/* // Code not shown here decreases the current process's
* linux/kernel/sched.c // counter once every tick (10ms on a PC). When it reaches
* // 0, the procedure schedule() in this file is invoked to
* Kernel scheduler and related syscalls // choose the next process to run. This choice may also
* // happen earlier if the current process needs to wait
* Copyright (C) 1991, 1992 Linus Torvalds // for something, or if a non-runnable process becomes
* // runnable. (The decision to reschedule immediately in
* 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and // the latter case is made by code in reschedule_idle().)
* make semaphores SMP safe
* 1998-11-19 Implemented schedule_timeout() and related stuff
* by Andrea Arcangeli
* 1998-12-28 Implemented better SMP scheduling by Ingo Molnar
*/
/*
* 'sched.c' is the main kernel file. It contains scheduling primitives
* (sleep_on, wakeup, schedule etc) as well as a number of simple system
* call functions (type getpid()), which just extract a field from
* current-task
*/
#include <linux/config.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
extern void timer_bh(void);
extern void tqueue_bh(void);
extern void immediate_bh(void);
/*
* scheduler variables
*/
unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
extern void mem_use(void);
/*
* Scheduling quanta.
*
* NOTE! The unix "nice" value influences how long a process
* gets. The nice value ranges from -20 to +19, where a -20
* is a "high-priority" task, and a "+10" is a low-priority
* task.
*
* We want the time-slice to be around 50ms or so, so this
* calculation depends on the value of HZ.
*/
#if HZ < 200 // On a PC, HZ = 100, so the first version of TICK_SCALE
#define TICK_SCALE(x) ((x) >> 2) // is used. The C operation ">> 2" means to shift right
#elif HZ < 400 // two bit positions, i.e., take the quotient of division
#define TICK_SCALE(x) ((x) >> 1) // by 4.
#elif HZ < 800
#define TICK_SCALE(x) (x)
#elif HZ < 1600
#define TICK_SCALE(x) ((x) << 1)
#else
#define TICK_SCALE(x) ((x) << 2)
#endif
#define NICE_TO_TICKS(nice) (TICK_SCALE(20-(nice))+1) // So a process gets 1 extra tick per 4 niceness points.
/*
* Init task must be ok at boot for the ix86 as we will check its signals
* via the SMP irq return path.
*/
struct task_struct * init_tasks[NR_CPUS] = {&init_task, };
/*
* The tasklist_lock protects the linked list of processes.
*
* The scheduler lock is protecting against multiple entry
* into the scheduling code, and doesn't need to worry
* about interrupts (because interrupts cannot call the
* scheduler).
*
* The run-queue lock locks the parts that actually access
* and change the run-queues, and have to be interrupt-safe.
*/
spinlock_t runqueue_lock __cacheline_aligned = SPIN_LOCK_UNLOCKED; /* second */
rwlock_t tasklist_lock __cacheline_aligned = RW_LOCK_UNLOCKED; /* third */
static LIST_HEAD(runqueue_head);
/*
* We align per-CPU scheduling data on cacheline boundaries,
* to prevent cacheline ping-pong.
*/
static union {
struct schedule_data {
struct task_struct * curr;
cycles_t last_schedule;
} schedule_data;
char __pad [SMP_CACHE_BYTES];
} aligned_data [NR_CPUS] __cacheline_aligned = { {{&init_task,0}}};
#define cpu_curr(cpu) aligned_data[(cpu)].schedule_data.curr
#define last_schedule(cpu) aligned_data[(cpu)].schedule_data.last_schedule
struct kernel_stat kstat;
#ifdef CONFIG_SMP
#define idle_task(cpu) (init_tasks[cpu_number_map(cpu)])
#define can_schedule(p,cpu) ((!(p)->has_cpu) && \
((p)->cpus_allowed & (1 << cpu)))
#else
#define idle_task(cpu) (&init_task)
#define can_schedule(p,cpu) (1)
#endif
void scheduling_functions_start_here(void) { }
/*
* This is the function that decides how desirable a process is..
* You can weigh different processes against each other depending
* on what CPU they've run on lately etc to try to handle cache
* and TLB miss penalties.
