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-rw-r--r--kernel/cgroup/legacy_freezer.c23
-rw-r--r--kernel/exit.c4
-rw-r--r--kernel/fork.c5
-rw-r--r--kernel/freezer.c133
-rw-r--r--kernel/futex/waitwake.c8
-rw-r--r--kernel/hung_task.c4
-rw-r--r--kernel/power/main.c6
-rw-r--r--kernel/power/process.c10
-rw-r--r--kernel/ptrace.c2
-rw-r--r--kernel/sched/core.c2
-rw-r--r--kernel/signal.c14
-rw-r--r--kernel/time/hrtimer.c4
-rw-r--r--kernel/umh.c20
13 files changed, 141 insertions, 94 deletions
diff --git a/kernel/cgroup/legacy_freezer.c b/kernel/cgroup/legacy_freezer.c
index 08236798d173..1b6b21851e9d 100644
--- a/kernel/cgroup/legacy_freezer.c
+++ b/kernel/cgroup/legacy_freezer.c
@@ -113,7 +113,7 @@ static int freezer_css_online(struct cgroup_subsys_state *css)
if (parent && (parent->state & CGROUP_FREEZING)) {
freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN;
- atomic_inc(&system_freezing_cnt);
+ static_branch_inc(&freezer_active);
}
mutex_unlock(&freezer_mutex);
@@ -134,7 +134,7 @@ static void freezer_css_offline(struct cgroup_subsys_state *css)
mutex_lock(&freezer_mutex);
if (freezer->state & CGROUP_FREEZING)
- atomic_dec(&system_freezing_cnt);
+ static_branch_dec(&freezer_active);
freezer->state = 0;
@@ -179,6 +179,7 @@ static void freezer_attach(struct cgroup_taskset *tset)
__thaw_task(task);
} else {
freeze_task(task);
+
/* clear FROZEN and propagate upwards */
while (freezer && (freezer->state & CGROUP_FROZEN)) {
freezer->state &= ~CGROUP_FROZEN;
@@ -271,16 +272,8 @@ static void update_if_frozen(struct cgroup_subsys_state *css)
css_task_iter_start(css, 0, &it);
while ((task = css_task_iter_next(&it))) {
- if (freezing(task)) {
- /*
- * freezer_should_skip() indicates that the task
- * should be skipped when determining freezing
- * completion. Consider it frozen in addition to
- * the usual frozen condition.
- */
- if (!frozen(task) && !freezer_should_skip(task))
- goto out_iter_end;
- }
+ if (freezing(task) && !frozen(task))
+ goto out_iter_end;
}
freezer->state |= CGROUP_FROZEN;
@@ -357,7 +350,7 @@ static void freezer_apply_state(struct freezer *freezer, bool freeze,
if (freeze) {
if (!(freezer->state & CGROUP_FREEZING))
- atomic_inc(&system_freezing_cnt);
+ static_branch_inc(&freezer_active);
freezer->state |= state;
freeze_cgroup(freezer);
} else {
@@ -366,9 +359,9 @@ static void freezer_apply_state(struct freezer *freezer, bool freeze,
freezer->state &= ~state;
if (!(freezer->state & CGROUP_FREEZING)) {
- if (was_freezing)
- atomic_dec(&system_freezing_cnt);
freezer->state &= ~CGROUP_FROZEN;
+ if (was_freezing)
+ static_branch_dec(&freezer_active);
unfreeze_cgroup(freezer);
}
}
diff --git a/kernel/exit.c b/kernel/exit.c
index 84021b24f79e..ba683f8d292a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -374,10 +374,10 @@ static void coredump_task_exit(struct task_struct *tsk)
complete(&core_state->startup);
for (;;) {
- set_current_state(TASK_UNINTERRUPTIBLE);
+ set_current_state(TASK_UNINTERRUPTIBLE|TASK_FREEZABLE);
if (!self.task) /* see coredump_finish() */
break;
- freezable_schedule();
+ schedule();
}
__set_current_state(TASK_RUNNING);
}
diff --git a/kernel/fork.c b/kernel/fork.c
index 90c85b17bf69..a1de2f5e305d 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1420,13 +1420,12 @@ static void complete_vfork_done(struct task_struct *tsk)
