return a;
}
+/*
+ * Divide and limit the result to res >= 1
+ *
+ * This is necessary to prevent signal delivery starvation, when the result of
+ * the division would be rounded down to 0.
+ */
+static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
+{
+ cputime_t res = cputime_div(time, div);
+
+ return max_t(cputime_t, res, 1);
+}
+
/*
* Update expiry time from increment, and increase overrun count,
* given the current clock sample.
* should be able to see it.
*/
struct task_struct *p;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_task_by_pid(pid);
if (p) {
if (CPUCLOCK_PERTHREAD(which_clock)) {
error = cpu_clock_sample(which_clock,
p, &rtn);
}
- } else if (p->tgid == pid && p->signal) {
- error = cpu_clock_sample_group(which_clock,
- p, &rtn);
+ } else {
+ read_lock(&tasklist_lock);
+ if (p->tgid == pid && p->signal) {
+ error =
+ cpu_clock_sample_group(which_clock,
+ p, &rtn);
+ }
+ read_unlock(&tasklist_lock);
}
}
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
}
if (error)
BUG();
break;
case CPUCLOCK_PROF:
- left = cputime_div(cputime_sub(expires.cpu, val.cpu),
- nthreads);
+ left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu),
+ nthreads);
do {
if (likely(!(t->flags & PF_EXITING))) {
ticks = cputime_add(prof_ticks(t), left);
} while (t != p);
break;
case CPUCLOCK_VIRT:
- left = cputime_div(cputime_sub(expires.cpu, val.cpu),
- nthreads);
+ left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu),
+ nthreads);
do {
if (likely(!(t->flags & PF_EXITING))) {
ticks = cputime_add(virt_ticks(t), left);
case CPUCLOCK_SCHED:
nsleft = expires.sched - val.sched;
do_div(nsleft, nthreads);
+ nsleft = max_t(unsigned long long, nsleft, 1);
do {
if (likely(!(t->flags & PF_EXITING))) {
ns = t->sched_time + nsleft;
prof_left = cputime_sub(prof_expires, utime);
prof_left = cputime_sub(prof_left, stime);
- prof_left = cputime_div(prof_left, nthreads);
+ prof_left = cputime_div_non_zero(prof_left, nthreads);
virt_left = cputime_sub(virt_expires, utime);
- virt_left = cputime_div(virt_left, nthreads);
+ virt_left = cputime_div_non_zero(virt_left, nthreads);
if (sched_expires) {
sched_left = sched_expires - sched_time;
do_div(sched_left, nthreads);
+ sched_left = max_t(unsigned long long, sched_left, 1);
} else {
sched_left = 0;
}
}
}
-static long posix_cpu_clock_nanosleep_restart(struct restart_block *);
-
-int posix_cpu_nsleep(const clockid_t which_clock, int flags,
- struct timespec *rqtp, struct timespec __user *rmtp)
+static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
+ struct timespec *rqtp, struct itimerspec *it)
{
- struct restart_block *restart_block =
- ¤t_thread_info()->restart_block;
struct k_itimer timer;
int error;
- /*
- * Diagnose required errors first.
- */
- if (CPUCLOCK_PERTHREAD(which_clock) &&
- (CPUCLOCK_PID(which_clock) == 0 ||
- CPUCLOCK_PID(which_clock) == current->pid))
- return -EINVAL;
-
/*
* Set up a temporary timer and then wait for it to go off.
*/
timer.it_process = current;
if (!error) {
static struct itimerspec zero_it;
- struct itimerspec it = { .it_value = *rqtp,
- .it_interval = {} };
+
+ memset(it, 0, sizeof *it);
+ it->it_value = *rqtp;
spin_lock_irq(&timer.it_lock);
- error = posix_cpu_timer_set(&timer, flags, &it, NULL);
+ error = posix_cpu_timer_set(&timer, flags, it, NULL);
if (error) {
spin_unlock_irq(&timer.it_lock);
return error;
* We were interrupted by a signal.