*
* Return values:
* -1000: never select this
* 0: out of time, recalculate counters (but it might still be
* selected)
* +ve: "goodness" value (the larger, the better)
* +1000: realtime process, select this.
*/
static inline int goodness(struct task_struct * p, int this_cpu, struct mm_struct *this_mm)
{
int weight;
/*
* Realtime process, select the first one on the
* runqueue (taking priorities within processes
* into account).
*/
if (p->policy != SCHED_OTHER) {
weight = 1000 + p->rt_priority;
goto out;
}
/*
* Give the process a first-approximation goodness value
* according to the number of clock-ticks it has left.
*
* Don't do any other calculations if the time slice is
* over..
*/
weight = p->counter; // This is one of the two normal components of the goodness:
if (!weight) // how many ticks are left in the counter.
goto out;
#ifdef CONFIG_SMP // This block (until #endif) can be ignored since we don't
/* Give a largish advantage to the same processor... */ // care about SMP systems.
/* (this is equivalent to penalizing other processors) */
if (p->processor == this_cpu)
weight += PROC_CHANGE_PENALTY;
#endif
/* .. and a slight advantage to the current MM */ // Normally this just favors the current process; it also
if (p->mm == this_mm || !p->mm) // favors any other process sharing the same memory
weight += 1; // nmapping, but that is irrelevant for our experiments.
weight += 20 - p->nice; // This is the other normal component of the goodness:
// the process's niceness (subtracted from 20 so higher
out: // priority = numerically higher).
return weight;
}
/*
* subtle. We want to discard a yielded process only if it's being
* considered for a reschedule. Wakeup-time 'queries' of the scheduling
* state do not count. Another optimization we do: sched_yield()-ed
* processes are runnable (and thus will be considered for scheduling)
* right when they are calling schedule(). So the only place we need
* to care about SCHED_YIELD is when we calculate the previous process'
* goodness ...
*/
static inline int prev_goodness(struct task_struct * p, int this_cpu, struct mm_struct *this_mm)
{
if (p->policy & SCHED_YIELD) {
p->policy &= ~SCHED_YIELD;
return 0;
}
return goodness(p, this_cpu, this_mm);
}
/*
* the 'goodness value' of replacing a process on a given CPU.
* positive value means 'replace', zero or negative means 'dont'.
*/
static inline int preemption_goodness(struct task_struct * prev, struct task_struct * p, int cpu)
{
return goodness(p, cpu, prev->active_mm) - goodness(prev, cpu, prev->active_mm);
}
/*
* This is ugly, but reschedule_idle() is very timing-critical.
* We enter with the runqueue spinlock held, but we might end
* up unlocking it early, so the caller must not unlock the
* runqueue, it's always done by reschedule_idle().
*
* This function must be inline as anything that saves and restores
* flags has to do so within the same register window on sparc (Anton)
*/
static inline void reschedule_idle(struct task_struct * p, unsigned long flags)
{
#ifdef CONFIG_SMP // The huge block until #else is irrelevant for us, since
int this_cpu = smp_processor_id(); // we are only using uniprocessor systems.
struct task_struct *tsk, *target_tsk;
int cpu, best_cpu, i, max_prio;
cycles_t oldest_idle;
/*
* shortcut if the woken up task's last CPU is
* idle now.
*/
best_cpu = p->processor;
if (can_schedule(p, best_cpu)) {
tsk = idle_task(best_cpu);
if (cpu_curr(best_cpu) == tsk)
goto send_now_idle;
/*
* Maybe this process has enough priority to preempt
* its preferred CPU. (this is a shortcut):
*/
tsk = cpu_curr(best_cpu);
if (preemption_goodness(tsk, p, best_cpu) > 0)
goto preempt_now;
}
/*
* We know that the preferred CPU has a cache-affine current
* process, lets try to find a new idle CPU for the woken-up
* process. Select the least recently active idle CPU. (that
* one will have the least active cache context.) Also find
* the executing process which has the least priority.
*/
oldest_idle = (cycles_t) -1;
target_tsk = NULL;
max_prio = 1;
for (i = 0; i < smp_num_cpus; i++) {
cpu = cpu_logical_map(i);
if (!can_schedule(p, cpu))
continue;
tsk = cpu_curr(cpu);
/*
* We use the first available idle CPU. This creates
* a priority list between idle CPUs, but this is not
* a problem.
