1. Establish a simple API for process freezing defined in linux/include/sched.h:
frozen(process) Check for frozen process
freezing(process) Check if a process is being frozen
freeze(process) Tell a process to freeze (go to refrigerator)
thaw_process(process) Restart process
frozen_process(process) Process is frozen now
2. Remove all references to PF_FREEZE and PF_FROZEN from all
kernel sources except sched.h
3. Fix numerous locations where try_to_freeze is manually done by a driver
4. Remove the argument that is no longer necessary from two function calls.
5. Some whitespace cleanup
6. Clear potential race in refrigerator (provides an open window of PF_FREEZE
cleared before setting PF_FROZEN, recalc_sigpending does not check
PF_FROZEN).
This patch does not address the problem of freeze_processes() violating the rule
that a task may only modify its own flags by setting PF_FREEZE. This is not clean
in an SMP environment. freeze(process) is therefore not SMP safe!
Signed-off-by: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
do {
hub_events();
wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list));
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
} while (!signal_pending(current));
from drivers/usb/core/hub.c::hub_thread()
should be held at that point and it must be safe to sleep there), and
add:
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
If the thread is needed for writing the image to storage, you should
instead set the PF_NOFREEZE process flag when creating the thread.
if (!user_mode(regs))
return 1;
- if (current->flags & PF_FREEZE) {
- refrigerator(0);
+ if (try_to_freeze())
goto no_signal;
- }
if (!oldset)
oldset = ¤t->blocked;
if ((regs->ccr & 0x10))
return 1;
- if (current->flags & PF_FREEZE) {
- refrigerator(0);
+ if (try_to_freeze())
goto no_signal;
- }
current->thread.esp0 = (unsigned long) regs;
for ( ; ; ) {
set_current_state(TASK_INTERRUPTIBLE);
time_remaining = schedule_timeout(time_remaining);
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
if (time_after(jiffies,
prev_balance_time+balanced_irq_interval)) {
do_irq_balance();
if (!user_mode(regs))
return 1;
- if (current->flags & PF_FREEZE) {
- refrigerator(0);
+ if (try_to_freeze)
goto no_signal;
- }
if (!oldset)
oldset = ¤t->blocked;
if (!user_mode(regs))
return 1;
- if (current->flags & PF_FREEZE) {
- refrigerator(0);
+ if (try_to_freeze())
goto no_signal;
- }
if (!oldset)
oldset = ¤t->blocked;
unsigned long frame, newsp;
int signr, ret;
- if (current->flags & PF_FREEZE) {
- refrigerator(PF_FREEZE);
+ if (try_to_freeze()) {
signr = 0;
if (!signal_pending(current))
goto no_signal;
if (!user_mode(regs))
return 1;
- if (try_to_freeze(0))
+ if (try_to_freeze())
goto no_signal;
if (!oldset)
VPRINTK("kcdrwd: wake up\n");
/* make swsusp happy with our thread */
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
if (!pkt->sleep_time)
while (1) {
if (down_interruptible(&khpsbpkt_sig)) {
- if (current->flags & PF_FREEZE) {
- refrigerator(0);
+ if (try_to_freeze())
continue;
- }
printk("khpsbpkt: received unexpected signal?!\n" );
break;
}
if (down_interruptible(&hi->reset_sem) ||
down_interruptible(&nodemgr_serialize)) {
- if (try_to_freeze(PF_FREEZE))
+ if (try_to_freeze())
continue;
printk("NodeMgr: received unexpected signal?!\n" );
break;
do {
gameport_handle_events();
wait_event_interruptible(gameport_wait, !list_empty(&gameport_event_list));
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
} while (!signal_pending(current));
printk(KERN_DEBUG "gameport: kgameportd exiting\n");
do {
serio_handle_events();
wait_event_interruptible(serio_wait, !list_empty(&serio_event_list));
