From 316c1608d15c736439d4065ed12f306db554b3da Mon Sep 17 00:00:00 2001 From: Jason Low Date: Tue, 28 Apr 2015 13:00:20 -0700 Subject: [PATCH] sched, timer: Convert usages of ACCESS_ONCE() in the scheduler to READ_ONCE()/WRITE_ONCE() ACCESS_ONCE doesn't work reliably on non-scalar types. This patch removes the rest of the existing usages of ACCESS_ONCE() in the scheduler, and use the new READ_ONCE() and WRITE_ONCE() APIs as appropriate. Signed-off-by: Jason Low Signed-off-by: Peter Zijlstra (Intel) Acked-by: Thomas Gleixner Acked-by: Rik van Riel Acked-by: Waiman Long Cc: Andrew Morton Cc: Aswin Chandramouleeswaran Cc: Borislav Petkov Cc: Davidlohr Bueso Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Mel Gorman Cc: Mike Galbraith Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Preeti U Murthy Cc: Scott J Norton Cc: Steven Rostedt Link: http://lkml.kernel.org/r/1430251224-5764-2-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar --- include/linux/sched.h | 4 ++-- kernel/fork.c | 2 +- kernel/sched/auto_group.c | 2 +- kernel/sched/auto_group.h | 2 +- kernel/sched/core.c | 4 ++-- kernel/sched/cputime.c | 2 +- kernel/sched/deadline.c | 2 +- kernel/sched/fair.c | 18 +++++++++--------- kernel/sched/rt.c | 2 +- kernel/sched/sched.h | 2 +- kernel/sched/wait.c | 4 ++-- kernel/time/posix-cpu-timers.c | 8 ++++---- 12 files changed, 26 insertions(+), 26 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index fb650a2f4a73..d70910355b20 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -3085,13 +3085,13 @@ static inline void mm_update_next_owner(struct mm_struct *mm) static inline unsigned long task_rlimit(const struct task_struct *tsk, unsigned int limit) { - return ACCESS_ONCE(tsk->signal->rlim[limit].rlim_cur); + return READ_ONCE(tsk->signal->rlim[limit].rlim_cur); } static inline unsigned long task_rlimit_max(const struct task_struct *tsk, unsigned int limit) { - return ACCESS_ONCE(tsk->signal->rlim[limit].rlim_max); + return READ_ONCE(tsk->signal->rlim[limit].rlim_max); } static inline unsigned long rlimit(unsigned int limit) diff --git a/kernel/fork.c b/kernel/fork.c index 03c1eaaa6ef5..47c37a411a62 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1094,7 +1094,7 @@ static void posix_cpu_timers_init_group(struct signal_struct *sig) /* Thread group counters. */ thread_group_cputime_init(sig); - cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); + cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); if (cpu_limit != RLIM_INFINITY) { sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); sig->cputimer.running = 1; diff --git a/kernel/sched/auto_group.c b/kernel/sched/auto_group.c index 1a3b58d531b2..750ed601ddf7 100644 --- a/kernel/sched/auto_group.c +++ b/kernel/sched/auto_group.c @@ -139,7 +139,7 @@ autogroup_move_group(struct task_struct *p, struct autogroup *ag) p->signal->autogroup = autogroup_kref_get(ag); - if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled)) + if (!READ_ONCE(sysctl_sched_autogroup_enabled)) goto out; for_each_thread(p, t) diff --git a/kernel/sched/auto_group.h b/kernel/sched/auto_group.h index 8bd047142816..890c95f2587a 100644 --- a/kernel/sched/auto_group.h +++ b/kernel/sched/auto_group.h @@ -29,7 +29,7 @@ extern bool task_wants_autogroup(struct task_struct *p, struct task_group *tg); static inline struct task_group * autogroup_task_group(struct task_struct *p, struct task_group *tg) { - int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled); + int enabled = READ_ONCE(sysctl_sched_autogroup_enabled); if (enabled && task_wants_autogroup(p, tg)) return p->signal->autogroup->tg; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 46a5d6f05208..22b53c863ef3 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -511,7 +511,7 @@ static bool set_nr_and_not_polling(struct task_struct *p) static bool set_nr_if_polling(struct task_struct *p) { struct thread_info *ti = task_thread_info(p); - typeof(ti->flags) old, val = ACCESS_ONCE(ti->flags); + typeof(ti->flags) old, val = READ_ONCE(ti->flags); for (;;) { if (!(val & _TIF_POLLING_NRFLAG)) @@ -2526,7 +2526,7 @@ void scheduler_tick(void) u64 scheduler_tick_max_deferment(void) { struct rq *rq = this_rq(); - unsigned long next, now = ACCESS_ONCE(jiffies); + unsigned long next, now = READ_ONCE(jiffies); next = rq->last_sched_tick + HZ; diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 8394b1ee600c..f5a64ffad176 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -567,7 +567,7 @@ static void cputime_advance(cputime_t *counter, cputime_t new) { cputime_t old; - while (new > (old = ACCESS_ONCE(*counter))) + while (new > (old = READ_ONCE(*counter))) cmpxchg_cputime(counter, old, new); } diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 5e95145088fd..890ce951c717 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -995,7 +995,7 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) rq = cpu_rq(cpu); rcu_read_lock(); - curr = ACCESS_ONCE(rq->curr); /* unlocked access */ + curr = READ_ONCE(rq->curr); /* unlocked access */ /* * If we are dealing with a -deadline task, we must diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4bc6013886ec..d6915a038d8a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -834,7 +834,7 @@ static