whole_msecs, decimal_msecs);
+}
+
static int __kprobes nmi_handle(unsigned int type, struct pt_regs *regs, bool b2b)
{
struct nmi_desc *desc = nmi_to_desc(type);
@@ -110,26 +125,20 @@ static int __kprobes nmi_handle(unsigned int type, struct pt_regs *regs, bool b2
* to handle those situations.
*/
list_for_each_entry_rcu(a, &desc->head, list) {
- u64 before, delta, whole_msecs;
- int remainder_ns, decimal_msecs, thishandled;
+ int thishandled;
+ u64 delta;
- before = sched_clock();
+ delta = sched_clock();
thishandled = a->handler(type, regs);
handled += thishandled;
- delta = sched_clock() - before;
+ delta = sched_clock() - delta;
trace_nmi_handler(a->handler, (int)delta, thishandled);
- if (delta < nmi_longest_ns)
+ if (delta < nmi_longest_ns || delta < a->max_duration)
continue;
- nmi_longest_ns = delta;
- whole_msecs = delta;
- remainder_ns = do_div(whole_msecs, (1000 * 1000));
- decimal_msecs = remainder_ns / 1000;
- printk_ratelimited(KERN_INFO
- "INFO: NMI handler (%ps) took too long to run: "
- "%lld.%03d msecs\n", a->handler, whole_msecs,
- decimal_msecs);
+ a->max_duration = delta;
+ irq_work_queue(&a->irq_work);
}
rcu_read_unlock();
@@ -146,6 +155,8 @@ int __register_nmi_handler(unsigned int type, struct nmiaction *action)
if (!action->handler)
return -EINVAL;
+ init_irq_work(&action->irq_work, nmi_max_handler);
+
spin_lock_irqsave(&desc->lock, flags);
/*