Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 316c1608 authored by Jason Low's avatar Jason Low Committed by Ingo Molnar
Browse files

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: default avatarJason Low <jason.low2@hp.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarWaiman Long <Waiman.Long@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1430251224-5764-2-git-send-email-jason.low2@hp.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent ce2f5fe4

include/linux/sched.h

+2 −2
Original line number Diff line number Diff line
@@ -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)

kernel/fork.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

kernel/sched/auto_group.c

+1 −1
Original line number Diff line number Diff line
@@ -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)

kernel/sched/auto_group.h

+1 −1
Original line number Diff line number Diff line
@@ -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;

kernel/sched/core.c

+2 −2
Original line number Diff line number Diff line
@@ -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;