*/
if (tsk == idle_task(cpu)) {
if (last_schedule(cpu) < oldest_idle) {
oldest_idle = last_schedule(cpu);
target_tsk = tsk;
}
} else {
if (oldest_idle == -1ULL) {
int prio = preemption_goodness(tsk, p, cpu);
if (prio > max_prio) {
max_prio = prio;
target_tsk = tsk;
}
}
}
}
tsk = target_tsk;
if (tsk) {
if (oldest_idle != -1ULL)
goto send_now_idle;
goto preempt_now;
}
spin_unlock_irqrestore(&runqueue_lock, flags);
return;
send_now_idle:
/*
* If need_resched == -1 then we can skip sending the IPI
* altogether, tsk->need_resched is actively watched by the
* idle thread.
*/
if ((tsk->processor != current->processor) && !tsk->need_resched)
smp_send_reschedule(tsk->processor);
tsk->need_resched = 1;
spin_unlock_irqrestore(&runqueue_lock, flags);
return;
preempt_now:
tsk->need_resched = 1;
spin_unlock_irqrestore(&runqueue_lock, flags);
/*
* the APIC stuff can go outside of the lock because
* it uses no task information, only CPU#.
*/
if (tsk->processor != this_cpu)
smp_send_reschedule(tsk->processor);
return;
#else /* UP */
int this_cpu = smp_processor_id(); // This is done when a processs (p) becomes runnable.
struct task_struct *tsk;
tsk = cpu_curr(this_cpu);
if (preemption_goodness(tsk, p, this_cpu) > 1) // Is the newly runanble process enough bettter than the
tsk->need_resched = 1; // currently running process to be worth immediately
spin_unlock_irqrestore(&runqueue_lock, flags); // rescheduling, rather than waiting? Note that even
#endif // if the answer is yes, the same process could get
} // chosen to run again (or the new one, or any other).
/*
* Careful! // This comment is obsolete.
*
* This has to add the process to the _beginning_ of the
* run-queue, not the end. See the comment about "This is
* subtle" in the scheduler proper..
*/
static inline void add_to_runqueue(struct task_struct * p)
{
list_add(&p->run_list, &runqueue_head); // To see which end of the queue this is adding to, compare
nr_running++; // it with the next two procedures.
}
static inline void move_last_runqueue(struct task_struct * p)
{
list_del(&p->run_list);
list_add_tail(&p->run_list, &runqueue_head);
}
static inline void move_first_runqueue(struct task_struct * p)
{
list_del(&p->run_list);
list_add(&p->run_list, &runqueue_head);
}
/*
* Wake up a process. Put it on the run-queue if it's not
* already there. The "current" process is always on the
* run-queue (except when the actual re-schedule is in
* progress), and as such you're allowed to do the simpler
* "current->state = TASK_RUNNING" to mark yourself runnable
* without the overhead of this.
*/
inline void wake_up_process(struct task_struct * p)
{
unsigned long flags;
/*
* We want the common case fall through straight, thus the goto.
*/
spin_lock_irqsave(&runqueue_lock, flags);
p->state = TASK_RUNNING;
if (task_on_runqueue(p))
goto out;
add_to_runqueue(p);
reschedule_idle(p, flags); // spin_unlocks runqueue
return;
out:
spin_unlock_irqrestore(&runqueue_lock, flags);
}
static inline void wake_up_process_synchronous(struct task_struct * p)
{
unsigned long flags;
/*
* We want the common case fall through straight, thus the goto.
*/
spin_lock_irqsave(&runqueue_lock, flags);
p->state = TASK_RUNNING;
if (task_on_runqueue(p))
goto out;
add_to_runqueue(p);
out:
spin_unlock_irqrestore(&runqueue_lock, flags);
}
static void process_timeout(unsigned long __data)
{
struct task_struct * p = (struct task_struct *) __data;
wake_up_process(p);
}
signed long schedule_timeout(signed long timeout)
{
struct timer_list timer;
unsigned long expire;
switch (timeout)
{
case MAX_SCHEDULE_TIMEOUT:
/*
* These two special cases are useful to be comfortable
* in the caller. Nothing more. We could take
* MAX_SCHEDULE_TIMEOUT from one of the negative value
* but I' d like to return a valid offset (>=0) to allow
* the caller to do everything it want with the retval.
