timers: Omit POSIX timer stuff from task_struct when disabled

When CONFIG_POSIX_TIMERS is disabled, it is preferable to remove related
structures from struct task_struct and struct signal_struct as they
won't contain anything useful and shouldn't be relied upon by mistake.
Code still referencing those structures is also disabled here.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8e7e61b..03deeac 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2179,7 +2179,7 @@ static const struct file_operations proc_map_files_operations = {
        .llseek         = generic_file_llseek,
 };
 
-#ifdef CONFIG_CHECKPOINT_RESTORE
+#if defined(CONFIG_CHECKPOINT_RESTORE) && defined(CONFIG_POSIX_TIMERS)
 struct timers_private {
        struct pid *pid;
        struct task_struct *task;
@@ -2936,7 +2936,7 @@ static const struct pid_entry tgid_base_stuff[] = {
        REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
        REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
 #endif
-#ifdef CONFIG_CHECKPOINT_RESTORE
+#if defined(CONFIG_CHECKPOINT_RESTORE) && defined(CONFIG_POSIX_TIMERS)
        REG("timers",     S_IRUGO, proc_timers_operations),
 #endif
        REG("timerslack_ns", S_IRUGO|S_IWUGO, proc_pid_set_timerslack_ns_operations),

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 325f649..3a85d61 100644 (file)
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -42,6 +42,27 @@ extern struct fs_struct init_fs;
 #define INIT_PREV_CPUTIME(x)
 #endif
 
+#ifdef CONFIG_POSIX_TIMERS
+#define INIT_POSIX_TIMERS(s)                                           \
+       .posix_timers = LIST_HEAD_INIT(s.posix_timers),
+#define INIT_CPU_TIMERS(s)                                             \
+       .cpu_timers = {                                                 \
+               LIST_HEAD_INIT(s.cpu_timers[0]),                        \
+               LIST_HEAD_INIT(s.cpu_timers[1]),                        \
+               LIST_HEAD_INIT(s.cpu_timers[2]),                                                                \
+       },
+#define INIT_CPUTIMER(s)                                               \
+       .cputimer       = {                                             \
+               .cputime_atomic = INIT_CPUTIME_ATOMIC,                  \
+               .running        = false,                                \
+               .checking_timer = false,                                \
+       },
+#else
+#define INIT_POSIX_TIMERS(s)
+#define INIT_CPU_TIMERS(s)
+#define INIT_CPUTIMER(s)
+#endif
+
 #define INIT_SIGNALS(sig) {                                            \
        .nr_threads     = 1,                                            \
        .thread_head    = LIST_HEAD_INIT(init_task.thread_node),        \
@@ -49,14 +70,10 @@ extern struct fs_struct init_fs;
        .shared_pending = {                                             \
                .list = LIST_HEAD_INIT(sig.shared_pending.list),        \
                .signal =  {{0}}},                                      \
-       .posix_timers    = LIST_HEAD_INIT(sig.posix_timers),            \
-       .cpu_timers     = INIT_CPU_TIMERS(sig.cpu_timers),              \
+       INIT_POSIX_TIMERS(sig)                                          \
+       INIT_CPU_TIMERS(sig)                                            \
        .rlim           = INIT_RLIMITS,                                 \
-       .cputimer       = {                                             \
-               .cputime_atomic = INIT_CPUTIME_ATOMIC,                  \
-               .running        = false,                                \
-               .checking_timer = false,                                \
-       },                                                              \
+       INIT_CPUTIMER(sig)                                              \
        INIT_PREV_CPUTIME(sig)                                          \
        .cred_guard_mutex =                                             \
                 __MUTEX_INITIALIZER(sig.cred_guard_mutex),             \
@@ -247,7 +264,7 @@ extern struct task_group root_task_group;
        .blocked        = {{0}},                                        \
        .alloc_lock     = __SPIN_LOCK_UNLOCKED(tsk.alloc_lock),         \
        .journal_info   = NULL,                                         \
-       .cpu_timers     = INIT_CPU_TIMERS(tsk.cpu_timers),              \
+       INIT_CPU_TIMERS(tsk)                                            \
        .pi_lock        = __RAW_SPIN_LOCK_UNLOCKED(tsk.pi_lock),        \
        .timer_slack_ns = 50000, /* 50 usec default slack */            \
        .pids = {                                                       \
@@ -274,13 +291,6 @@ extern struct task_group root_task_group;
 }
 
 
-#define INIT_CPU_TIMERS(cpu_timers)                                    \
-{                                                                      \
-       LIST_HEAD_INIT(cpu_timers[0]),                                  \
-       LIST_HEAD_INIT(cpu_timers[1]),                                  \
-       LIST_HEAD_INIT(cpu_timers[2]),                                  \
-}
-
 /* Attach to the init_task data structure for proper alignment */
 #define __init_task_data __attribute__((__section__(".data..init_task")))
 

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4d19052..e8f6af5 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -734,13 +734,14 @@ struct signal_struct {
        unsigned int            is_child_subreaper:1;
        unsigned int            has_child_subreaper:1;
 
+#ifdef CONFIG_POSIX_TIMERS
+
        /* POSIX.1b Interval Timers */
        int                     posix_timer_id;
        struct list_head        posix_timers;
 
        /* ITIMER_REAL timer for the process */
        struct hrtimer real_timer;
-       struct pid *leader_pid;
        ktime_t it_real_incr;
 
        /*
@@ -759,12 +760,16 @@ struct signal_struct {
        /* Earliest-expiration cache. */
        struct task_cputime cputime_expires;
 
+       struct list_head cpu_timers[3];
+
+#endif
+
+       struct pid *leader_pid;
+
 #ifdef CONFIG_NO_HZ_FULL
        atomic_t tick_dep_mask;
 #endif
 
