string: factorize skip_spaces and export it to be generally available
[safe/jmp/linux-2.6] / kernel / posix-cpu-timers.c
index db107c9..438ff45 100644 (file)
@@ -8,17 +8,18 @@
 #include <linux/math64.h>
 #include <asm/uaccess.h>
 #include <linux/kernel_stat.h>
+#include <trace/events/timer.h>
 
 /*
  * Called after updating RLIMIT_CPU to set timer expiration if necessary.
  */
 void update_rlimit_cpu(unsigned long rlim_new)
 {
-       cputime_t cputime;
+       cputime_t cputime = secs_to_cputime(rlim_new);
+       struct signal_struct *const sig = current->signal;
 
-       cputime = secs_to_cputime(rlim_new);
-       if (cputime_eq(current->signal->it_prof_expires, cputime_zero) ||
-           cputime_lt(current->signal->it_prof_expires, cputime)) {
+       if (cputime_eq(sig->it[CPUCLOCK_PROF].expires, cputime_zero) ||
+           cputime_gt(sig->it[CPUCLOCK_PROF].expires, cputime)) {
                spin_lock_irq(&current->sighand->siglock);
                set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
                spin_unlock_irq(&current->sighand->siglock);
@@ -224,7 +225,7 @@ 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 = p->se.sum_exec_runtime + task_delta_exec(p);
+               cpu->sched = task_sched_runtime(p);
                break;
        }
        return 0;
@@ -261,6 +262,40 @@ out:
        rcu_read_unlock();
 }
 
+static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
+{
+       if (cputime_gt(b->utime, a->utime))
+               a->utime = b->utime;
+
+       if (cputime_gt(b->stime, a->stime))
+               a->stime = b->stime;
+
+       if (b->sum_exec_runtime > a->sum_exec_runtime)
+               a->sum_exec_runtime = b->sum_exec_runtime;
+}
+
+void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
+{
+       struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+       struct task_cputime sum;
+       unsigned long flags;
+
+       spin_lock_irqsave(&cputimer->lock, flags);
+       if (!cputimer->running) {
+               cputimer->running = 1;
+               /*
+                * The POSIX timer interface allows for absolute time expiry
+                * values through the TIMER_ABSTIME flag, therefore we have
+                * to synchronize the timer to the clock every time we start
+                * it.
+                */
+               thread_group_cputime(tsk, &sum);
+               update_gt_cputime(&cputimer->cputime, &sum);
+       }
+       *times = cputimer->cputime;
+       spin_unlock_irqrestore(&cputimer->lock, flags);
+}
+
 /*
  * Sample a process (thread group) clock for the given group_leader task.
  * Must be called with tasklist_lock held for reading.
@@ -271,18 +306,19 @@ static int cpu_clock_sample_group(const clockid_t which_clock,
 {
        struct task_cputime cputime;
 
-       thread_group_cputime(p, &cputime);
        switch (CPUCLOCK_WHICH(which_clock)) {
        default:
                return -EINVAL;
        case CPUCLOCK_PROF:
+               thread_group_cputime(p, &cputime);
                cpu->cpu = cputime_add(cputime.utime, cputime.stime);
                break;
        case CPUCLOCK_VIRT:
+               thread_group_cputime(p, &cputime);
                cpu->cpu = cputime.utime;
                break;
        case CPUCLOCK_SCHED:
-               cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
+               cpu->sched = thread_group_sched_runtime(p);
                break;
        }
        return 0;
@@ -348,7 +384,8 @@ int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
 
 /*
  * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
- * This is called from sys_timer_create with the new timer already locked.
+ * This is called from sys_timer_create() and do_cpu_nanosleep() with the
+ * new timer already all-zeros initialized.
  */
 int posix_cpu_timer_create(struct k_itimer *new_timer)
 {
@@ -360,8 +397,6 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
                return -EINVAL;
 