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
} while (!signal_pending(current));
printk(KERN_DEBUG "serio: kseriod exiting\n");
struct thermostat* th = arg;
while(!kthread_should_stop()) {
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
-
+ try_to_freeze();
msleep_interruptible(2000);
#ifndef DEBUG
wait_event_interruptible_timeout(thread->wqueue,
test_bit(THREAD_WAKEUP, &thread->flags),
thread->timeout);
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
clear_bit(THREAD_WAKEUP, &thread->flags);
break;
}
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
if (down_interruptible(&fepriv->sem))
break;
#endif
}
}
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
remove_wait_queue(&msp->wq, &wait);
return msp->restart;
}
break;
if (kthread_should_stop())
break;
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
/* feed buffer data to demux */
if (buf->state == STATE_DONE)
do {
timeout = interruptible_sleep_on_timeout (&tp->thr_wait, timeout);
/* make swsusp happy with our thread */
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
} while (!signal_pending (current) && (timeout > 0));
if (signal_pending (current)) {
remove_wait_queue(&irda_rq_queue.kick, &wait);
/* make swsusp happy with our thread */
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
run_irda_queue();
}
{
#ifdef CONFIG_PM
/* if suspending, then power off and wait */
- if (unlikely(current->flags & PF_FREEZE)) {
+ if (unlikely(freezing(current))) {
if (stir->receiving)
receive_stop(stir);
else
write_reg(stir, REG_CTRL1, CTRL1_TXPWD|CTRL1_RXPWD);
- refrigerator(PF_FREEZE);
+ refrigerator();
if (change_speed(stir, stir->speed))
break;
flush_signals(current);
/* make swsusp happy with our thread */
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
if (test_bit(JOB_DIE, &ai->flags))
break;
}
schedule();
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
if (!skt->thread)
break;
msleep_interruptible(2000);
if(signal_pending(current)) {
- if (try_to_freeze(PF_FREEZE))
+ if (try_to_freeze())
continue;
break;
}
do {
hub_events();
wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list));
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
} while (!signal_pending(current));
pr_debug ("%s: khubd exiting\n", usbcore_name);
rc = wait_event_interruptible(fsg->thread_wqh,
fsg->thread_wakeup_needed);
fsg->thread_wakeup_needed = 0;
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
return (rc ? -EINTR : 0);
}
wait_event_interruptible_timeout(us->delay_wait,
test_bit(US_FLIDX_DISCONNECTING, &us->flags),
delay_use * HZ);
- if (current->flags & PF_FREEZE) {
- refrigerator(PF_FREEZE);
+ if (try_to_freeze())
goto retry;
- }
}
/* If the device is still connected, perform the scanning */
while (!control_needs_exit || have_to_wait) {
have_to_wait = 0;
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
msleep_interruptible(w1_timeout * 1000);
if (signal_pending(current))
allow_signal(SIGTERM);
while (!test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
msleep_interruptible(w1_timeout * 1000);
if (signal_pending(current))
remove_wait_queue(&kafsasyncd_sleepq, &myself);
set_current_state(TASK_RUNNING);
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
/* discard pending signals */
afs_discard_my_signals();
complete_and_exit(&kafstimod_dead, 0);
}
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
/* discard pending signals */
afs_discard_my_signals();
}
wake_up(&journal->j_wait_done_commit);
- if (current->flags & PF_FREEZE) {
+ if (freezing(current)) {
/*
* The simpler the better. Flushing journal isn't a
* good idea, because that depends on threads that may
