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[PATCH] Cleanup patch for process freezing

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>
This commit is contained in:
Christoph Lameter 2005-06-24 23:13:50 -07:00 committed by Linus Torvalds
parent b3e112bcc1
commit 3e1d1d28d9
47 changed files with 126 additions and 113 deletions

View File

@ -12,8 +12,7 @@ refrigerator. Code to do this looks like this:
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()

View File

@ -164,8 +164,7 @@ place where the thread is safe to be frozen (no kernel semaphores
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.

View File

@ -536,10 +536,8 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
if (!user_mode(regs))
return 1;
if (current->flags & PF_FREEZE) {
refrigerator(0);
if (try_to_freeze())
goto no_signal;
}
if (!oldset)
oldset = &current->blocked;

View File

@ -517,10 +517,8 @@ asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset)
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;

View File

@ -573,7 +573,7 @@ static int balanced_irq(void *unused)
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();

View File

@ -608,10 +608,8 @@ int fastcall do_signal(struct pt_regs *regs, sigset_t *oldset)
if (!user_mode(regs))
return 1;
if (current->flags & PF_FREEZE) {
refrigerator(0);
if (try_to_freeze)
goto no_signal;
}
if (!oldset)
oldset = &current->blocked;

View File

@ -371,10 +371,8 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
if (!user_mode(regs))
return 1;
if (current->flags & PF_FREEZE) {
refrigerator(0);
if (try_to_freeze())
goto no_signal;
}
if (!oldset)
oldset = &current->blocked;

View File

@ -705,8 +705,7 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
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;

View File

@ -425,7 +425,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
if (!user_mode(regs))
return 1;
if (try_to_freeze(0))
if (try_to_freeze())
goto no_signal;
if (!oldset)

View File

@ -1251,8 +1251,7 @@ static int kcdrwd(void *foobar)
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)

View File

@ -1041,10 +1041,8 @@ static int hpsbpkt_thread(void *__hi)
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;
}

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@ -1510,7 +1510,7 @@ static int nodemgr_host_thread(void *__hi)
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;

View File

@ -439,7 +439,7 @@ static int gameport_thread(void *nothing)
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");

View File

@ -344,7 +344,7 @@ static int serio_thread(void *nothing)
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");

View File

@ -328,9 +328,7 @@ static int monitor_task(void *arg)
struct thermostat* th = arg;
while(!kthread_should_stop()) {
if (current->flags & PF_FREEZE)
refrigerator(PF_FREEZE);
try_to_freeze();
msleep_interruptible(2000);
#ifndef DEBUG

View File

@ -2976,8 +2976,7 @@ static int md_thread(void * arg)
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);

View File

@ -391,8 +391,7 @@ static int dvb_frontend_thread(void *data)
break;
}
if (current->flags & PF_FREEZE)
refrigerator(PF_FREEZE);
try_to_freeze();
if (down_interruptible(&fepriv->sem))
break;

View File

@ -750,8 +750,7 @@ static int msp34xx_sleep(struct msp3400c *msp, int timeout)
#endif
}
}
if (current->flags & PF_FREEZE)
refrigerator(PF_FREEZE);
try_to_freeze();
remove_wait_queue(&msp->wq, &wait);
return msp->restart;
}

View File

@ -62,8 +62,7 @@ static int videobuf_dvb_thread(void *data)
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)

View File

@ -1606,7 +1606,7 @@ static int rtl8139_thread (void *data)
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)) {

View File

@ -135,8 +135,7 @@ static int irda_thread(void *startup)
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();
}

View File

@ -763,7 +763,7 @@ static int stir_transmit_thread(void *arg)
{
#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
@ -771,7 +771,7 @@ static int stir_transmit_thread(void *arg)
write_reg(stir, REG_CTRL1, CTRL1_TXPWD|CTRL1_RXPWD);
refrigerator(PF_FREEZE);
refrigerator();
if (change_speed(stir, stir->speed))
break;

View File

@ -2918,7 +2918,7 @@ static int airo_thread(void *data) {
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;

View File

@ -718,7 +718,7 @@ static int pccardd(void *__skt)
}
schedule();
try_to_freeze(PF_FREEZE);
try_to_freeze();
if (!skt->thread)
break;

View File

@ -182,7 +182,7 @@ static int pnp_dock_thread(void * unused)
msleep_interruptible(2000);
if(signal_pending(current)) {
if (try_to_freeze(PF_FREEZE))
if (try_to_freeze())
continue;
break;
}

View File

@ -2808,7 +2808,7 @@ static int hub_thread(void *__unused)
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);

View File

@ -1554,8 +1554,7 @@ static int sleep_thread(struct fsg_dev *fsg)
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);
}

View File

@ -847,10 +847,8 @@ retry:
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 */

View File

@ -646,7 +646,7 @@ static int w1_control(void *data)
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))
@ -725,7 +725,7 @@ int w1_process(void *data)
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))

