Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753367AbaBJN34 (ORCPT ); Mon, 10 Feb 2014 08:29:56 -0500 Received: from terminus.zytor.com ([198.137.202.10]:33119 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752662AbaBJN3w (ORCPT ); Mon, 10 Feb 2014 08:29:52 -0500 Date: Mon, 10 Feb 2014 05:29:17 -0800 From: tip-bot for Peter Zijlstra Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, dave.hansen@linux.intel.com, tglx@linutronix.de, dzickus@redhat.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de, dave.hansen@linux.intel.com, dzickus@redhat.com To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] x86/nmi: Push duration printk() to irq context Git-Commit-ID: e90c78535283dd0ded3bf2e484890d14dba2d527 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.1 (terminus.zytor.com [127.0.0.1]); Mon, 10 Feb 2014 05:29:23 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: e90c78535283dd0ded3bf2e484890d14dba2d527 Gitweb: http://git.kernel.org/tip/e90c78535283dd0ded3bf2e484890d14dba2d527 Author: Peter Zijlstra AuthorDate: Mon, 3 Feb 2014 18:02:09 +0100 Committer: Ingo Molnar CommitDate: Sun, 9 Feb 2014 13:17:22 +0100 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 Cc: Don Zickus Cc: Dave Hansen Link: http://lkml.kernel.org/n/tip-rdw0au56a5ymis1u8p48c12d@git.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/include/asm/nmi.h | 3 +++ arch/x86/kernel/nmi.c | 37 ++++++++++++++++++++++++------------- 2 files changed, 27 insertions(+), 13 deletions(-) diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h index 86f9301..5f2fc44 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 #include #include #include @@ -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 6fcb49c..b4872b9 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); /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/