*/
sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
- posix_cpu_timer_set(&timer, 0, &zero_it, &it);
+ posix_cpu_timer_set(&timer, 0, &zero_it, it);
spin_unlock_irq(&timer.it_lock);
- if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
+ if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
/*
* It actually did fire already.
*/
return 0;
}
+ error = -ERESTART_RESTARTBLOCK;
+ }
+
+ return error;
+}
+
+int posix_cpu_nsleep(const clockid_t which_clock, int flags,
+ struct timespec *rqtp, struct timespec __user *rmtp)
+{
+ struct restart_block *restart_block =
+ ¤t_thread_info()->restart_block;
+ struct itimerspec it;
+ int error;
+
+ /*
+ * Diagnose required errors first.
+ */
+ if (CPUCLOCK_PERTHREAD(which_clock) &&
+ (CPUCLOCK_PID(which_clock) == 0 ||
+ CPUCLOCK_PID(which_clock) == current->pid))
+ return -EINVAL;
+
+ error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
+
+ if (error == -ERESTART_RESTARTBLOCK) {
+
+ if (flags & TIMER_ABSTIME)
+ return -ERESTARTNOHAND;
/*
- * Report back to the user the time still remaining.
- */
- if (rmtp != NULL && !(flags & TIMER_ABSTIME) &&
- copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
+ * Report back to the user the time still remaining.
+ */
+ if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
return -EFAULT;
- restart_block->fn = posix_cpu_clock_nanosleep_restart;
- /* Caller already set restart_block->arg1 */
+ restart_block->fn = posix_cpu_nsleep_restart;
restart_block->arg0 = which_clock;
restart_block->arg1 = (unsigned long) rmtp;
restart_block->arg2 = rqtp->tv_sec;
restart_block->arg3 = rqtp->tv_nsec;
-
- error = -ERESTART_RESTARTBLOCK;
}
-
return error;
}
-static long
-posix_cpu_clock_nanosleep_restart(struct restart_block *restart_block)
+long posix_cpu_nsleep_restart(struct restart_block *restart_block)
{
clockid_t which_clock = restart_block->arg0;
struct timespec __user *rmtp;
struct timespec t;
+ struct itimerspec it;
+ int error;
rmtp = (struct timespec __user *) restart_block->arg1;
t.tv_sec = restart_block->arg2;
t.tv_nsec = restart_block->arg3;
restart_block->fn = do_no_restart_syscall;
- return posix_cpu_nsleep(which_clock, TIMER_ABSTIME, &t, rmtp);
+ error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
+
+ if (error == -ERESTART_RESTARTBLOCK) {
+ /*
+ * Report back to the user the time still remaining.
+ */
+ if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
+ return -EFAULT;
+
+ restart_block->fn = posix_cpu_nsleep_restart;
+ restart_block->arg0 = which_clock;
+ restart_block->arg1 = (unsigned long) rmtp;
+ restart_block->arg2 = t.tv_sec;
+ restart_block->arg3 = t.tv_nsec;
+ }
+ return error;
+
}
{
return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
}
+static long process_cpu_nsleep_restart(struct restart_block *restart_block)
+{
+ return -EINVAL;
+}
static int thread_cpu_clock_getres(const clockid_t which_clock,
struct timespec *tp)
{
{
return -EINVAL;
}
+static long thread_cpu_nsleep_restart(struct restart_block *restart_block)
+{
+ return -EINVAL;
+}
static __init int init_posix_cpu_timers(void)
{
.clock_set = do_posix_clock_nosettime,
.timer_create = process_cpu_timer_create,
.nsleep = process_cpu_nsleep,
+ .nsleep_restart = process_cpu_nsleep_restart,
};
struct k_clock thread = {
.clock_getres = thread_cpu_clock_getres,
.clock_set = do_posix_clock_nosettime,
.timer_create = thread_cpu_timer_create,
.nsleep = thread_cpu_nsleep,
+ .nsleep_restart = thread_cpu_nsleep_restart,
};
register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
git.samba.org / sfrench / cifs-2.6.git / blobdiff