#ifdef CONFIG_SCHED_HRTICK
/*
* Use HR-timers to deliver accurate preemption points.
- *
- * Its all a bit involved since we cannot program an hrt while holding the
- * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
- * reschedule event.
- *
- * When we get rescheduled we reprogram the hrtick_timer outside of the
- * rq->lock.
*/
static void hrtick_clear(struct rq *rq)
}
#ifdef CONFIG_SMP
+
+static int __hrtick_restart(struct rq *rq)
+{
+ struct hrtimer *timer = &rq->hrtick_timer;
+ ktime_t time = hrtimer_get_softexpires(timer);
+
+ return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0);
+}
+
/*
* called from hardirq (IPI) context
*/
struct rq *rq = arg;
raw_spin_lock(&rq->lock);
- hrtimer_restart(&rq->hrtick_timer);
+ __hrtick_restart(rq);
rq->hrtick_csd_pending = 0;
raw_spin_unlock(&rq->lock);
}
hrtimer_set_expires(timer, time);
if (rq == this_rq()) {
- hrtimer_restart(timer);
+ __hrtick_restart(rq);
} else if (!rq->hrtick_csd_pending) {
__smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
rq->hrtick_csd_pending = 1;
/**
* task_curr - is this task currently executing on a CPU?
* @p: the task in question.
+ *
+ * Return: 1 if the task is currently executing. 0 otherwise.
*/
inline int task_curr(const struct task_struct *p)
{
* the simpler "current->state = TASK_RUNNING" to mark yourself
* runnable without the overhead of this.
*
- * Returns %true if @p was woken up, %false if it was already running
+ * Return: %true if @p was woken up, %false if it was already running.
* or @state didn't match @p's state.
*/
static int
unsigned long flags;
int cpu, success = 0;
- smp_wmb();
+ /*
+ * If we are going to wake up a thread waiting for CONDITION we
+ * need to ensure that CONDITION=1 done by the caller can not be
+ * reordered with p->state check below. This pairs with mb() in
+ * set_current_state() the waiting thread does.
+ */
+ smp_mb__before_spinlock();
raw_spin_lock_irqsave(&p->pi_lock, flags);
if (!(p->state & state))
goto out;
* @p: The process to be woken up.
*
* Attempt to wake up the nominated process and move it to the set of runnable
- * processes. Returns 1 if the process was woken up, 0 if it was already
- * running.
+ * processes.
+ *
+ * Return: 1 if the process was woken up, 0 if it was already running.
*
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
* This makes sure that uptime, CFS vruntime, load
* balancing, etc... continue to move forward, even
* with a very low granularity.
+ *
+ * Return: Maximum deferment in nanoseconds.
*/
u64 scheduler_tick_max_deferment(void)
{
if (sched_feat(HRTICK))
hrtick_clear(rq);
+ /*
+ * Make sure that signal_pending_state()->signal_pending() below
+ * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
+ * done by the caller to avoid the race with signal_wake_up().
+ */
+ smp_mb__before_spinlock();
raw_spin_lock_irq(&rq->lock);
switch_count = &prev->nivcsw;
* specified timeout to expire. The timeout is in jiffies. It is not
* interruptible.
*
- * The return value is 0 if timed out, and positive (at least 1, or number of
- * jiffies left till timeout) if completed.
+ * Return: 0 if timed out, and positive (at least 1, or number of jiffies left
+ * till timeout) if completed.
*/
unsigned long __sched
wait_for_completion_timeout(struct completion *x, unsigned long timeout)
* specified timeout to expire. The timeout is in jiffies. It is not
* interruptible. The caller is accounted as waiting for IO.
*
- * The return value is 0 if timed out, and positive (at least 1, or number of
- * jiffies left till timeout) if completed.
+ * Return: 0 if timed out, and positive (at least 1, or number of jiffies left
+ * till timeout) if completed.