*/
schedule();
goto out;
default:
/*
* Another bit of PARANOID. Note that the retval will be
* 0 since no piece of kernel is supposed to do a check
* for a negative retval of schedule_timeout() (since it
* should never happens anyway). You just have the printk()
* that will tell you if something is gone wrong and where.
*/
if (timeout < 0)
{
printk(KERN_ERR "schedule_timeout: wrong timeout "
"value %lx from %p\n", timeout,
__builtin_return_address(0));
current->state = TASK_RUNNING;
goto out;
}
}
expire = timeout + jiffies;
init_timer(&timer);
timer.expires = expire;
timer.data = (unsigned long) current;
timer.function = process_timeout;
add_timer(&timer);
schedule();
del_timer_sync(&timer);
timeout = expire - jiffies;
out:
return timeout < 0 ? 0 : timeout;
}
/*
* schedule_tail() is getting called from the fork return path. This
* cleans up all remaining scheduler things, without impacting the
* common case.
*/
static inline void __schedule_tail(struct task_struct *prev)
{
#ifdef CONFIG_SMP
if ((prev->state == TASK_RUNNING) &&
(prev != idle_task(smp_processor_id()))) {
unsigned long flags;
spin_lock_irqsave(&runqueue_lock, flags);
prev->has_cpu = 0;
reschedule_idle(prev, flags); // spin_unlocks runqueue
} else {
wmb();
prev->has_cpu = 0;
}
#endif /* CONFIG_SMP */
}
void schedule_tail(struct task_struct *prev)
{
__schedule_tail(prev);
}
/*
* 'schedule()' is the scheduler function. It's a very simple and nice
* scheduler: it's not perfect, but certainly works for most things.
*
* The goto is "interesting".
*
* NOTE!! Task 0 is the 'idle' task, which gets called when no other
* tasks can run. It can not be killed, and it cannot sleep. The 'state'
* information in task[0] is never used.
*/
asmlinkage void schedule(void)
{
struct schedule_data * sched_data; // You can ignore everything until the comment that says
struct task_struct *prev, *next, *p; // "this is the scheduler proper".
struct list_head *tmp;
int this_cpu, c;
if (!current->active_mm) BUG();
if (tq_scheduler)
goto handle_tq_scheduler;
tq_scheduler_back:
prev = current;
this_cpu = prev->processor;
if (in_interrupt())
goto scheduling_in_interrupt;
release_kernel_lock(prev, this_cpu);
/* Do "administrative" work here while we don't hold any locks */
if (softirq_active(this_cpu) & softirq_mask(this_cpu))
goto handle_softirq;
handle_softirq_back:
/*
* 'sched_data' is protected by the fact that we can run
* only one process per CPU.
*/
sched_data = & aligned_data[this_cpu].schedule_data;
spin_lock_irq(&runqueue_lock);
/* move an exhausted RR process to be last.. */
if (prev->policy == SCHED_RR)
goto move_rr_last;
move_rr_back:
switch (prev->state & ~TASK_EXCLUSIVE) {
case TASK_INTERRUPTIBLE:
if (signal_pending(prev)) {
prev->state = TASK_RUNNING;
break;
}
default:
del_from_runqueue(prev);
case TASK_RUNNING:
}
prev->need_resched = 0;
/*
* this is the scheduler proper: // "next" is the next process to run, "c" is its goodness
*/ // These are used in a "king of the hill" fashion, keeping
// track of the best choice found so far.
repeat_schedule:
/* // If the current task is no longer runnable, we'll take a
* Default process to select.. // so-called idle task as the initial king (best so far).
*/ // The idle task does no useful work, so we want it to
next = idle_task(this_cpu); // win only if there are no other competitors; hence we
c = -1000; // give it a lousy score of -1000; anybody will beat it.
if (prev->state == TASK_RUNNING) // If on the other hand the current (previous) task is still
goto still_running; // runnable, go to code that initializes differently.
still_running_back:
list_for_each(tmp, &runqueue_head) {
p = list_entry(tmp, struct task_struct, run_list);
if (can_schedule(p, this_cpu)) {
int weight = goodness(p, this_cpu, prev->active_mm);
if (weight > c) // Update the best found so far. Note what happens if there
c = weight, next = p; // is a tie.