-       struct list_head cpu_timers[3];
-
        struct pid *tty_old_pgrp;
 
        /* boolean value for session group leader */
@@ -1681,8 +1686,10 @@ struct task_struct {
 /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
        unsigned long min_flt, maj_flt;
 
+#ifdef CONFIG_POSIX_TIMERS
        struct task_cputime cputime_expires;
        struct list_head cpu_timers[3];
+#endif
 
 /* process credentials */
        const struct cred __rcu *ptracer_cred; /* Tracer's credentials at attach */

diff --git a/kernel/fork.c b/kernel/fork.c
index 11c5c8a..105c667 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1304,6 +1304,7 @@ void __cleanup_sighand(struct sighand_struct *sighand)
        }
 }
 
+#ifdef CONFIG_POSIX_TIMERS
 /*
  * Initialize POSIX timer handling for a thread group.
  */
@@ -1322,6 +1323,9 @@ static void posix_cpu_timers_init_group(struct signal_struct *sig)
        INIT_LIST_HEAD(&sig->cpu_timers[1]);
        INIT_LIST_HEAD(&sig->cpu_timers[2]);
 }
+#else
+static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { }
+#endif
 
 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
 {
@@ -1346,11 +1350,11 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
        init_waitqueue_head(&sig->wait_chldexit);
        sig->curr_target = tsk;
        init_sigpending(&sig->shared_pending);
-       INIT_LIST_HEAD(&sig->posix_timers);
        seqlock_init(&sig->stats_lock);
        prev_cputime_init(&sig->prev_cputime);
 
 #ifdef CONFIG_POSIX_TIMERS
+       INIT_LIST_HEAD(&sig->posix_timers);
        hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
        sig->real_timer.function = it_real_fn;
 #endif
@@ -1425,6 +1429,7 @@ static void rt_mutex_init_task(struct task_struct *p)
 #endif
 }
 
+#ifdef CONFIG_POSIX_TIMERS
 /*
  * Initialize POSIX timer handling for a single task.
  */
@@ -1437,6 +1442,9 @@ static void posix_cpu_timers_init(struct task_struct *tsk)
        INIT_LIST_HEAD(&tsk->cpu_timers[1]);
        INIT_LIST_HEAD(&tsk->cpu_timers[2]);
 }
+#else
+static inline void posix_cpu_timers_init(struct task_struct *tsk) { }
+#endif
 
 static inline void
 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 2516b8d..a688a82 100644 (file)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2246,6 +2246,7 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
        }
 }
 
+#ifdef CONFIG_POSIX_TIMERS
 static void watchdog(struct rq *rq, struct task_struct *p)
 {
        unsigned long soft, hard;
@@ -2267,6 +2268,9 @@ static void watchdog(struct rq *rq, struct task_struct *p)
                        p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
        }
 }
+#else
+static inline void watchdog(struct rq *rq, struct task_struct *p) { }
+#endif
 
 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
 {

diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 34659a8..c69a987 100644 (file)
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -172,18 +172,19 @@ sched_info_switch(struct rq *rq,
  */
 
 /**
- * cputimer_running - return true if cputimer is running
+ * get_running_cputimer - return &tsk->signal->cputimer if cputimer is running
  *
  * @tsk:       Pointer to target task.
  */
-static inline bool cputimer_running(struct task_struct *tsk)
-
+#ifdef CONFIG_POSIX_TIMERS
+static inline
+struct thread_group_cputimer *get_running_cputimer(struct task_struct *tsk)
 {
        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 
        /* Check if cputimer isn't running. This is accessed without locking. */
        if (!READ_ONCE(cputimer->running))
-               return false;
+               return NULL;
 
        /*
         * After we flush the task's sum_exec_runtime to sig->sum_sched_runtime
@@ -200,10 +201,17 @@ static inline bool cputimer_running(struct task_struct *tsk)
         * clock delta is behind the expiring timer value.
         */
        if (unlikely(!tsk->sighand))
-               return false;
+               return NULL;
 
-       return true;
+       return cputimer;
+}
+#else
+static inline
+struct thread_group_cputimer *get_running_cputimer(struct task_struct *tsk)
+{
+       return NULL;
 }
+#endif
 
 /**
  * account_group_user_time - Maintain utime for a thread group.
@@ -218,9 +226,9 @@ static inline bool cputimer_running(struct task_struct *tsk)
 static inline void account_group_user_time(struct task_struct *tsk,
                                           cputime_t cputime)
 {
-       struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+       struct thread_group_cputimer *cputimer = get_running_cputimer(tsk);
 
-       if (!cputimer_running(tsk))
+       if (!cputimer)
                return;
 
        atomic64_add(cputime, &cputimer->cputime_atomic.utime);
@@ -239,9 +247,9 @@ static inline void account_group_user_time(struct task_struct *tsk,
 static inline void account_group_system_time(struct task_struct *tsk,
                                             cputime_t cputime)
 {
-       struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+       struct thread_group_cputimer *cputimer = get_running_cputimer(tsk);
 
-       if (!cputimer_running(tsk))
+       if (!cputimer)
                return;
 
        atomic64_add(cputime, &cputimer->cputime_atomic.stime);
@@ -260,9 +268,9 @@ static inline void account_group_system_time(struct task_struct *tsk,
 static inline void account_group_exec_runtime(struct task_struct *tsk,
                                              unsigned long long ns)
 {
-       struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+       struct thread_group_cputimer *cputimer = get_running_cputimer(tsk);
 
-       if (!cputimer_running(tsk))
+       if (!cputimer)
                return;
 
        atomic64_add(ns, &cputimer->cputime_atomic.sum_exec_runtime);