*/
unsigned long __sched
wait_for_completion_io_timeout(struct completion *x, unsigned long timeout)
* This waits for completion of a specific task to be signaled. It is
* interruptible.
*
- * The return value is -ERESTARTSYS if interrupted, 0 if completed.
+ * Return: -ERESTARTSYS if interrupted, 0 if completed.
*/
int __sched wait_for_completion_interruptible(struct completion *x)
{
* This waits for either a completion of a specific task to be signaled or for a
* specified timeout to expire. It is interruptible. The timeout is in jiffies.
*
- * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
- * positive (at least 1, or number of jiffies left till timeout) if completed.
+ * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1,
+ * or number of jiffies left till timeout) if completed.
*/
long __sched
wait_for_completion_interruptible_timeout(struct completion *x,
* This waits to be signaled for completion of a specific task. It can be
* interrupted by a kill signal.
*
- * The return value is -ERESTARTSYS if interrupted, 0 if completed.
+ * Return: -ERESTARTSYS if interrupted, 0 if completed.
*/
int __sched wait_for_completion_killable(struct completion *x)
{
* signaled or for a specified timeout to expire. It can be
* interrupted by a kill signal. The timeout is in jiffies.
*
- * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
- * positive (at least 1, or number of jiffies left till timeout) if completed.
+ * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1,
+ * or number of jiffies left till timeout) if completed.
*/
long __sched
wait_for_completion_killable_timeout(struct completion *x,
* try_wait_for_completion - try to decrement a completion without blocking
* @x: completion structure
*
- * Returns: 0 if a decrement cannot be done without blocking
+ * Return: 0 if a decrement cannot be done without blocking
* 1 if a decrement succeeded.
*
* If a completion is being used as a counting completion,
* completion_done - Test to see if a completion has any waiters
* @x: completion structure
*
- * Returns: 0 if there are waiters (wait_for_completion() in progress)
+ * Return: 0 if there are waiters (wait_for_completion() in progress)
* 1 if there are no waiters.
*
*/
* task_prio - return the priority value of a given task.
* @p: the task in question.
*
- * This is the priority value as seen by users in /proc.
+ * Return: The priority value as seen by users in /proc.
* RT tasks are offset by -200. Normal tasks are centered
* around 0, value goes from -16 to +15.
*/
/**
* task_nice - return the nice value of a given task.
* @p: the task in question.
+ *
+ * Return: The nice value [ -20 ... 0 ... 19 ].
*/
int task_nice(const struct task_struct *p)
{
/**
* idle_cpu - is a given cpu idle currently?
* @cpu: the processor in question.
+ *
+ * Return: 1 if the CPU is currently idle. 0 otherwise.
*/
int idle_cpu(int cpu)
{
/**
* idle_task - return the idle task for a given cpu.
* @cpu: the processor in question.
+ *
+ * Return: The idle task for the cpu @cpu.
*/
struct task_struct *idle_task(int cpu)
{
/**
* find_process_by_pid - find a process with a matching PID value.
* @pid: the pid in question.
+ *
+ * The task of @pid, if found. %NULL otherwise.
*/
static struct task_struct *find_process_by_pid(pid_t pid)
{
* @policy: new policy.
* @param: structure containing the new RT priority.
*
+ * Return: 0 on success. An error code otherwise.
+ *
* NOTE that the task may be already dead.
*/
int sched_setscheduler(struct task_struct *p, int policy,
* current context has permission. For example, this is needed in
* stop_machine(): we create temporary high priority worker threads,
* but our caller might not have that capability.
+ *
+ * Return: 0 on success. An error code otherwise.
*/
int sched_setscheduler_nocheck(struct task_struct *p, int policy,
const struct sched_param *param)
* @pid: the pid in question.
* @policy: new policy.
* @param: structure containing the new RT priority.
+ *
+ * Return: 0 on success. An error code otherwise.
*/
SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
struct sched_param __user *, param)
* sys_sched_setparam - set/change the RT priority of a thread
* @pid: the pid in question.