}
}
/* Do we need to re-calculate counters? */
if (!c) // If all runnable processes' counters are 0, charge the
goto recalculate; // counters back up (and repeat the scheduling loop).
/*
* from this point on nothing can prevent us from
* switching to the next task, save this fact in
* sched_data.
*/
sched_data->curr = next;
#ifdef CONFIG_SMP
next->has_cpu = 1;
next->processor = this_cpu;
#endif
spin_unlock_irq(&runqueue_lock);
if (prev == next)
goto same_process;
#ifdef CONFIG_SMP
/*
* maintain the per-process 'average timeslice' value.
* (this has to be recalculated even if we reschedule to
* the same process) Currently this is only used on SMP,
* and it's approximate, so we do not have to maintain
* it while holding the runqueue spinlock.
*/
{
cycles_t t, this_slice;
t = get_cycles();
this_slice = t - sched_data->last_schedule;
sched_data->last_schedule = t;
}
/*
* We drop the scheduler lock early (it's a global spinlock),
* thus we have to lock the previous process from getting
* rescheduled during switch_to().
*/
#endif /* CONFIG_SMP */
kstat.context_swtch++;
/*
* there are 3 processes which are affected by a context switch:
*
* prev == .... ==> (last => next)
*
* It's the 'much more previous' 'prev' that is on next's stack,
* but prev is set to (the just run) 'last' process by switch_to().
* This might sound slightly confusing but makes tons of sense.
*/
prepare_to_switch();
{
struct mm_struct *mm = next->mm;
struct mm_struct *oldmm = prev->active_mm;
if (!mm) {
if (next->active_mm) BUG();
next->active_mm = oldmm;
atomic_inc(&oldmm->mm_count);
enter_lazy_tlb(oldmm, next, this_cpu);
} else {
if (next->active_mm != mm) BUG();
switch_mm(oldmm, mm, next, this_cpu);
}
if (!prev->mm) {
prev->active_mm = NULL;
mmdrop(oldmm);
}
}
/*
* This just switches the register state and the
* stack.
*/
switch_to(prev, next, prev);
__schedule_tail(prev);
same_process:
reacquire_kernel_lock(current);
return;
recalculate: // Charge counters back up -- for *all* processes, not just
{ // the runnable ones (which all reached 0).
struct task_struct *p;
spin_unlock_irq(&runqueue_lock);
read_lock(&tasklist_lock);
for_each_task(p)
p->counter = (p->counter >> 1) + NICE_TO_TICKS(p->nice); // Note that if the counter isn't 0, half of the old value
read_unlock(&tasklist_lock); // is retained (because >> 1 is shift by 1 bit, i.e.,
spin_lock_irq(&runqueue_lock); // take the quotient by 2).
}
goto repeat_schedule;
still_running:
c = prev_goodness(prev, this_cpu, prev->active_mm); // Initial "king" (best so far) if current process is
next = prev; // runnable is that current (i.e., previous) process.
goto still_running_back; // For our purposes, prev_goodness is the same as
// goodness.
handle_softirq:
do_softirq();
goto handle_softirq_back;
handle_tq_scheduler:
/*
* do not run the task queue with disabled interrupts,
* cli() wouldn't work on SMP
*/
sti();
run_task_queue(&tq_scheduler);
goto tq_scheduler_back;
move_rr_last:
if (!prev->counter) {
prev->counter = NICE_TO_TICKS(prev->nice);
move_last_runqueue(prev);
}
goto move_rr_back;
scheduling_in_interrupt:
printk("Scheduling in interrupt\n");
BUG();
return;
}
static inline void __wake_up_common (wait_queue_head_t *q, unsigned int mode,
const int sync)
{
struct list_head *tmp, *head;
struct task_struct *p, *best_exclusive;
unsigned long flags;
int best_cpu, irq;
if (!q)
goto out;
best_cpu = smp_processor_id();
irq = in_interrupt();
best_exclusive = NULL;
wq_write_lock_irqsave(&q->lock, flags);
#if WAITQUEUE_DEBUG
CHECK_MAGIC_WQHEAD(q);
#endif
head = &q->task_list;
#if WAITQUEUE_DEBUG
if (!head->next || !head->prev)
WQ_BUG();
#endif
tmp = head->next;
while (tmp != head) {
unsigned int state;
wait_queue_t *curr = list_entry(tmp, wait_queue_t, task_list);
tmp = tmp->next;
#if WAITQUEUE_DEBUG
CHECK_MAGIC(curr->__magic);
#endif
p = curr->task;
state = p->state;
if (state & (mode & ~TASK_EXCLUSIVE)) {
#if WAITQUEUE_DEBUG
curr->__waker = (long)__builtin_return_address(0);
#endif
/*
* If waking up from an interrupt context then
* prefer processes which are affine to this
* CPU.
