From patchwork Thu Jul 5 19:12:18 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: john stultz X-Patchwork-Id: 9865 Return-Path: X-Original-To: patchwork@peony.canonical.com Delivered-To: patchwork@peony.canonical.com Received: from fiordland.canonical.com (fiordland.canonical.com [91.189.94.145]) by peony.canonical.com (Postfix) with ESMTP id 1948623E4F for ; Thu, 5 Jul 2012 19:14:13 +0000 (UTC) Received: from mail-yx0-f180.google.com (mail-yx0-f180.google.com [209.85.213.180]) by fiordland.canonical.com (Postfix) with ESMTP id C57CBA18450 for ; Thu, 5 Jul 2012 19:14:12 +0000 (UTC) Received: by yenq6 with SMTP id q6so8418139yen.11 for ; Thu, 05 Jul 2012 12:14:12 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-forwarded-to:x-forwarded-for:delivered-to:received-spf:from:to:cc :subject:date:message-id:x-mailer:in-reply-to:references :x-content-scanned:x-cbid:x-gm-message-state; bh=/wXVII8oNLcl6nKnZcfOzclZt/rHSz6XgI4cg+UUj6c=; b=AXLq3WEKFr90Fk22FeSPbjgxMcXH0Ui5Kda9yYc7S6p4yu/UMmSQl3iyh2lGXNXLqr dUP0AT24oxex+cU7LNEpB5HFYQ7zAyZyJDGMXGRPQ5EFKXwlv/x1zn9vNfnr7JyghK4A 8hd+Lz491D1VXacn0zlzJoHImK1nGD8tSwyD7Zx2HqLqPulup+SGz4pGbNV1GahH14rC S21FXUqs3JR9vX3vz2+ymBFLooYRjBSIdGBYjB6Z8XmDfX2vMzpRt/szJl1EPEIWlgNZ LajMmrVZ8RAK3iIoIeYw2vN0NOUNAIA3KoXKhY49e5KEi0KCCbzXd0lxNNXgNo/iej2X UVLA== Received: by 10.50.203.39 with SMTP id kn7mr606188igc.53.1341515651999; Thu, 05 Jul 2012 12:14:11 -0700 (PDT) X-Forwarded-To: linaro-patchwork@canonical.com X-Forwarded-For: patch@linaro.org linaro-patchwork@canonical.com Delivered-To: patches@linaro.org Received: by 10.231.24.148 with SMTP id v20csp211ibb; Thu, 5 Jul 2012 12:14:11 -0700 (PDT) Received: by 10.68.194.169 with SMTP id hx9mr30068839pbc.8.1341515651286; Thu, 05 Jul 2012 12:14:11 -0700 (PDT) Received: from e35.co.us.ibm.com (e35.co.us.ibm.com. 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Violators will be prosecuted; Thu, 5 Jul 2012 13:13:31 -0600 Received: from d03relay01.boulder.ibm.com (d03relay01.boulder.ibm.com [9.17.195.226]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 6706C19D8051 for ; Thu, 5 Jul 2012 19:13:30 +0000 (WET) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay01.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q65JDJTH172900 for ; Thu, 5 Jul 2012 13:13:20 -0600 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q65JDHCk007722 for ; Thu, 5 Jul 2012 13:13:18 -0600 Received: from kernel.stglabs.ibm.com (kernel.stglabs.ibm.com [9.114.214.19]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q65JD4xP006244; Thu, 5 Jul 2012 13:13:13 -0600 From: John Stultz To: Linux Kernel Cc: John Stultz , Prarit Bhargava , stable@vger.kernel.org, Thomas Gleixner Subject: [PATCH 3/3] hrtimer: Update hrtimer base offsets each hrtimer_interrupt Date: Thu, 5 Jul 2012 15:12:18 -0400 Message-Id: <1341515538-5100-4-git-send-email-johnstul@us.ibm.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1341515538-5100-1-git-send-email-johnstul@us.ibm.com> References: <1341515538-5100-1-git-send-email-johnstul@us.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12070519-6148-0000-0000-00000763B286 X-Gm-Message-State: ALoCoQm3fUWZQpg8KmUlU6IY3bNi73v7trnjb2PTXfcQRq95gCEPTPVO8tIyHvtHJeeQit9UWF44 This patch introduces a new funciton which captures the CLOCK_MONOTONIC time, along with the CLOCK_REALTIME and CLOCK_BOOTTIME offsets at the same moment. This new function is then used in place of ktime_get() when hrtimer_interrupt() is expiring timers. This ensures that any changes to realtime or boottime offsets are noticed and stored into the per-cpu hrtimer base structures, prior to doing any hrtimer expiration. This should ensure that timers are not expired early if