        INIT_LIST_HEAD(&new_timer->it.cpu.entry);
-       new_timer->it.cpu.incr.sched = 0;
-       new_timer->it.cpu.expires.sched = 0;
 
        read_lock(&tasklist_lock);
        if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
@@ -486,11 +521,12 @@ void posix_cpu_timers_exit(struct task_struct *tsk)
 }
 void posix_cpu_timers_exit_group(struct task_struct *tsk)
 {
-       struct task_cputime cputime;
+       struct signal_struct *const sig = tsk->signal;
 
-       thread_group_cputime(tsk, &cputime);
        cleanup_timers(tsk->signal->cpu_timers,
-                      cputime.utime, cputime.stime, cputime.sum_exec_runtime);
+                      cputime_add(tsk->utime, sig->utime),
+                      cputime_add(tsk->stime, sig->stime),
+                      tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
 }
 
 static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
@@ -506,29 +542,17 @@ static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
                                             now);
 }
 
-/*
- * Enable the process wide cpu timer accounting.
- *
- * serialized using ->sighand->siglock
- */
-static void start_process_timers(struct task_struct *tsk)
+static inline int expires_gt(cputime_t expires, cputime_t new_exp)
 {
-       tsk->signal->cputimer.running = 1;
-       barrier();
+       return cputime_eq(expires, cputime_zero) ||
+              cputime_gt(expires, new_exp);
 }
 
-/*
- * Release the process wide timer accounting -- timer stops ticking when
- * nobody cares about it.
- *
- * serialized using ->sighand->siglock
- */
-static void stop_process_timers(struct task_struct *tsk)
+static inline int expires_le(cputime_t expires, cputime_t new_exp)
 {
-       tsk->signal->cputimer.running = 0;
-       barrier();
+       return !cputime_eq(expires, cputime_zero) &&
+              cputime_le(expires, new_exp);
 }
-
 /*
  * Insert the timer on the appropriate list before any timers that
  * expire later.  This must be called with the tasklist_lock held
@@ -549,9 +573,6 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
        BUG_ON(!irqs_disabled());
        spin_lock(&p->sighand->siglock);
 
-       if (!CPUCLOCK_PERTHREAD(timer->it_clock))
-               start_process_timers(p);
-
        listpos = head;
        if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
                list_for_each_entry(next, head, entry) {
@@ -576,34 +597,32 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
                 */
 