* @param: structure containing the new RT priority.
+ *
+ * Return: 0 on success. An error code otherwise.
*/
SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
{
/**
* sys_sched_getscheduler - get the policy (scheduling class) of a thread
* @pid: the pid in question.
+ *
+ * Return: On success, the policy of the thread. Otherwise, a negative error
+ * code.
*/
SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
{
* sys_sched_getparam - get the RT priority of a thread
* @pid: the pid in question.
* @param: structure containing the RT priority.
+ *
+ * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
+ * code.
*/
SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
{
* @pid: pid of the process
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
* @user_mask_ptr: user-space pointer to the new cpu mask
+ *
+ * Return: 0 on success. An error code otherwise.
*/
SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
unsigned long __user *, user_mask_ptr)
* @pid: pid of the process
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
* @user_mask_ptr: user-space pointer to hold the current cpu mask
+ *
+ * Return: 0 on success. An error code otherwise.
*/
SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
unsigned long __user *, user_mask_ptr)
*
* This function yields the current CPU to other tasks. If there are no
* other threads running on this CPU then this function will return.
+ *
+ * Return: 0.
*/
SYSCALL_DEFINE0(sched_yield)
{
* It's the caller's job to ensure that the target task struct
* can't go away on us before we can do any checks.
*
- * Returns:
+ * Return:
* true (>0) if we indeed boosted the target task.
* false (0) if we failed to boost the target.
* -ESRCH if there's no task to yield to.
* sys_sched_get_priority_max - return maximum RT priority.
* @policy: scheduling class.
*
- * this syscall returns the maximum rt_priority that can be used
- * by a given scheduling class.
+ * Return: On success, this syscall returns the maximum
+ * rt_priority that can be used by a given scheduling class.
+ * On failure, a negative error code is returned.
*/
SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
{
* sys_sched_get_priority_min - return minimum RT priority.
* @policy: scheduling class.
*
- * this syscall returns the minimum rt_priority that can be used
- * by a given scheduling class.
+ * Return: On success, this syscall returns the minimum
+ * rt_priority that can be used by a given scheduling class.
+ * On failure, a negative error code is returned.
*/
SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
{
*
* this syscall writes the default timeslice value of a given process
* into the user-space timespec buffer. A value of '0' means infinity.
+ *
+ * Return: On success, 0 and the timeslice is in @interval. Otherwise,
+ * an error code.
*/
SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
struct timespec __user *, interval)
debug_show_all_locks();
}
-void __cpuinit init_idle_bootup_task(struct task_struct *idle)
+void init_idle_bootup_task(struct task_struct *idle)
{
idle->sched_class = &idle_sched_class;
}
* NOTE: this function does not set the idle thread's NEED_RESCHED
* flag, to make booting more robust.
*/
-void __cpuinit init_idle(struct task_struct *idle, int cpu)
+void init_idle(struct task_struct *idle, int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
* migration_call - callback that gets triggered when a CPU is added.
* Here we can start up the necessary migration thread for the new CPU.
*/
-static int __cpuinit
+static int
migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
int cpu = (long)hcpu;
* happens before everything else. This has to be lower priority than
* the notifier in the perf_event subsystem, though.
*/
-static struct notifier_block __cpuinitdata migration_notifier = {
+static struct notifier_block migration_notifier = {
.notifier_call = migration_call,
.priority = CPU_PRI_MIGRATION,
};
-static int __cpuinit sched_cpu_active(struct notifier_block *nfb,
+static int sched_cpu_active(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
switch (action & ~CPU_TASKS_FROZEN) {
}
}
-static int __cpuinit sched_cpu_inactive(struct notifier_block *nfb,
+static int sched_cpu_inactive(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
switch (action & ~CPU_TASKS_FROZEN) {
* @cpu: the processor in question.
*
* ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
+ *
+ * Return: The current task for @cpu.
*/
struct task_struct *curr_task(int cpu)
{
projects / linux-beck.git / blobdiff