the offsets changes under us. This is useful in the case where clock_was_set() is called from atomic context and have to schedule the hrtimer base offset update via a timer, as it provides extra robustness in the face of any possible timer delay. CC: Prarit Bhargava CC: stable@vger.kernel.org CC: Thomas Gleixner Acked-by: Prarit Bhargava Signed-off-by: John Stultz --- include/linux/hrtimer.h | 3 +++ kernel/hrtimer.c | 14 +++++++++++--- kernel/time/timekeeping.c | 34 ++++++++++++++++++++++++++++++++++ 3 files changed, 48 insertions(+), 3 deletions(-) diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index fd0dc30..f6b2a74 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -320,6 +320,9 @@ extern ktime_t ktime_get(void); extern ktime_t ktime_get_real(void); extern ktime_t ktime_get_boottime(void); extern ktime_t ktime_get_monotonic_offset(void); +extern void ktime_get_and_real_and_sleep_offset(ktime_t *monotonic, + ktime_t *real_offset, + ktime_t *sleep_offset); DECLARE_PER_CPU(struct tick_device, tick_cpu_device); diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index d730678..56600c4 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1258,18 +1258,26 @@ static void __run_hrtimer(struct hrtimer *timer, ktime_t *now) void hrtimer_interrupt(struct clock_event_device *dev) { struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); - ktime_t expires_next, now, entry_time, delta; + ktime_t expires_next, now, entry_time, delta, real_offset, sleep_offset; int i, retries = 0; BUG_ON(!cpu_base->hres_active); cpu_base->nr_events++; dev->next_event.tv64 = KTIME_MAX; - entry_time = now = ktime_get(); + + ktime_get_and_real_and_sleep_offset(&now, &real_offset, &sleep_offset); + + entry_time = now; retry: expires_next.tv64 = KTIME_MAX; raw_spin_lock(&cpu_base->lock); + + /* Update base offsets, to avoid early wakeups */ + cpu_base->clock_base[HRTIMER_BASE_REALTIME].offset = real_offset; + cpu_base->clock_base[HRTIMER_BASE_BOOTTIME].offset = sleep_offset; + /* * We set expires_next to KTIME_MAX here with cpu_base->lock * held to prevent that a timer is enqueued in our queue via @@ -1346,7 +1354,7 @@ retry: * interrupt routine. We give it 3 attempts to avoid * overreacting on some spurious event. */ - now = ktime_get(); + ktime_get_and_real_and_sleep_offset(&now, &real_offset, &sleep_offset); cpu_base->nr_retries++; if (++retries < 3) goto retry; diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index cc2991d..b3404cf 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1251,6 +1251,40 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim, } /** + * ktime_get_and_real_and_sleep_offset() - hrtimer helper, gets monotonic ktime, + * realtime offset, and sleep offsets. + */ +void ktime_get_and_real_and_sleep_offset(ktime_t *monotonic, + ktime_t *real_offset, + ktime_t *sleep_offset) +{ + unsigned long seq; + struct timespec wtom, sleep; + u64 secs, nsecs; + + do { + seq = read_seqbegin(&timekeeper.lock); + + secs = timekeeper.xtime.tv_sec + + timekeeper.wall_to_monotonic.tv_sec; + nsecs = timekeeper.xtime.tv_nsec + + timekeeper.wall_to_monotonic.tv_nsec; + nsecs += timekeeping_get_ns(); + /* If arch requires, add in gettimeoffset() */ + nsecs += arch_gettimeoffset(); + + wtom = timekeeper.wall_to_monotonic; + sleep = timekeeper.total_sleep_time; + } while (read_seqretry(&timekeeper.lock, seq)); + + *monotonic = ktime_add_ns(ktime_set(secs, 0), nsecs); + set_normalized_timespec(&wtom, -wtom.tv_sec, -wtom.tv_nsec); + *real_offset = timespec_to_ktime(wtom); + *sleep_offset = timespec_to_ktime(sleep); +} + + +/** * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format */ ktime_t ktime_get_monotonic_offset(void)