View File

@ -116,7 +116,7 @@ static int kafsasyncd(void *arg)
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();

View File

@ -91,7 +91,7 @@ static int kafstimod(void *arg)
complete_and_exit(&kafstimod_dead, 0);
}
try_to_freeze(PF_FREEZE);
try_to_freeze();
/* discard pending signals */
afs_discard_my_signals();

View File

@ -167,7 +167,7 @@ loop:
}
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
@ -175,7 +175,7 @@ loop:
*/
jbd_debug(1, "Now suspending kjournald\n");
spin_unlock(&journal->j_state_lock);
refrigerator(PF_FREEZE);
refrigerator();
spin_lock(&journal->j_state_lock);
} else {
/*

View File

@ -2359,9 +2359,9 @@ int jfsIOWait(void *arg)
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);

View File

@ -2788,9 +2788,9 @@ int jfs_lazycommit(void *arg)
/* 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);
@ -2987,9 +2987,9 @@ int jfs_sync(void *arg)
/* 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);

View File

@ -313,7 +313,7 @@ static int nlm_wait_on_grace(wait_queue_head_t *queue)
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;
}

View File

@ -1771,9 +1771,9 @@ xfsbufd(
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;
}

View File

@ -483,7 +483,7 @@ xfssyncd(
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;

View File

@ -1245,33 +1245,78 @@ extern void normalize_rt_tasks(void);
#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__ */

View File

@ -32,7 +32,7 @@ static inline int freezeable(struct task_struct * p)
}
/* 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? */
@ -41,14 +41,13 @@ void refrigerator(unsigned long flag)
current->state = TASK_UNINTERRUPTIBLE;
pr_debug("%s entered refrigerator\n", current->comm);
printk("=");
current->flags &= ~PF_FREEZE;
frozen_process(current);
spin_lock_irq(&current->sighand->siglock);
recalc_sigpending(); /* We sent fake signal, clean it up */
spin_unlock_irq(&current->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;
@ -57,10 +56,10 @@ void refrigerator(unsigned long flag)
/* 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 {
@ -70,14 +69,12 @@ int freeze_processes(void)
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);
@ -91,7 +88,7 @@ int freeze_processes(void)
return todo;
}
} while(todo);
printk( "|\n" );
BUG_ON(in_atomic());
return 0;
@ -106,10 +103,7 @@ void thaw_processes(void)
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);

View File

@ -4174,8 +4174,7 @@ static int migration_thread(void * data)
struct list_head *head;
migration_req_t *req;
if (current->flags & PF_FREEZE)
refrigerator(PF_FREEZE);
try_to_freeze();
spin_lock_irq(&rq->lock);

View File

@ -213,7 +213,7 @@ static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
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);
@ -2231,8 +2231,7 @@ sys_rt_sigtimedwait(const sigset_t __user *uthese,
current->state = TASK_INTERRUPTIBLE;
timeout = schedule_timeout(timeout);
if (current->flags & PF_FREEZE)
refrigerator(PF_FREEZE);
try_to_freeze();
spin_lock_irq(&current->sighand->siglock);
sig = dequeue_signal(current, &these, &info);
current->blocked = current->real_blocked;

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@ -105,7 +105,7 @@ static int __pdflush(struct pdflush_work *my_work)
spin_unlock_irq(&pdflush_lock);
schedule();
if (try_to_freeze(PF_FREEZE)) {
if (try_to_freeze()) {
spin_lock_irq(&pdflush_lock);
continue;
}

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@ -1216,8 +1216,8 @@ static int kswapd(void *p)
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;

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@ -138,7 +138,7 @@ static int rxrpc_krxiod(void *arg)
_debug("### End Work");
try_to_freeze(PF_FREEZE);
try_to_freeze();
/* discard pending signals */
rxrpc_discard_my_signals();

View File

@ -107,7 +107,7 @@ static int rxrpc_krxsecd(void *arg)
_debug("### End Inbound Calls");
try_to_freeze(PF_FREEZE);
try_to_freeze();
/* discard pending signals */
rxrpc_discard_my_signals();

View File

@ -90,7 +90,7 @@ static int krxtimod(void *arg)
complete_and_exit(&krxtimod_dead, 0);
}
try_to_freeze(PF_FREEZE);
try_to_freeze();
/* discard pending signals */
rxrpc_discard_my_signals();

View File

@ -1185,8 +1185,8 @@ svc_recv(struct svc_serv *serv, struct svc_rqst *rqstp, long timeout)
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;
@ -1227,7 +1227,7 @@ svc_recv(struct svc_serv *serv, struct svc_rqst *rqstp, long timeout)
schedule_timeout(timeout);
try_to_freeze(PF_FREEZE);
try_to_freeze();
spin_lock_bh(&serv->sv_lock);
remove_wait_queue(&rqstp->rq_wait, &wait);