*/
jbd_debug(1, "Now suspending kjournald\n");
spin_unlock(&journal->j_state_lock);
- refrigerator(PF_FREEZE);
+ refrigerator();
spin_lock(&journal->j_state_lock);
} else {
/*
lbmStartIO(bp);
spin_lock_irq(&log_redrive_lock);
}
- if (current->flags & PF_FREEZE) {
+ if (freezing(current)) {
spin_unlock_irq(&log_redrive_lock);
- refrigerator(PF_FREEZE);
+ refrigerator();
} else {
add_wait_queue(&jfs_IO_thread_wait, &wq);
set_current_state(TASK_INTERRUPTIBLE);
/* In case a wakeup came while all threads were active */
jfs_commit_thread_waking = 0;
- if (current->flags & PF_FREEZE) {
+ if (freezing(current)) {
LAZY_UNLOCK(flags);
- refrigerator(PF_FREEZE);
+ refrigerator();
} else {
DECLARE_WAITQUEUE(wq, current);
/* Add anon_list2 back to anon_list */
list_splice_init(&TxAnchor.anon_list2, &TxAnchor.anon_list);
- if (current->flags & PF_FREEZE) {
+ if (freezing(current)) {
TXN_UNLOCK();
- refrigerator(PF_FREEZE);
+ refrigerator();
} else {
DECLARE_WAITQUEUE(wq, current);
prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
if (!signalled ()) {
schedule_timeout(NLMCLNT_GRACE_WAIT);
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
if (!signalled ())
status = 0;
}
INIT_LIST_HEAD(&tmp);
do {
- if (unlikely(current->flags & PF_FREEZE)) {
+ if (unlikely(freezing(current))) {
xfsbufd_force_sleep = 1;
- refrigerator(PF_FREEZE);
+ refrigerator();
} else {
xfsbufd_force_sleep = 0;
}
set_current_state(TASK_INTERRUPTIBLE);
timeleft = schedule_timeout(timeleft);
/* swsusp */
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
if (vfsp->vfs_flag & VFS_UMOUNT)
break;
#endif
-/* try_to_freeze
- *
- * Checks whether we need to enter the refrigerator
- * and returns 1 if we did so.
- */
#ifdef CONFIG_PM
-extern void refrigerator(unsigned long);
+/*
+ * Check if a process has been frozen
+ */
+static inline int frozen(struct task_struct *p)
+{
+ return p->flags & PF_FROZEN;
+}
+
+/*
+ * Check if there is a request to freeze a process
+ */
+static inline int freezing(struct task_struct *p)
+{
+ return p->flags & PF_FREEZE;
+}
+
+/*
+ * Request that a process be frozen
+ * FIXME: SMP problem. We may not modify other process' flags!
+ */
+static inline void freeze(struct task_struct *p)
+{
+ p->flags |= PF_FREEZE;
+}
+
+/*
+ * Wake up a frozen process
+ */
+static inline int thaw_process(struct task_struct *p)
+{
+ if (frozen(p)) {
+ p->flags &= ~PF_FROZEN;
+ wake_up_process(p);
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * freezing is complete, mark process as frozen
+ */
+static inline void frozen_process(struct task_struct *p)
+{
+ p->flags = (p->flags & ~PF_FREEZE) | PF_FROZEN;
+}
+
+extern void refrigerator(void);
extern int freeze_processes(void);
extern void thaw_processes(void);
-static inline int try_to_freeze(unsigned long refrigerator_flags)
+static inline int try_to_freeze(void)
{
- if (unlikely(current->flags & PF_FREEZE)) {
- refrigerator(refrigerator_flags);
+ if (freezing(current)) {
+ refrigerator();
return 1;
} else
return 0;
}
#else
-static inline void refrigerator(unsigned long flag) {}
+static inline int frozen(struct task_struct *p) { return 0; }
+static inline int freezing(struct task_struct *p) { return 0; }
+static inline void freeze(struct task_struct *p) { BUG(); }
+static inline int thaw_process(struct task_struct *p) { return 1; }
+static inline void frozen_process(struct task_struct *p) { BUG(); }
+
+static inline void refrigerator(void) {}
static inline int freeze_processes(void) { BUG(); return 0; }
static inline void thaw_processes(void) {}
-static inline int try_to_freeze(unsigned long refrigerator_flags)
-{
- return 0;
-}
