timers: fix itimer/many thread hang

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / itimer.c

diff --git a/kernel/itimer.c b/kernel/itimer.c
index ab982747d9bd8121c19b3327b96c7760adb7577e..db7c358b9a02f1cc50954517124c8272b5eed463 100644 (file)
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -55,17 +55,15 @@ int do_getitimer(int which, struct itimerval *value)
                spin_unlock_irq(&tsk->sighand->siglock);
                break;
        case ITIMER_VIRTUAL:
-               read_lock(&tasklist_lock);
                spin_lock_irq(&tsk->sighand->siglock);
                cval = tsk->signal->it_virt_expires;
                cinterval = tsk->signal->it_virt_incr;
                if (!cputime_eq(cval, cputime_zero)) {
-                       struct task_struct *t = tsk;
-                       cputime_t utime = tsk->signal->utime;
-                       do {
-                               utime = cputime_add(utime, t->utime);
-                               t = next_thread(t);
-                       } while (t != tsk);
+                       struct task_cputime cputime;
+                       cputime_t utime;
+
+                       thread_group_cputime(tsk, &cputime);
+                       utime = cputime.utime;
                        if (cputime_le(cval, utime)) { /* about to fire */
                                cval = jiffies_to_cputime(1);
                        } else {
@@ -73,25 +71,19 @@ int do_getitimer(int which, struct itimerval *value)
                        }
                }
                spin_unlock_irq(&tsk->sighand->siglock);
-               read_unlock(&tasklist_lock);
                cputime_to_timeval(cval, &value->it_value);
                cputime_to_timeval(cinterval, &value->it_interval);
                break;
        case ITIMER_PROF:
-               read_lock(&tasklist_lock);
                spin_lock_irq(&tsk->sighand->siglock);
                cval = tsk->signal->it_prof_expires;
                cinterval = tsk->signal->it_prof_incr;
                if (!cputime_eq(cval, cputime_zero)) {
-                       struct task_struct *t = tsk;
-                       cputime_t ptime = cputime_add(tsk->signal->utime,
-                                                     tsk->signal->stime);
-                       do {
-                               ptime = cputime_add(ptime,
-                                                   cputime_add(t->utime,
-                                                               t->stime));
-                               t = next_thread(t);
-                       } while (t != tsk);
+                       struct task_cputime times;
+                       cputime_t ptime;
+
+                       thread_group_cputime(tsk, &times);
+                       ptime = cputime_add(times.utime, times.stime);
                        if (cputime_le(cval, ptime)) { /* about to fire */
                                cval = jiffies_to_cputime(1);
                        } else {
@@ -99,7 +91,6 @@ int do_getitimer(int which, struct itimerval *value)
                        }
                }
                spin_unlock_irq(&tsk->sighand->siglock);
-               read_unlock(&tasklist_lock);
                cputime_to_timeval(cval, &value->it_value);
                cputime_to_timeval(cinterval, &value->it_interval);
                break;
@@ -185,7 +176,6 @@ again:
        case ITIMER_VIRTUAL:
                nval = timeval_to_cputime(&value->it_value);
                ninterval = timeval_to_cputime(&value->it_interval);
-               read_lock(&tasklist_lock);
                spin_lock_irq(&tsk->sighand->siglock);
                cval = tsk->signal->it_virt_expires;
                cinterval = tsk->signal->it_virt_incr;
@@ -200,7 +190,6 @@ again:
                tsk->signal->it_virt_expires = nval;
                tsk->signal->it_virt_incr = ninterval;
                spin_unlock_irq(&tsk->sighand->siglock);
-               read_unlock(&tasklist_lock);
                if (ovalue) {
                        cputime_to_timeval(cval, &ovalue->it_value);
                        cputime_to_timeval(cinterval, &ovalue->it_interval);
@@ -209,7 +198,6 @@ again:
        case ITIMER_PROF:
                nval = timeval_to_cputime(&value->it_value);
                ninterval = timeval_to_cputime(&value->it_interval);
-               read_lock(&tasklist_lock);
                spin_lock_irq(&tsk->sighand->siglock);
                cval = tsk->signal->it_prof_expires;
                cinterval = tsk->signal->it_prof_incr;
@@ -224,7 +212,6 @@ again:
                tsk->signal->it_prof_expires = nval;
                tsk->signal->it_prof_incr = ninterval;
                spin_unlock_irq(&tsk->sighand->siglock);
-               read_unlock(&tasklist_lock);
                if (ovalue) {
                        cputime_to_timeval(cval, &ovalue->it_value);
                        cputime_to_timeval(cinterval, &ovalue->it_interval);