*/
if (irq && (state & mode & TASK_EXCLUSIVE)) {
if (!best_exclusive)
best_exclusive = p;
else if ((p->processor == best_cpu) &&
(best_exclusive->processor != best_cpu))
best_exclusive = p;
} else {
if (sync)
wake_up_process_synchronous(p);
else
wake_up_process(p);
if (state & mode & TASK_EXCLUSIVE)
break;
}
}
}
if (best_exclusive)
best_exclusive->state = TASK_RUNNING;
wq_write_unlock_irqrestore(&q->lock, flags);
if (best_exclusive) {
if (sync)
wake_up_process_synchronous(best_exclusive);
else
wake_up_process(best_exclusive);
}
out:
return;
}
void __wake_up(wait_queue_head_t *q, unsigned int mode)
{
__wake_up_common(q, mode, 0);
}
void __wake_up_sync(wait_queue_head_t *q, unsigned int mode)
{
__wake_up_common(q, mode, 1);
}
#define SLEEP_ON_VAR \
unsigned long flags; \
wait_queue_t wait; \
init_waitqueue_entry(&wait, current);
#define SLEEP_ON_HEAD \
wq_write_lock_irqsave(&q->lock,flags); \
__add_wait_queue(q, &wait); \
wq_write_unlock(&q->lock);
#define SLEEP_ON_TAIL \
wq_write_lock_irq(&q->lock); \
__remove_wait_queue(q, &wait); \
wq_write_unlock_irqrestore(&q->lock,flags);
void interruptible_sleep_on(wait_queue_head_t *q)
{
SLEEP_ON_VAR
current->state = TASK_INTERRUPTIBLE;
SLEEP_ON_HEAD
schedule();
SLEEP_ON_TAIL
}
long interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
{
SLEEP_ON_VAR
current->state = TASK_INTERRUPTIBLE;
SLEEP_ON_HEAD
timeout = schedule_timeout(timeout);
SLEEP_ON_TAIL
return timeout;
}
void sleep_on(wait_queue_head_t *q)
{
SLEEP_ON_VAR
current->state = TASK_UNINTERRUPTIBLE;
SLEEP_ON_HEAD
schedule();
SLEEP_ON_TAIL
}
long sleep_on_timeout(wait_queue_head_t *q, long timeout)
{
SLEEP_ON_VAR
current->state = TASK_UNINTERRUPTIBLE;
SLEEP_ON_HEAD
timeout = schedule_timeout(timeout);
SLEEP_ON_TAIL
return timeout;
}
void scheduling_functions_end_here(void) { }
#ifndef __alpha__
/*
* This has been replaced by sys_setpriority. Maybe it should be
* moved into the arch dependent tree for those ports that require
* it for backward compatibility?
*/
asmlinkage long sys_nice(int increment)
{
long newprio;
/*
* Setpriority might change our priority at the same moment.
* We don't have to worry. Conceptually one call occurs first
* and we have a single winner.
*/
if (increment < 0) {
if (!capable(CAP_SYS_NICE))
return -EPERM;
if (increment < -40)
increment = -40;
}
if (increment > 40)
increment = 40;
newprio = current->nice + increment;
if (newprio < -20)
newprio = -20;
if (newprio > 19)
newprio = 19;
current->nice = newprio;
return 0;
}
#endif
static inline struct task_struct *find_process_by_pid(pid_t pid)
{
struct task_struct *tsk = current;
if (pid)
tsk = find_task_by_pid(pid);
return tsk;
}
static int setscheduler(pid_t pid, int policy,
struct sched_param *param)
{
struct sched_param lp;
struct task_struct *p;
int retval;
retval = -EINVAL;
if (!param || pid < 0)
goto out_nounlock;
retval = -EFAULT;
if (copy_from_user(&lp, param, sizeof(struct sched_param)))
goto out_nounlock;
/*
* We play safe to avoid deadlocks.