unsigned int task_nr_scan_windows(struct task_struct *p) static unsigned int task_scan_min(struct task_struct *p) { - unsigned int scan_size = ACCESS_ONCE(sysctl_numa_balancing_scan_size); + unsigned int scan_size = READ_ONCE(sysctl_numa_balancing_scan_size); unsigned int scan, floor; unsigned int windows = 1; @@ -1794,7 +1794,7 @@ static void task_numa_placement(struct task_struct *p) u64 runtime, period; spinlock_t *group_lock = NULL; - seq = ACCESS_ONCE(p->mm->numa_scan_seq); + seq = READ_ONCE(p->mm->numa_scan_seq); if (p->numa_scan_seq == seq) return; p->numa_scan_seq = seq; @@ -1938,7 +1938,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags, } rcu_read_lock(); - tsk = ACCESS_ONCE(cpu_rq(cpu)->curr); + tsk = READ_ONCE(cpu_rq(cpu)->curr); if (!cpupid_match_pid(tsk, cpupid)) goto no_join; @@ -2107,7 +2107,7 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) static void reset_ptenuma_scan(struct task_struct *p) { - ACCESS_ONCE(p->mm->numa_scan_seq)++; + WRITE_ONCE(p->mm->numa_scan_seq, READ_ONCE(p->mm->numa_scan_seq) + 1); p->mm->numa_scan_offset = 0; } @@ -4451,7 +4451,7 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load, */ static void update_idle_cpu_load(struct rq *this_rq) { - unsigned long curr_jiffies = ACCESS_ONCE(jiffies); + unsigned long curr_jiffies = READ_ONCE(jiffies); unsigned long load = this_rq->cfs.runnable_load_avg; unsigned long pending_updates; @@ -4473,7 +4473,7 @@ static void update_idle_cpu_load(struct rq *this_rq) void update_cpu_load_nohz(void) { struct rq *this_rq = this_rq(); - unsigned long curr_jiffies = ACCESS_ONCE(jiffies); + unsigned long curr_jiffies = READ_ONCE(jiffies); unsigned long pending_updates; if (curr_jiffies == this_rq->last_load_update_tick) @@ -4558,7 +4558,7 @@ static unsigned long capacity_orig_of(int cpu) static unsigned long cpu_avg_load_per_task(int cpu) { struct rq *rq = cpu_rq(cpu); - unsigned long nr_running = ACCESS_ONCE(rq->cfs.h_nr_running); + unsigned long nr_running = READ_ONCE(rq->cfs.h_nr_running); unsigned long load_avg = rq->cfs.runnable_load_avg; if (nr_running) @@ -6220,8 +6220,8 @@ static unsigned long scale_rt_capacity(int cpu) * Since we're reading these variables without serialization make sure * we read them once before doing sanity checks on them. */ - age_stamp = ACCESS_ONCE(rq->age_stamp); - avg = ACCESS_ONCE(rq->rt_avg); + age_stamp = READ_ONCE(rq->age_stamp); + avg = READ_ONCE(rq->rt_avg); delta = __rq_clock_broken(rq) - age_stamp; if (unlikely(delta < 0)) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 575da76a3874..560d2fa623c3 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1323,7 +1323,7 @@ select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags) rq = cpu_rq(cpu); rcu_read_lock(); - curr = ACCESS_ONCE(rq->curr); /* unlocked access */ + curr = READ_ONCE(rq->curr); /* unlocked access */ /* * If the current task on @p's runqueue is an RT task, then diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 09ed26a89f31..d85455539d5c 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -713,7 +713,7 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); static inline u64 __rq_clock_broken(struct rq *rq) { - return ACCESS_ONCE(rq->clock); + return READ_ONCE(rq->clock); } static inline u64 rq_clock(struct rq *rq) diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c index 852143a79f36..2ccec988d6b7 100644 --- a/kernel/sched/wait.c +++ b/kernel/sched/wait.c @@ -601,7 +601,7 @@ EXPORT_SYMBOL(bit_wait_io); __sched int bit_wait_timeout(struct wait_bit_key *word) { - unsigned long now = ACCESS_ONCE(jiffies); + unsigned long now = READ_ONCE(jiffies); if (signal_pending_state(current->state, current)) return 1; if (time_after_eq(now, word->timeout)) @@ -613,7 +613,7 @@ EXPORT_SYMBOL_GPL(bit_wait_timeout); __sched int bit_wait_io_timeout(struct wait_bit_key *word) { - unsigned long now = ACCESS_ONCE(jiffies); + unsigned long now = READ_ONCE(jiffies); if (signal_pending_state(current->state, current)) return 1; if (time_after_eq(now, word->timeout)) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 0075da74abf0..e072d982f64c 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -852,10 +852,10 @@ static void check_thread_timers(struct task_struct *tsk, /* * Check for the special case thread timers. */ - soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur); + soft = READ_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur); if (soft != RLIM_INFINITY) { unsigned long hard = - ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max); + READ_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max); if (hard != RLIM_INFINITY && tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) { @@ -958,11 +958,11 @@ static void check_process_timers(struct task_struct *tsk, SIGPROF); check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime, SIGVTALRM); - soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); + soft = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); if (soft != RLIM_INFINITY) { unsigned long psecs = cputime_to_secs(ptime); unsigned long hard = - ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max); + READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_max); cputime_t x; if (psecs >= hard) { /*