                if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
+                       union cpu_time_count *exp = &nt->expires;
+
                        switch (CPUCLOCK_WHICH(timer->it_clock)) {
                        default:
                                BUG();
                        case CPUCLOCK_PROF:
-                               if (cputime_eq(p->cputime_expires.prof_exp,
-                                              cputime_zero) ||
-                                   cputime_gt(p->cputime_expires.prof_exp,
-                                              nt->expires.cpu))
-                                       p->cputime_expires.prof_exp =
-                                               nt->expires.cpu;
+                               if (expires_gt(p->cputime_expires.prof_exp,
+                                              exp->cpu))
+                                       p->cputime_expires.prof_exp = exp->cpu;
                                break;
                        case CPUCLOCK_VIRT:
-                               if (cputime_eq(p->cputime_expires.virt_exp,
-                                              cputime_zero) ||
-                                   cputime_gt(p->cputime_expires.virt_exp,
-                                              nt->expires.cpu))
-                                       p->cputime_expires.virt_exp =
-                                               nt->expires.cpu;
+                               if (expires_gt(p->cputime_expires.virt_exp,
+                                              exp->cpu))
+                                       p->cputime_expires.virt_exp = exp->cpu;
                                break;
                        case CPUCLOCK_SCHED:
                                if (p->cputime_expires.sched_exp == 0 ||
-                                   p->cputime_expires.sched_exp >
-                                                       nt->expires.sched)
+                                   p->cputime_expires.sched_exp > exp->sched)
                                        p->cputime_expires.sched_exp =
-                                               nt->expires.sched;
+                                                               exp->sched;
                                break;
                        }
                } else {
+                       struct signal_struct *const sig = p->signal;
+                       union cpu_time_count *exp = &timer->it.cpu.expires;
+
                        /*
                         * For a process timer, set the cached expiration time.
                         */
@@ -611,30 +630,23 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
                        default:
                                BUG();
                        case CPUCLOCK_VIRT:
-                               if (!cputime_eq(p->signal->it_virt_expires,
-                                               cputime_zero) &&
-                                   cputime_lt(p->signal->it_virt_expires,
-                                              timer->it.cpu.expires.cpu))
+                               if (expires_le(sig->it[CPUCLOCK_VIRT].expires,
+                                              exp->cpu))
                                        break;
-                               p->signal->cputime_expires.virt_exp =
-                                       timer->it.cpu.expires.cpu;
+                               sig->cputime_expires.virt_exp = exp->cpu;
                                break;
                        case CPUCLOCK_PROF:
-                               if (!cputime_eq(p->signal->it_prof_expires,
-                                               cputime_zero) &&
-                                   cputime_lt(p->signal->it_prof_expires,
-                                              timer->it.cpu.expires.cpu))
+                               if (expires_le(sig->it[CPUCLOCK_PROF].expires,
+                                              exp->cpu))
                                        break;
-                               i = p->signal->rlim[RLIMIT_CPU].rlim_cur;
+                               i = sig->rlim[RLIMIT_CPU].rlim_cur;
                                if (i != RLIM_INFINITY &&
-                                   i <= cputime_to_secs(timer->it.cpu.expires.cpu))
+                                   i <= cputime_to_secs(exp->cpu))
                                        break;
-                               p->signal->cputime_expires.prof_exp =
-                                       timer->it.cpu.expires.cpu;
+                               sig->cputime_expires.prof_exp = exp->cpu;
                                break;
                        case CPUCLOCK_SCHED:
-                               p->signal->cputime_expires.sched_exp =
-                                       timer->it.cpu.expires.sched;
+                               sig->cputime_expires.sched_exp = exp->sched;
                                break;
                        }
                }
@@ -673,6 +685,33 @@ static void cpu_timer_fire(struct k_itimer *timer)
 }
 
 /*
+ * Sample a process (thread group) timer for the given group_leader task.
+ * Must be called with tasklist_lock held for reading.
+ */
+static int cpu_timer_sample_group(const clockid_t which_clock,
+                                 struct task_struct *p,
+                                 union cpu_time_count *cpu)
+{
+       struct task_cputime cputime;
+
+       thread_group_cputimer(p, &cputime);
+       switch (CPUCLOCK_WHICH(which_clock)) {
+       default:
+               return -EINVAL;
+       case CPUCLOCK_PROF:
+               cpu->cpu = cputime_add(cputime.utime, cputime.stime);
+               break;
+       case CPUCLOCK_VIRT:
+               cpu->cpu = cputime.utime;
+               break;
+       case CPUCLOCK_SCHED:
+               cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
+               break;
+       }
+       return 0;
+}
+
+/*
  * Guts of sys_timer_settime for CPU timers.
  * This is called with the timer locked and interrupts disabled.
  * If we return TIMER_RETRY, it's necessary to release the timer's lock
@@ -733,7 +772,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
                cpu_clock_sample(timer->it_clock, p, &val);
        } else {
-               cpu_clock_sample_group(timer->it_clock, p, &val);
+               cpu_timer_sample_group(timer->it_clock, p, &val);
        }
 
        if (old) {
@@ -881,7 +920,7 @@ void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
                        read_unlock(&tasklist_lock);
                        goto dead;
                } else {
-                       cpu_clock_sample_group(timer->it_clock, p, &now);
+                       cpu_timer_sample_group(timer->it_clock, p, &now);
                        clear_dead = (unlikely(p->exit_state) &&
                                      thread_group_empty(p));
                }
@@ -1021,6 +1060,53 @@ static void check_thread_timers(struct task_struct *tsk,
        }
 }
 
