1 files changed, 112 insertions, 75 deletions

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 157de3a47832..2313a4cc14ea 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -10,76 +10,6 @@
 #include <linux/kernel_stat.h>
 
 /*
- * Allocate the thread_group_cputime structure appropriately and fill in the
- * current values of the fields.  Called from copy_signal() via
- * thread_group_cputime_clone_thread() when adding a second or subsequent
- * thread to a thread group.  Assumes interrupts are enabled when called.
- */
-int thread_group_cputime_alloc(struct task_struct *tsk)
-{
-        struct signal_struct *sig = tsk->signal;
-        struct task_cputime *cputime;
-
-        /*
-         * If we have multiple threads and we don't already have a
-         * per-CPU task_cputime struct (checked in the caller), allocate
-         * one and fill it in with the times accumulated so far.  We may
-         * race with another thread so recheck after we pick up the sighand
-         * lock.
-         */
-        cputime = alloc_percpu(struct task_cputime);
-        if (cputime == NULL)
-                return -ENOMEM;
-        spin_lock_irq(&tsk->sighand->siglock);
-        if (sig->cputime.totals) {
-                spin_unlock_irq(&tsk->sighand->siglock);
-                free_percpu(cputime);
-                return 0;
-        }
-        sig->cputime.totals = cputime;
-        cputime = per_cpu_ptr(sig->cputime.totals, smp_processor_id());
-        cputime->utime = tsk->utime;
-        cputime->stime = tsk->stime;
-        cputime->sum_exec_runtime = tsk->se.sum_exec_runtime;
-        spin_unlock_irq(&tsk->sighand->siglock);
-        return 0;
-}
-
-/**
- * thread_group_cputime - Sum the thread group time fields across all CPUs.
- *
- * @tsk:        The task we use to identify the thread group.
- * @times:      task_cputime structure in which we return the summed fields.
- *
- * Walk the list of CPUs to sum the per-CPU time fields in the thread group
- * time structure.
- */
-void thread_group_cputime(
-        struct task_struct *tsk,
-        struct task_cputime *times)
-{
-        struct task_cputime *totals, *tot;
-        int i;
-
-        totals = tsk->signal->cputime.totals;
-        if (!totals) {
-                times->utime = tsk->utime;
-                times->stime = tsk->stime;
-                times->sum_exec_runtime = tsk->se.sum_exec_runtime;
-                return;
-        }
-
-        times->stime = times->utime = cputime_zero;
-        times->sum_exec_runtime = 0;
-        for_each_possible_cpu(i) {
-                tot = per_cpu_ptr(totals, i);
-                times->utime = cputime_add(times->utime, tot->utime);
-                times->stime = cputime_add(times->stime, tot->stime);
-                times->sum_exec_runtime += tot->sum_exec_runtime;
-        }
-}
-
-/*
  * Called after updating RLIMIT_CPU to set timer expiration if necessary.
  */
 void update_rlimit_cpu(unsigned long rlim_new)
@@ -300,6 +230,71 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
         return 0;
 }
 
+void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
+{
+        struct sighand_struct *sighand;
+        struct signal_struct *sig;
+        struct task_struct *t;
+
+        *times = INIT_CPUTIME;
+
+        rcu_read_lock();
+        sighand = rcu_dereference(tsk->sighand);
+        if (!sighand)
+                goto out;
+
+        sig = tsk->signal;
+
+        t = tsk;
+        do {
+                times->utime = cputime_add(times->utime, t->utime);
+                times->stime = cputime_add(times->stime, t->stime);
+                times->sum_exec_runtime += t->se.sum_exec_runtime;
+
+                t = next_thread(t);
+        } while (t != tsk);
+
+        times->utime = cputime_add(times->utime, sig->utime);
+        times->stime = cputime_add(times->stime, sig->stime);
+        times->sum_exec_runtime += sig->sum_sched_runtime;
+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.
@@ -527,7 +522,7 @@ void posix_cpu_timers_exit_group(struct task_struct *tsk)
 {
         struct task_cputime cputime;
 
-        thread_group_cputime(tsk, &cputime);
+        thread_group_cputimer(tsk, &cputime);
         cleanup_timers(tsk->signal->cpu_timers,
                        cputime.utime, cputime.stime, cputime.sum_exec_runtime);
 }
@@ -1034,6 +1029,19 @@ 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);
+}
+
 /*
  * 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
@@ -1057,13 +1065,15 @@ static void check_process_timers(struct task_struct *tsk,
             sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&
             list_empty(&timers[CPUCLOCK_VIRT]) &&
             cputime_eq(sig->it_virt_expires, cputime_zero) &&
-            list_empty(&timers[CPUCLOCK_SCHED]))
+            list_empty(&timers[CPUCLOCK_SCHED])) {
+                stop_process_timers(tsk);
                 return;
+        }
 
         /*
          * Collect the current process totals.
          */
-        thread_group_cputime(tsk, &cputime);
+        thread_group_cputimer(tsk, &cputime);
         utime = cputime.utime;
         ptime = cputime_add(utime, cputime.stime);
         sum_sched_runtime = cputime.sum_exec_runtime;
@@ -1329,7 +1339,7 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
         if (!task_cputime_zero(&sig->cputime_expires)) {
                 struct task_cputime group_sample;
 
-                thread_group_cputime(tsk, &group_sample);
+                thread_group_cputimer(tsk, &group_sample);
                 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
                         return 1;
         }
@@ -1399,6 +1409,33 @@ void run_posix_cpu_timers(struct task_struct *tsk)
 }
 
 /*
+ * 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
@@ -1411,7 +1448,7 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
         struct list_head *head;
 
         BUG_ON(clock_idx == CPUCLOCK_SCHED);
-        cpu_clock_sample_group(clock_idx, tsk, &now);
+        cpu_timer_sample_group(clock_idx, tsk, &now);
 
         if (oldval) {
                 if (!cputime_eq(*oldval, cputime_zero)) {