static int wait_for_vfork_done(struct task_struct *child,
struct completion *vfork)
{
+ unsigned int state = TASK_UNINTERRUPTIBLE|TASK_KILLABLE|TASK_FREEZABLE;
int killed;
- freezer_do_not_count();
cgroup_enter_frozen();
- killed = wait_for_completion_killable(vfork);
+ killed = wait_for_completion_state(vfork, state);
cgroup_leave_frozen(false);
- freezer_count();
if (killed) {
task_lock(child);
diff --git a/kernel/freezer.c b/kernel/freezer.c
index 45ab36ffd0e7..4fad0e6fca64 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -13,10 +13,11 @@
#include <linux/kthread.h>
/* total number of freezing conditions in effect */
-atomic_t system_freezing_cnt = ATOMIC_INIT(0);
-EXPORT_SYMBOL(system_freezing_cnt);
+DEFINE_STATIC_KEY_FALSE(freezer_active);
+EXPORT_SYMBOL(freezer_active);
-/* indicate whether PM freezing is in effect, protected by
+/*
+ * indicate whether PM freezing is in effect, protected by
* system_transition_mutex
*/
bool pm_freezing;
@@ -29,7 +30,7 @@ static DEFINE_SPINLOCK(freezer_lock);
* freezing_slow_path - slow path for testing whether a task needs to be frozen
* @p: task to be tested
*
- * This function is called by freezing() if system_freezing_cnt isn't zero
+ * This function is called by freezing() if freezer_active isn't zero
* and tests whether @p needs to enter and stay in frozen state. Can be
* called under any context. The freezers are responsible for ensuring the
* target tasks see the updated state.
@@ -52,41 +53,40 @@ bool freezing_slow_path(struct task_struct *p)
}
EXPORT_SYMBOL(freezing_slow_path);
+bool frozen(struct task_struct *p)
+{
+ return READ_ONCE(p->__state) & TASK_FROZEN;
+}
+
/* Refrigerator is place where frozen processes are stored :-). */
bool __refrigerator(bool check_kthr_stop)
{
- /* Hmm, should we be allowed to suspend when there are realtime
- processes around? */
+ unsigned int state = get_current_state();
bool was_frozen = false;
- unsigned int save = get_current_state();
pr_debug("%s entered refrigerator\n", current->comm);
+ WARN_ON_ONCE(state && !(state & TASK_NORMAL));
+
for (;;) {
- set_current_state(TASK_UNINTERRUPTIBLE);
+ bool freeze;
+
+ set_current_state(TASK_FROZEN);
spin_lock_irq(&freezer_lock);
- current->flags |= PF_FROZEN;
- if (!freezing(current) ||
- (check_kthr_stop && kthread_should_stop()))
- current->flags &= ~PF_FROZEN;
+ freeze = freezing(current) && !(check_kthr_stop && kthread_should_stop());
spin_unlock_irq(&freezer_lock);
- if (!(current->flags & PF_FROZEN))
+ if (!freeze)
break;
+
was_frozen = true;
schedule();
}
+ __set_current_state(TASK_RUNNING);
pr_debug("%s left refrigerator\n", current->comm);
- /*
- * Restore saved task state before returning. The mb'd version
- * needs to be used; otherwise, it might silently break
- * synchronization which depends on ordered task state change.
- */
- set_current_state(save);
-
return was_frozen;
}
EXPORT_SYMBOL(__refrigerator);
@@ -101,6 +101,44 @@ static void fake_signal_wake_up(struct task_struct *p)
}
}
+static int __set_task_frozen(struct task_struct *p, void *arg)
+{
+ unsigned int state = READ_ONCE(p->__state);
+
+ if (p->on_rq)
+ return 0;
+
+ if (p != current && task_curr(p))
+ return 0;
+
+ if (!(state & (TASK_FREEZABLE | __TASK_STOPPED | __TASK_TRACED)))
+ return 0;
+
+ /*
+ * Only TASK_NORMAL can be augmented with TASK_FREEZABLE, since they
+ * can suffer spurious wakeups.
