From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82593C3A59E for ; Wed, 21 Aug 2019 19:31:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5B64B2064A for ; Wed, 21 Aug 2019 19:31:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730146AbfHUTbD (ORCPT ); Wed, 21 Aug 2019 15:31:03 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:57258 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730048AbfHUTbA (ORCPT ); Wed, 21 Aug 2019 15:31:00 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1i0WJt-0004Dg-RE; Wed, 21 Aug 2019 21:30:57 +0200 Message-Id: <20190821192921.105793824@linutronix.de> User-Agent: quilt/0.65 Date: Wed, 21 Aug 2019 21:09:07 +0200 From: Thomas Gleixner To: LKML Cc: Oleg Nesterov , Ingo Molnar , Peter Zijlstra , John Stultz , Frederic Weisbecker , Anna-Maria Behnsen , Christoph Hellwig Subject: [patch V2 20/38] posix-cpu-timers: Provide array based access to expiry cache References: <20190821190847.665673890@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using struct task_cputime for the expiry cache is a pretty odd choice and comes with magic defines to rename the fields for usage in the expiry cache. struct task_cputime is basically a u64 array with 3 members, but it has distinct members. The expiry cache content is different than the content of task_cputime because expiry[PROF] = task_cputime.stime + task_cputime.utime expiry[VIRT] = task_cputime.utime expiry[SCHED] = task_cputime.sum_exec_runtime So there is no direct mapping between task_cputime and the expiry cache and the #define based remapping is just a horrible hack. Having the expiry cache array based allows further simplification of the expiry code. To avoid an all in one cleanup which is hard to review add a temporary anonymous union into struct task_cputime which allows array based access to it. That requires to reorder the members. Add a build time sanity check to validate that the members are at the same place. The union and the build time checks will be removed after conversion. Signed-off-by: Thomas Gleixner --- include/linux/posix-timers.h | 24 ++++++++++++++++++------ include/linux/sched/types.h | 4 ++-- kernel/time/posix-cpu-timers.c | 12 +++++++++++- 3 files changed, 31 insertions(+), 9 deletions(-) --- a/include/linux/posix-timers.h +++ b/include/linux/posix-timers.h @@ -65,27 +65,39 @@ static inline int clockid_to_fd(const cl /* * Alternate field names for struct task_cputime when used on cache * expirations. Will go away soon. + * + * stime corresponds to CLOCKCPU_PROF + * utime corresponds to CLOCKCPU_VIRT + * sum_exex_runtime corresponds to CLOCKCPU_SCHED + * + * The ordering is currently enforced so struct task_cputime and the + * expiries array in struct posix_cputimers are equivalent. */ -#define virt_exp utime #define prof_exp stime +#define virt_exp utime #define sched_exp sum_exec_runtime #ifdef CONFIG_POSIX_TIMERS /** * posix_cputimers - Container for posix CPU timer related data - * @cputime_expires: Earliest-expiration cache + * @cputime_expires: Earliest-expiration cache task_cputime based + * @expiries: Earliest-expiration cache array based * @cpu_timers: List heads to queue posix CPU timers * * Used in task_struct and signal_struct */ struct posix_cputimers { - struct task_cputime cputime_expires; - struct list_head cpu_timers[CPUCLOCK_MAX]; + /* Temporary union until all users are cleaned up */ + union { + struct task_cputime cputime_expires; + u64 expiries[CPUCLOCK_MAX]; + }; + struct list_head cpu_timers[CPUCLOCK_MAX]; }; static inline void posix_cputimers_init(struct posix_cputimers *pct) { - memset(&pct->cputime_expires, 0, sizeof(pct->cputime_expires)); + memset(&pct->expiries, 0, sizeof(pct->expiries)); INIT_LIST_HEAD(&pct->cpu_timers[0]); INIT_LIST_HEAD(&pct->cpu_timers[1]); INIT_LIST_HEAD(&pct->cpu_timers[2]); @@ -96,7 +108,7 @@ void posix_cputimers_group_init(struct p static inline void posix_cputimers_rt_watchdog(struct posix_cputimers *pct, u64 runtime) { - pct->cputime_expires.sched_exp = runtime; + pct->expiries[CPUCLOCK_SCHED] = runtime; } /* Init task static initializer */ --- a/include/linux/sched/types.h +++ b/include/linux/sched/types.h @@ -6,8 +6,8 @@ /** * struct task_cputime - collected CPU time counts - * @utime: time spent in user mode, in nanoseconds * @stime: time spent in kernel mode, in nanoseconds + * @utime: time spent in user mode, in nanoseconds * @sum_exec_runtime: total time spent on the CPU, in nanoseconds * * This structure groups together three kinds of CPU time that are tracked for @@ -15,8 +15,8 @@ * these counts together and treat all three of them in parallel. */ struct task_cputime { - u64 utime; u64 stime; + u64 utime; unsigned long long sum_exec_runtime; }; --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -18,13 +18,23 @@ #include "posix-timers.h" +static inline void temporary_check(void) +{ + BUILD_BUG_ON(offsetof(struct task_cputime, stime) != + CPUCLOCK_PROF * sizeof(u64)); + BUILD_BUG_ON(offsetof(struct task_cputime, utime) != + CPUCLOCK_VIRT * sizeof(u64)); + BUILD_BUG_ON(offsetof(struct task_cputime, sum_exec_runtime) != + CPUCLOCK_SCHED * sizeof(u64)); +} + static void posix_cpu_timer_rearm(struct k_itimer *timer); void posix_cputimers_group_init(struct posix_cputimers *pct, u64 cpu_limit) { posix_cputimers_init(pct); if (cpu_limit != RLIM_INFINITY) - pct->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC; + pct->expiries[CPUCLOCK_PROF] = cpu_limit * NSEC_PER_SEC; } /*