*/
spin_lock_irq(&runqueue_lock);
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
retval = -ESRCH;
if (!p)
goto out_unlock;
if (policy < 0)
policy = p->policy;
else {
retval = -EINVAL;
if (policy != SCHED_FIFO && policy != SCHED_RR &&
policy != SCHED_OTHER)
goto out_unlock;
}
/*
* Valid priorities for SCHED_FIFO and SCHED_RR are 1..99, valid
* priority for SCHED_OTHER is 0.
*/
retval = -EINVAL;
if (lp.sched_priority < 0 || lp.sched_priority > 99)
goto out_unlock;
if ((policy == SCHED_OTHER) != (lp.sched_priority == 0))
goto out_unlock;
retval = -EPERM;
if ((policy == SCHED_FIFO || policy == SCHED_RR) &&
!capable(CAP_SYS_NICE))
goto out_unlock;
if ((current->euid != p->euid) && (current->euid != p->uid) &&
!capable(CAP_SYS_NICE))
goto out_unlock;
retval = 0;
p->policy = policy;
p->rt_priority = lp.sched_priority;
if (task_on_runqueue(p))
move_first_runqueue(p);
current->need_resched = 1;
out_unlock:
read_unlock(&tasklist_lock);
spin_unlock_irq(&runqueue_lock);
out_nounlock:
return retval;
}
asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
struct sched_param *param)
{
return setscheduler(pid, policy, param);
}
asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param *param)
{
return setscheduler(pid, -1, param);
}
asmlinkage long sys_sched_getscheduler(pid_t pid)
{
struct task_struct *p;
int retval;
retval = -EINVAL;
if (pid < 0)
goto out_nounlock;
retval = -ESRCH;
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
if (p)
retval = p->policy & ~SCHED_YIELD;
read_unlock(&tasklist_lock);
out_nounlock:
return retval;
}
asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param *param)
{
struct task_struct *p;
struct sched_param lp;
int retval;
retval = -EINVAL;
if (!param || pid < 0)
goto out_nounlock;
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
retval = -ESRCH;
if (!p)
goto out_unlock;
lp.sched_priority = p->rt_priority;
read_unlock(&tasklist_lock);
/*
* This one might sleep, we cannot do it with a spinlock held ...
*/
retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
out_nounlock:
return retval;
out_unlock:
read_unlock(&tasklist_lock);
return retval;
}
asmlinkage long sys_sched_yield(void)
{
spin_lock_irq(&runqueue_lock);
if (current->policy == SCHED_OTHER)
current->policy |= SCHED_YIELD;
current->need_resched = 1;
move_last_runqueue(current);
spin_unlock_irq(&runqueue_lock);
return 0;
}
asmlinkage long sys_sched_get_priority_max(int policy)
{
int ret = -EINVAL;
switch (policy) {
case SCHED_FIFO:
case SCHED_RR:
ret = 99;
break;
case SCHED_OTHER:
ret = 0;
break;
}
return ret;
}
asmlinkage long sys_sched_get_priority_min(int policy)
{
int ret = -EINVAL;
switch (policy) {
case SCHED_FIFO:
case SCHED_RR:
ret = 1;
break;
case SCHED_OTHER:
ret = 0;
}
return ret;
}
asmlinkage long sys_sched_rr_get_interval(pid_t pid, struct timespec *interval)
{
struct timespec t;
struct task_struct *p;
int retval = -EINVAL;
if (pid < 0)
goto out_nounlock;
retval = -ESRCH;
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
if (p)
jiffies_to_timespec(p->policy & SCHED_FIFO ? 0 : NICE_TO_TICKS(p->nice),
&t);
read_unlock(&tasklist_lock);
if (p)
retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
out_nounlock:
return retval;
}
static void show_task(struct task_struct * p)
{
unsigned long free = 0;
int state;