+ */
+ if (state & TASK_FREEZABLE)
+ WARN_ON_ONCE(!(state & TASK_NORMAL));
+
+#ifdef CONFIG_LOCKDEP
+ /*
+ * It's dangerous to freeze with locks held; there be dragons there.
+ */
+ if (!(state & __TASK_FREEZABLE_UNSAFE))
+ WARN_ON_ONCE(debug_locks && p->lockdep_depth);
+#endif
+
+ WRITE_ONCE(p->__state, TASK_FROZEN);
+ return TASK_FROZEN;
+}
+
+static bool __freeze_task(struct task_struct *p)
+{
+ /* TASK_FREEZABLE|TASK_STOPPED|TASK_TRACED -> TASK_FROZEN */
+ return task_call_func(p, __set_task_frozen, NULL);
+}
+
/**
* freeze_task - send a freeze request to given task
* @p: task to send the request to
@@ -116,20 +154,8 @@ bool freeze_task(struct task_struct *p)
{
unsigned long flags;
- /*
- * This check can race with freezer_do_not_count, but worst case that
- * will result in an extra wakeup being sent to the task. It does not
- * race with freezer_count(), the barriers in freezer_count() and
- * freezer_should_skip() ensure that either freezer_count() sees
- * freezing == true in try_to_freeze() and freezes, or
- * freezer_should_skip() sees !PF_FREEZE_SKIP and freezes the task
- * normally.
- */
- if (freezer_should_skip(p))
- return false;
-
spin_lock_irqsave(&freezer_lock, flags);
- if (!freezing(p) || frozen(p)) {
+ if (!freezing(p) || frozen(p) || __freeze_task(p)) {
spin_unlock_irqrestore(&freezer_lock, flags);
return false;
}
@@ -137,19 +163,52 @@ bool freeze_task(struct task_struct *p)
if (!(p->flags & PF_KTHREAD))
fake_signal_wake_up(p);
else
- wake_up_state(p, TASK_INTERRUPTIBLE);
+ wake_up_state(p, TASK_NORMAL);
spin_unlock_irqrestore(&freezer_lock, flags);
return true;
}
+/*
+ * The special task states (TASK_STOPPED, TASK_TRACED) keep their canonical
+ * state in p->jobctl. If either of them got a wakeup that was missed because
+ * TASK_FROZEN, then their canonical state reflects that and the below will
+ * refuse to restore the special state and instead issue the wakeup.
+ */
+static int __set_task_special(struct task_struct *p, void *arg)
+{
+ unsigned int state = 0;
+
+ if (p->jobctl & JOBCTL_TRACED)
+ state = TASK_TRACED;
+
+ else if (p->jobctl & JOBCTL_STOPPED)
+ state = TASK_STOPPED;
+
+ if (state)
+ WRITE_ONCE(p->__state, state);
+
+ return state;
+}
+
void __thaw_task(struct task_struct *p)
{
- unsigned long flags;
+ unsigned long flags, flags2;
spin_lock_irqsave(&freezer_lock, flags);
- if (frozen(p))
- wake_up_process(p);
+ if (WARN_ON_ONCE(freezing(p)))
+ goto unlock;
+
+ if (lock_task_sighand(p, &flags2)) {
+ /* TASK_FROZEN -> TASK_{STOPPED,TRACED} */
+ bool ret = task_call_func(p, __set_task_special, NULL);
+ unlock_task_sighand(p, &flags2);
+ if (ret)
+ goto unlock;
+ }
+
+ wake_up_state(p, TASK_FROZEN);
+unlock:
spin_unlock_irqrestore(&freezer_lock, flags);
}
diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c
index 4ce0923f1ce3..ba01b9408203 100644
--- a/kernel/futex/waitwake.c
+++ b/kernel/futex/waitwake.c
@@ -334,7 +334,7 @@ void futex_wait_queue(struct futex_hash_bucket *hb, struct futex_q *q,
* futex_queue() calls spin_unlock() upon completion, both serializing
* access to the hash list and forcing another memory barrier.
