From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:41685 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752333AbcIIQHE (ORCPT ); Fri, 9 Sep 2016 12:07:04 -0400 Subject: Patch "timekeeping: Avoid taking lock in NMI path with CONFIG_DEBUG_TIMEKEEPING" has been added to the 4.4-stable tree To: john.stultz@linaro.org, gregkh@linuxfoundation.org, peterz@infradead.org, rostedt@goodmis.org, tglx@linutronix.de Cc: , From: Date: Fri, 09 Sep 2016 18:06:58 +0200 Message-ID: <147343721866111@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled timekeeping: Avoid taking lock in NMI path with CONFIG_DEBUG_TIMEKEEPING to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: timekeeping-avoid-taking-lock-in-nmi-path-with-config_debug_timekeeping.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 27727df240c7cc84f2ba6047c6f18d5addfd25ef Mon Sep 17 00:00:00 2001 From: John Stultz Date: Tue, 23 Aug 2016 16:08:21 -0700 Subject: timekeeping: Avoid taking lock in NMI path with CONFIG_DEBUG_TIMEKEEPING From: John Stultz commit 27727df240c7cc84f2ba6047c6f18d5addfd25ef upstream. When I added some extra sanity checking in timekeeping_get_ns() under CONFIG_DEBUG_TIMEKEEPING, I missed that the NMI safe __ktime_get_fast_ns() method was using timekeeping_get_ns(). Thus the locking added to the debug checks broke the NMI-safety of __ktime_get_fast_ns(). This patch open-codes the timekeeping_get_ns() logic for __ktime_get_fast_ns(), so can avoid any deadlocks in NMI. Fixes: 4ca22c2648f9 "timekeeping: Add warnings when overflows or underflows are observed" Reported-by: Steven Rostedt Reported-by: Peter Zijlstra Signed-off-by: John Stultz Link: http://lkml.kernel.org/r/1471993702-29148-2-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- kernel/time/timekeeping.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -383,7 +383,10 @@ static __always_inline u64 __ktime_get_f do { seq = raw_read_seqcount_latch(&tkf->seq); tkr = tkf->base + (seq & 0x01); - now = ktime_to_ns(tkr->base) + timekeeping_get_ns(tkr); + now = ktime_to_ns(tkr->base); + + now += clocksource_delta(tkr->read(tkr->clock), + tkr->cycle_last, tkr->mask); } while (read_seqcount_retry(&tkf->seq, seq)); return now; Patches currently in stable-queue which might be from john.stultz@linaro.org are queue-4.4/0110-ntp-Fix-ADJ_SETOFFSET-being-used-w-ADJ_NANO.patch queue-4.4/timekeeping-avoid-taking-lock-in-nmi-path-with-config_debug_timekeeping.patch queue-4.4/0109-time-Verify-time-values-in-adjtimex-ADJ_SETOFFSET-to.patch queue-4.4/0118-clocksource-Allow-unregistering-the-watchdog.patch queue-4.4/timekeeping-cap-array-access-in-timekeeping_debug.patch