static const char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
printk("%-8s ", p->comm);
state = p->state ? ffz(~p->state) + 1 : 0;
if (((unsigned) state) < sizeof(stat_nam)/sizeof(char *))
printk(stat_nam[state]);
else
printk(" ");
#if (BITS_PER_LONG == 32)
if (p == current)
printk(" current ");
else
printk(" %08lX ", thread_saved_pc(&p->thread));
#else
if (p == current)
printk(" current task ");
else
printk(" %016lx ", thread_saved_pc(&p->thread));
#endif
{
unsigned long * n = (unsigned long *) (p+1);
while (!*n)
n++;
free = (unsigned long) n - (unsigned long)(p+1);
}
printk("%5lu %5d %6d ", free, p->pid, p->p_pptr->pid);
if (p->p_cptr)
printk("%5d ", p->p_cptr->pid);
else
printk(" ");
if (!p->mm)
printk(" (L-TLB) ");
else
printk(" (NOTLB) ");
if (p->p_ysptr)
printk("%7d", p->p_ysptr->pid);
else
printk(" ");
if (p->p_osptr)
printk(" %5d\n", p->p_osptr->pid);
else
printk("\n");
{
struct signal_queue *q;
char s[sizeof(sigset_t)*2+1], b[sizeof(sigset_t)*2+1];
render_sigset_t(&p->signal, s);
render_sigset_t(&p->blocked, b);
printk(" sig: %d %s %s :", signal_pending(p), s, b);
for (q = p->sigqueue; q ; q = q->next)
printk(" %d", q->info.si_signo);
printk(" X\n");
}
}
char * render_sigset_t(sigset_t *set, char *buffer)
{
int i = _NSIG, x;
do {
i -= 4, x = 0;
if (sigismember(set, i+1)) x |= 1;
if (sigismember(set, i+2)) x |= 2;
if (sigismember(set, i+3)) x |= 4;
if (sigismember(set, i+4)) x |= 8;
*buffer++ = (x < 10 ? '0' : 'a' - 10) + x;
} while (i >= 4);
*buffer = 0;
return buffer;
}
void show_state(void)
{
struct task_struct *p;
#if (BITS_PER_LONG == 32)
printk("\n"
" free sibling\n");
printk(" task PC stack pid father child younger older\n");
#else
printk("\n"
" free sibling\n");
printk(" task PC stack pid father child younger older\n");
#endif
read_lock(&tasklist_lock);
for_each_task(p)
show_task(p);
read_unlock(&tasklist_lock);
}
/*
* Put all the gunge required to become a kernel thread without
* attached user resources in one place where it belongs.
*/
void daemonize(void)
{
struct fs_struct *fs;
/*
* If we were started as result of loading a module, close all of the
* user space pages. We don't need them, and if we didn't close them
* they would be locked into memory.
*/
exit_mm(current);
current->session = 1;
current->pgrp = 1;
/* Become as one with the init task */
exit_fs(current); /* current->fs->count--; */
fs = init_task.fs;
current->fs = fs;
atomic_inc(&fs->count);
}
void __init init_idle(void)
{
struct schedule_data * sched_data;
sched_data = &aligned_data[smp_processor_id()].schedule_data;
if (current != &init_task && task_on_runqueue(current)) {
printk("UGH! (%d:%d) was on the runqueue, removing.\n",
smp_processor_id(), current->pid);
del_from_runqueue(current);
}
sched_data->curr = current;
sched_data->last_schedule = get_cycles();
}
extern void init_timervecs (void);
void __init sched_init(void)
{
/*
* We have to do a little magic to get the first
* process right in SMP mode.
*/
int cpu = smp_processor_id();
int nr;
init_task.processor = cpu;
for(nr = 0; nr < PIDHASH_SZ; nr++)
pidhash[nr] = NULL;
init_timervecs();
init_bh(TIMER_BH, timer_bh);
init_bh(TQUEUE_BH, tqueue_bh);
init_bh(IMMEDIATE_BH, immediate_bh);
/*
* The boot idle thread does lazy MMU switching as well:
*/
atomic_inc(&init_mm.mm_count);
enter_lazy_tlb(&init_mm, current, cpu);
}