+static void stop_process_timers(struct task_struct *tsk)
+{
+       struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+       unsigned long flags;
+
+       if (!cputimer->running)
+               return;
+
+       spin_lock_irqsave(&cputimer->lock, flags);
+       cputimer->running = 0;
+       spin_unlock_irqrestore(&cputimer->lock, flags);
+}
+
+static u32 onecputick;
+
+static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
+                            cputime_t *expires, cputime_t cur_time, int signo)
+{
+       if (cputime_eq(it->expires, cputime_zero))
+               return;
+
+       if (cputime_ge(cur_time, it->expires)) {
+               if (!cputime_eq(it->incr, cputime_zero)) {
+                       it->expires = cputime_add(it->expires, it->incr);
+                       it->error += it->incr_error;
+                       if (it->error >= onecputick) {
+                               it->expires = cputime_sub(it->expires,
+                                                         cputime_one_jiffy);
+                               it->error -= onecputick;
+                       }
+               } else {
+                       it->expires = cputime_zero;
+               }
+
+               trace_itimer_expire(signo == SIGPROF ?
+                                   ITIMER_PROF : ITIMER_VIRTUAL,
+                                   tsk->signal->leader_pid, cur_time);
+               __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
+       }
+
+       if (!cputime_eq(it->expires, cputime_zero) &&
+           (cputime_eq(*expires, cputime_zero) ||
+            cputime_lt(it->expires, *expires))) {
+               *expires = it->expires;
+       }
+}
+
 /*
  * Check for any per-thread CPU timers that have fired and move them
  * off the tsk->*_timers list onto the firing list.  Per-thread timers
@@ -1040,10 +1126,10 @@ static void check_process_timers(struct task_struct *tsk,
         * Don't sample the current process CPU clocks if there are no timers.
         */
        if (list_empty(&timers[CPUCLOCK_PROF]) &&
-           cputime_eq(sig->it_prof_expires, cputime_zero) &&
+           cputime_eq(sig->it[CPUCLOCK_PROF].expires, cputime_zero) &&
            sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&
            list_empty(&timers[CPUCLOCK_VIRT]) &&
-           cputime_eq(sig->it_virt_expires, cputime_zero) &&
+           cputime_eq(sig->it[CPUCLOCK_VIRT].expires, cputime_zero) &&
            list_empty(&timers[CPUCLOCK_SCHED])) {
                stop_process_timers(tsk);
                return;
@@ -1103,38 +1189,11 @@ static void check_process_timers(struct task_struct *tsk,
        /*
         * Check for the special case process timers.
         */
-       if (!cputime_eq(sig->it_prof_expires, cputime_zero)) {
-               if (cputime_ge(ptime, sig->it_prof_expires)) {
-                       /* ITIMER_PROF fires and reloads.  */
-                       sig->it_prof_expires = sig->it_prof_incr;
-                       if (!cputime_eq(sig->it_prof_expires, cputime_zero)) {
-                               sig->it_prof_expires = cputime_add(
-                                       sig->it_prof_expires, ptime);
-                       }
-                       __group_send_sig_info(SIGPROF, SEND_SIG_PRIV, tsk);
-               }
-               if (!cputime_eq(sig->it_prof_expires, cputime_zero) &&
-                   (cputime_eq(prof_expires, cputime_zero) ||
-                    cputime_lt(sig->it_prof_expires, prof_expires))) {
-                       prof_expires = sig->it_prof_expires;
-               }
-       }
-       if (!cputime_eq(sig->it_virt_expires, cputime_zero)) {
-               if (cputime_ge(utime, sig->it_virt_expires)) {
-                       /* ITIMER_VIRTUAL fires and reloads.  */
-                       sig->it_virt_expires = sig->it_virt_incr;
-                       if (!cputime_eq(sig->it_virt_expires, cputime_zero)) {
-                               sig->it_virt_expires = cputime_add(
-                                       sig->it_virt_expires, utime);
-                       }
-                       __group_send_sig_info(SIGVTALRM, SEND_SIG_PRIV, tsk);
-               }
-               if (!cputime_eq(sig->it_virt_expires, cputime_zero) &&
-                   (cputime_eq(virt_expires, cputime_zero) ||
-                    cputime_lt(sig->it_virt_expires, virt_expires))) {
-                       virt_expires = sig->it_virt_expires;
-               }
-       }
+       check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
+                        SIGPROF);
+       check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
+                        SIGVTALRM);
+
        if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
                unsigned long psecs = cputime_to_secs(ptime);
                cputime_t x;
@@ -1223,7 +1282,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
                        clear_dead_task(timer, now);
                        goto out_unlock;
                }
-               cpu_clock_sample_group(timer->it_clock, p, &now);
+               cpu_timer_sample_group(timer->it_clock, p, &now);
                bump_cpu_timer(timer, now);
                /* Leave the tasklist_lock locked for the call below.  */
        }
@@ -1322,7 +1381,8 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
                if (task_cputime_expired(&group_sample, &sig->cputime_expires))
                        return 1;
        }
-       return 0;
+
+       return sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY;
 }
 
