Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161941Ab3DEIrl (ORCPT ); Fri, 5 Apr 2013 04:47:41 -0400 Received: from mail-ve0-f181.google.com ([209.85.128.181]:40504 "EHLO mail-ve0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751127Ab3DEIrb (ORCPT ); Fri, 5 Apr 2013 04:47:31 -0400 From: kosaki.motohiro@gmail.com To: linux-kernel@vger.kernel.org Cc: KOSAKI Motohiro , Peter Zijlstra , David Miller , stable@kernel.org, Thomas Gleixner , Frederic Weisbecker Subject: [PATCH] posix-cpu-timers: fix counting delta_exec twice Date: Sat, 6 Apr 2013 11:47:08 -0400 Message-Id: <1365263228-9373-1-git-send-email-kosaki.motohiro@gmail.com> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7395 Lines: 199 From: KOSAKI Motohiro Currently glibc rt/cpuclock2 test(*) sporadically fail. The pseudo test code is here. t0 = clock_gettime() abs = t0 + sleeptime; clock_nanosleep(TIMER_ABSTIME, abs) t1 = clock_gettime() assert(t1-t0 > sleeptime) assert(t1 > abs) Because current signal->cputimer->cputime logic can add delta_exec twice wrongly. The first is in initialization, thread_group_cputimer() call thread_group_cputime() and it adds delta_exec. and later, update_curr() adds delta_exec again. Finally, clock_nanosleep() wakes up slightly before than passed argument and it is posix violation. This issue was introduced by commit d670ec1317 (posix-cpu-timers: Cure SMP wobbles). (*) http://sourceware.org/git/?p=glibc.git;a=blob;f=rt/tst-cpuclock2.c;h=6752721717f959e89c0d692b3f1ee082d507eec2;hb=HEAD Cc: Peter Zijlstra Cc: David Miller Cc: stable@kernel.org Cc: Thomas Gleixner Cc: Frederic Weisbecker Signed-off-by: KOSAKI Motohiro --- fs/binfmt_elf.c | 2 +- fs/binfmt_elf_fdpic.c | 2 +- include/linux/sched.h | 4 ++-- kernel/posix-cpu-timers.c | 10 +++++----- kernel/sched/core.c | 6 ++++-- kernel/sched/cputime.c | 8 ++++---- 6 files changed, 17 insertions(+), 15 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 3939829..e139e18 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1321,7 +1321,7 @@ static void fill_prstatus(struct elf_prstatus *prstatus, * This is the record for the group leader. It shows the * group-wide total, not its individual thread total. */ - thread_group_cputime(p, &cputime); + thread_group_cputime(p, true, &cputime); cputime_to_timeval(cputime.utime, &prstatus->pr_utime); cputime_to_timeval(cputime.stime, &prstatus->pr_stime); } else { diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 9c13e02..ab5b508 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -1371,7 +1371,7 @@ static void fill_prstatus(struct elf_prstatus *prstatus, * This is the record for the group leader. It shows the * group-wide total, not its individual thread total. */ - thread_group_cputime(p, &cputime); + thread_group_cputime(p, true, &cputime); cputime_to_timeval(cputime.utime, &prstatus->pr_utime); cputime_to_timeval(cputime.stime, &prstatus->pr_stime); } else { diff --git a/include/linux/sched.h b/include/linux/sched.h index d35d2b6..deb49f3 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2001,7 +2001,7 @@ static inline void disable_sched_clock_irqtime(void) {} #endif extern unsigned long long -task_sched_runtime(struct task_struct *task); +task_sched_runtime(struct task_struct *task, bool use_delta); /* sched_exec is called by processes performing an exec */ #ifdef CONFIG_SMP @@ -2624,7 +2624,7 @@ static inline int spin_needbreak(spinlock_t *lock) /* * Thread group CPU time accounting. */ -void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times); +void thread_group_cputime(struct task_struct *tsk, bool use_delta, struct task_cputime *times); void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times); static inline void thread_group_cputime_init(struct signal_struct *sig) diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index 8fd709c..948004d 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -220,7 +220,7 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p, cpu->cpu = virt_ticks(p); break; case CPUCLOCK_SCHED: - cpu->sched = task_sched_runtime(p); + cpu->sched = task_sched_runtime(p, true); break; } return 0; @@ -251,7 +251,7 @@ void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) * to synchronize the timer to the clock every time we start * it. */ - thread_group_cputime(tsk, &sum); + thread_group_cputime(tsk, false, &sum); raw_spin_lock_irqsave(&cputimer->lock, flags); cputimer->running = 1; update_gt_cputime(&cputimer->cputime, &sum); @@ -275,15 +275,15 @@ static int cpu_clock_sample_group(const clockid_t which_clock, default: return -EINVAL; case CPUCLOCK_PROF: - thread_group_cputime(p, &cputime); + thread_group_cputime(p, true, &cputime); cpu->cpu = cputime.utime + cputime.stime; break; case CPUCLOCK_VIRT: - thread_group_cputime(p, &cputime); + thread_group_cputime(p, true, &cputime); cpu->cpu = cputime.utime; break; case CPUCLOCK_SCHED: - thread_group_cputime(p, &cputime); + thread_group_cputime(p, true, &cputime); cpu->sched = cputime.sum_exec_runtime; break; } diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7f12624..b2c78e1 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2662,14 +2662,16 @@ unsigned long long task_delta_exec(struct task_struct *p) * In case the task is currently running, return the runtime plus current's * pending runtime that have not been accounted yet. */ -unsigned long long task_sched_runtime(struct task_struct *p) +unsigned long long task_sched_runtime(struct task_struct *p, bool use_delta) { unsigned long flags; struct rq *rq; u64 ns = 0; rq = task_rq_lock(p, &flags); - ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq); + ns = p->se.sum_exec_runtime; + if (use_delta) + ns += do_task_delta_exec(p, rq); task_rq_unlock(rq, p, &flags); return ns; diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index e93cca9..ee72d31 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -293,7 +293,7 @@ static __always_inline bool steal_account_process_tick(void) * Accumulate raw cputime values of dead tasks (sig->[us]time) and live * tasks (sum on group iteration) belonging to @tsk's group. */ -void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times) +void thread_group_cputime(struct task_struct *tsk, bool use_delta, struct task_cputime *times) { struct signal_struct *sig = tsk->signal; cputime_t utime, stime; @@ -313,7 +313,7 @@ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times) task_cputime(t, &utime, &stime); times->utime += utime; times->stime += stime; - times->sum_exec_runtime += task_sched_runtime(t); + times->sum_exec_runtime += task_sched_runtime(t, use_delta); } while_each_thread(tsk, t); out: rcu_read_unlock(); @@ -459,7 +459,7 @@ void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime { struct task_cputime cputime; - thread_group_cputime(p, &cputime); + thread_group_cputime(p, true, &cputime); *ut = cputime.utime; *st = cputime.stime; @@ -594,7 +594,7 @@ void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime { struct task_cputime cputime; - thread_group_cputime(p, &cputime); + thread_group_cputime(p, true, &cputime); cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st); } #endif /* !CONFIG_VIRT_CPU_ACCOUNTING */ -- 1.7.1 -- 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/