*/
- set_current_state(TASK_INTERRUPTIBLE);
+ set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
futex_queue(q, hb);
/* Arm the timer */
@@ -352,7 +352,7 @@ void futex_wait_queue(struct futex_hash_bucket *hb, struct futex_q *q,
* is no timeout, or if it has yet to expire.
*/
if (!timeout || timeout->task)
- freezable_schedule();
+ schedule();
}
__set_current_state(TASK_RUNNING);
}
@@ -430,7 +430,7 @@ retry:
return ret;
}
- set_current_state(TASK_INTERRUPTIBLE);
+ set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
for (i = 0; i < count; i++) {
u32 __user *uaddr = (u32 __user *)(unsigned long)vs[i].w.uaddr;
@@ -504,7 +504,7 @@ static void futex_sleep_multiple(struct futex_vector *vs, unsigned int count,
return;
}
- freezable_schedule();
+ schedule();
}
/**
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index bb2354f73ded..f1321c03c32a 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -95,8 +95,8 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
* Ensure the task is not frozen.
* Also, skip vfork and any other user process that freezer should skip.
*/
- if (unlikely(t->flags & (PF_FROZEN | PF_FREEZER_SKIP)))
- return;
+ if (unlikely(READ_ONCE(t->__state) & (TASK_FREEZABLE | TASK_FROZEN)))
+ return;
/*
* When a freshly created task is scheduled once, changes its state to
diff --git a/kernel/power/main.c b/kernel/power/main.c
index dae3d17919e6..31ec4a9b9d70 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -24,7 +24,7 @@
unsigned int lock_system_sleep(void)
{
unsigned int flags = current->flags;
- current->flags |= PF_FREEZER_SKIP;
+ current->flags |= PF_NOFREEZE;
mutex_lock(&system_transition_mutex);
return flags;
}
@@ -48,8 +48,8 @@ void unlock_system_sleep(unsigned int flags)
* Which means, if we use try_to_freeze() here, it would make them
* enter the refrigerator, thus causing hibernation to lockup.
*/
- if (!(flags & PF_FREEZER_SKIP))
- current->flags &= ~PF_FREEZER_SKIP;
+ if (!(flags & PF_NOFREEZE))
+ current->flags &= ~PF_NOFREEZE;
mutex_unlock(&system_transition_mutex);
}
EXPORT_SYMBOL_GPL(unlock_system_sleep);
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 3068601e585a..ddd9988327fe 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -50,8 +50,7 @@ static int try_to_freeze_tasks(bool user_only)
if (p == current || !freeze_task(p))
continue;
- if (!freezer_should_skip(p))
- todo++;
+ todo++;
}
read_unlock(&tasklist_lock);
@@ -96,8 +95,7 @@ static int try_to_freeze_tasks(bool user_only)
if (!wakeup || pm_debug_messages_on) {
read_lock(&tasklist_lock);
for_each_process_thread(g, p) {
- if (p != current && !freezer_should_skip(p)
- && freezing(p) && !frozen(p))
+ if (p != current && freezing(p) && !frozen(p))
sched_show_task(p);
}
read_unlock(&tasklist_lock);
@@ -129,7 +127,7 @@ int freeze_processes(void)
current->flags |= PF_SUSPEND_TASK;
if (!pm_freezing)
- atomic_inc(&system_freezing_cnt);
+ static_branch_inc(&freezer_active);
pm_wakeup_clear(0);
pr_info("Freezing user space processes ... ");
@@ -190,7 +188,7 @@ void thaw_processes(void)
trace_suspend_resume(TPS("thaw_processes"), 0, true);
if (pm_freezing)
- atomic_dec(&system_freezing_cnt);
+ static_branch_dec(&freezer_active);
pm_freezing = false;
pm_nosig_freezing = false;
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 1893d909e45c..54482193e1ed 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -269,7 +269,7 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
read_unlock(&tasklist_lock);
if (!ret && !ignore_state &&
- WARN_ON_ONCE(!wait_task_inactive(child, __TASK_TRACED)))
+ WARN_ON_ONCE(!wait_task_inactive(child, __TASK_TRACED|TASK_FROZEN)))
ret = -ESRCH;