 /*
@@ -1370,51 +1430,24 @@ void run_posix_cpu_timers(struct task_struct *tsk)
         * timer call will interfere.
         */
        list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
-               int firing;
+               int cpu_firing;
+
                spin_lock(&timer->it_lock);
                list_del_init(&timer->it.cpu.entry);
-               firing = timer->it.cpu.firing;
+               cpu_firing = timer->it.cpu.firing;
                timer->it.cpu.firing = 0;
                /*
                 * The firing flag is -1 if we collided with a reset
                 * of the timer, which already reported this
                 * almost-firing as an overrun.  So don't generate an event.
                 */
-               if (likely(firing >= 0)) {
+               if (likely(cpu_firing >= 0))
                        cpu_timer_fire(timer);
-               }
                spin_unlock(&timer->it_lock);
        }
 }
 
 /*
- * Sample a process (thread group) timer for the given group_leader task.
- * Must be called with tasklist_lock held for reading.
- */
-static int cpu_timer_sample_group(const clockid_t which_clock,
-                                 struct task_struct *p,
-                                 union cpu_time_count *cpu)
-{
-       struct task_cputime cputime;
-
-       thread_group_cputimer(p, &cputime);
-       switch (CPUCLOCK_WHICH(which_clock)) {
-       default:
-               return -EINVAL;
-       case CPUCLOCK_PROF:
-               cpu->cpu = cputime_add(cputime.utime, cputime.stime);
-               break;
-       case CPUCLOCK_VIRT:
-               cpu->cpu = cputime.utime;
-               break;
-       case CPUCLOCK_SCHED:
-               cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
-               break;
-       }
-       return 0;
-}
-
-/*
  * Set one of the process-wide special case CPU timers.
  * The tsk->sighand->siglock must be held by the caller.
  * The *newval argument is relative and we update it to be absolute, *oldval
@@ -1427,14 +1460,13 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
        struct list_head *head;
 
        BUG_ON(clock_idx == CPUCLOCK_SCHED);
-       start_process_timers(tsk);
        cpu_timer_sample_group(clock_idx, tsk, &now);
 
        if (oldval) {
                if (!cputime_eq(*oldval, cputime_zero)) {
                        if (cputime_le(*oldval, now.cpu)) {
                                /* Just about to fire. */
-                               *oldval = jiffies_to_cputime(1);
+                               *oldval = cputime_one_jiffy;
                        } else {
                                *oldval = cputime_sub(*oldval, now.cpu);
                        }
@@ -1680,10 +1712,15 @@ static __init int init_posix_cpu_timers(void)
                .nsleep = thread_cpu_nsleep,
                .nsleep_restart = thread_cpu_nsleep_restart,
        };
+       struct timespec ts;
 
        register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
        register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
 
+       cputime_to_timespec(cputime_one_jiffy, &ts);
+       onecputick = ts.tv_nsec;
+       WARN_ON(ts.tv_sec != 0);
+
        return 0;
 }
 __initcall(init_posix_cpu_timers);