+static inline int try_to_freeze(void) { return 0; }
+
#endif /* CONFIG_PM */
#endif /* __KERNEL__ */
}
/* Refrigerator is place where frozen processes are stored :-). */
-void refrigerator(unsigned long flag)
+void refrigerator(void)
{
/* Hmm, should we be allowed to suspend when there are realtime
processes around? */
current->state = TASK_UNINTERRUPTIBLE;
pr_debug("%s entered refrigerator\n", current->comm);
printk("=");
- current->flags &= ~PF_FREEZE;
+ frozen_process(current);
spin_lock_irq(¤t->sighand->siglock);
recalc_sigpending(); /* We sent fake signal, clean it up */
spin_unlock_irq(¤t->sighand->siglock);
- current->flags |= PF_FROZEN;
- while (current->flags & PF_FROZEN)
+ while (frozen(current))
schedule();
pr_debug("%s left refrigerator\n", current->comm);
current->state = save;
/* 0 = success, else # of processes that we failed to stop */
int freeze_processes(void)
{
- int todo;
- unsigned long start_time;
+ int todo;
+ unsigned long start_time;
struct task_struct *g, *p;
-
+
printk( "Stopping tasks: " );
start_time = jiffies;
do {
unsigned long flags;
if (!freezeable(p))
continue;
- if ((p->flags & PF_FROZEN) ||
+ if ((frozen(p)) ||
(p->state == TASK_TRACED) ||
(p->state == TASK_STOPPED))
continue;
- /* FIXME: smp problem here: we may not access other process' flags
- without locking */
- p->flags |= PF_FREEZE;
+ freeze(p);
spin_lock_irqsave(&p->sighand->siglock, flags);
signal_wake_up(p, 0);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
return todo;
}
} while(todo);
-
+
printk( "|\n" );
BUG_ON(in_atomic());
return 0;
do_each_thread(g, p) {
if (!freezeable(p))
continue;
- if (p->flags & PF_FROZEN) {
- p->flags &= ~PF_FROZEN;
- wake_up_process(p);
- } else
+ if (!thaw_process(p))
printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
} while_each_thread(g, p);
struct list_head *head;
migration_req_t *req;
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
spin_lock_irq(&rq->lock);
fastcall void recalc_sigpending_tsk(struct task_struct *t)
{
if (t->signal->group_stop_count > 0 ||
- (t->flags & PF_FREEZE) ||
+ (freezing(t)) ||
PENDING(&t->pending, &t->blocked) ||
PENDING(&t->signal->shared_pending, &t->blocked))
set_tsk_thread_flag(t, TIF_SIGPENDING);
current->state = TASK_INTERRUPTIBLE;
timeout = schedule_timeout(timeout);
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
spin_lock_irq(¤t->sighand->siglock);
sig = dequeue_signal(current, &these, &info);
current->blocked = current->real_blocked;
spin_unlock_irq(&pdflush_lock);
schedule();
- if (try_to_freeze(PF_FREEZE)) {
+ if (try_to_freeze()) {
spin_lock_irq(&pdflush_lock);
continue;
}
order = 0;
for ( ; ; ) {
unsigned long new_order;
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+
+ try_to_freeze();
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
new_order = pgdat->kswapd_max_order;
_debug("### End Work");
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
/* discard pending signals */
rxrpc_discard_my_signals();
_debug("### End Inbound Calls");
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
/* discard pending signals */
rxrpc_discard_my_signals();
complete_and_exit(&krxtimod_dead, 0);
}
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
/* discard pending signals */
rxrpc_discard_my_signals();
arg->page_len = (pages-2)*PAGE_SIZE;
arg->len = (pages-1)*PAGE_SIZE;
arg->tail[0].iov_len = 0;
-
- try_to_freeze(PF_FREEZE);
+
+ try_to_freeze();
if (signalled())
return -EINTR;
schedule_timeout(timeout);
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
spin_lock_bh(&serv->sv_lock);
remove_wait_queue(&rqstp->rq_wait, &wait);
projects / linux-2.6 / commitdiff