return ret;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ea26526b45bb..2b85d1b5fe0c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6428,7 +6428,7 @@ static void __sched notrace __schedule(unsigned int sched_mode)
prev->sched_contributes_to_load =
(prev_state & TASK_UNINTERRUPTIBLE) &&
!(prev_state & TASK_NOLOAD) &&
- !(prev->flags & PF_FROZEN);
+ !(prev_state & TASK_FROZEN);
if (prev->sched_contributes_to_load)
rq->nr_uninterruptible++;
diff --git a/kernel/signal.c b/kernel/signal.c
index 6f86fda5e432..c2e90d6ca0d1 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2304,7 +2304,7 @@ static int ptrace_stop(int exit_code, int why, unsigned long message,
read_unlock(&tasklist_lock);
cgroup_enter_frozen();
preempt_enable_no_resched();
- freezable_schedule();
+ schedule();
cgroup_leave_frozen(true);
/*
@@ -2473,7 +2473,7 @@ static bool do_signal_stop(int signr)
/* Now we don't run again until woken by SIGCONT or SIGKILL */
cgroup_enter_frozen();
- freezable_schedule();
+ schedule();
return true;
} else {
/*
@@ -2548,11 +2548,11 @@ static void do_freezer_trap(void)
* immediately (if there is a non-fatal signal pending), and
* put the task into sleep.
*/
- __set_current_state(TASK_INTERRUPTIBLE);
+ __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
clear_thread_flag(TIF_SIGPENDING);
spin_unlock_irq(&current->sighand->siglock);
cgroup_enter_frozen();
- freezable_schedule();
+ schedule();
}
static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
@@ -3600,9 +3600,9 @@ static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
recalc_sigpending();
spin_unlock_irq(&tsk->sighand->siglock);
- __set_current_state(TASK_INTERRUPTIBLE);
- ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
- HRTIMER_MODE_REL);
+ __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
+ ret = schedule_hrtimeout_range(to, tsk->timer_slack_ns,
+ HRTIMER_MODE_REL);
spin_lock_irq(&tsk->sighand->siglock);
__set_task_blocked(tsk, &tsk->real_blocked);
sigemptyset(&tsk->real_blocked);
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 23af5eca11b1..3ae661ab6260 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -2037,11 +2037,11 @@ static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mod
struct restart_block *restart;
do {
- set_current_state(TASK_INTERRUPTIBLE);
+ set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
hrtimer_sleeper_start_expires(t, mode);
if (likely(t->task))
- freezable_schedule();
+ schedule();
hrtimer_cancel(&t->timer);
mode = HRTIMER_MODE_ABS;
diff --git a/kernel/umh.c b/kernel/umh.c
index 8945eaf4c671..850631518665 100644
--- a/kernel/umh.c
+++ b/kernel/umh.c
@@ -404,6 +404,7 @@ EXPORT_SYMBOL(call_usermodehelper_setup);
*/
int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
{
+ unsigned int state = TASK_UNINTERRUPTIBLE;
DECLARE_COMPLETION_ONSTACK(done);
int retval = 0;
@@ -437,25 +438,22 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
if (wait == UMH_NO_WAIT) /* task has freed sub_info */
goto unlock;
+ if (wait & UMH_KILLABLE)
+ state |= TASK_KILLABLE;
+
if (wait & UMH_FREEZABLE)
- freezer_do_not_count();
+ state |= TASK_FREEZABLE;
- if (wait & UMH_KILLABLE) {
- retval = wait_for_completion_killable(&done);
- if (!retval)
- goto wait_done;
+ retval = wait_for_completion_state(&done, state);
+ if (!retval)
+ goto wait_done;
+ if (wait & UMH_KILLABLE) {
/* umh_complete() will see NULL and free sub_info */
if (xchg(&sub_info->complete, NULL))
goto unlock;
- /* fallthrough, umh_complete() was already called */
}
- wait_for_completion(&done);
-
- if (wait & UMH_FREEZABLE)
- freezer_count();
-
wait_done:
retval = sub_info->retval;
out:
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.