Merge remote-tracking branch 'airlied/drm-fixes' into drm-intel-next-queued

Back-merge from drm-fixes into drm-intel-next to sort out two things:

- interlaced support: -fixes contains a bugfix to correctly clear
  interlaced configuration bits in case the bios sets up an interlaced
  mode and we want to set up the progressive mode (current kernels
  don't support interlaced). The actual feature work to support
  interlaced depends upon (and conflicts with) this bugfix.

- forcewake voodoo to workaround missed IRQ issues: -fixes only enabled
  this for ivybridge, but some recent bug reports indicate that we
  need this on Sandybridge, too. But in a slightly different flavour
  and with other fixes and reworks on top. Additionally there are some
  forcewake cleanup patches heading to -next that would conflict with
  currrent -fixes.

Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 104 insertions, 99 deletions

diff --git a/kernel/freezer.c b/kernel/freezer.c
index 7be56c53439..9815b8d1eed 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -9,101 +9,114 @@
 #include <linux/export.h>
 #include <linux/syscalls.h>
 #include <linux/freezer.h>
+#include <linux/kthread.h>
 
-/*
- * freezing is complete, mark current process as frozen
+/* total number of freezing conditions in effect */
+atomic_t system_freezing_cnt = ATOMIC_INIT(0);
+EXPORT_SYMBOL(system_freezing_cnt);
+
+/* indicate whether PM freezing is in effect, protected by pm_mutex */
+bool pm_freezing;
+bool pm_nosig_freezing;
+
+/* protects freezing and frozen transitions */
+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
+ * 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.
  */
-static inline void frozen_process(void)
+bool freezing_slow_path(struct task_struct *p)
 {
-	if (!unlikely(current->flags & PF_NOFREEZE)) {
-		current->flags |= PF_FROZEN;
-		smp_wmb();
-	}
-	clear_freeze_flag(current);
+	if (p->flags & PF_NOFREEZE)
+		return false;
+
+	if (pm_nosig_freezing || cgroup_freezing(p))
+		return true;
+
+	if (pm_freezing && !(p->flags & PF_KTHREAD))
+		return true;
+
+	return false;
 }
+EXPORT_SYMBOL(freezing_slow_path);
 
 /* Refrigerator is place where frozen processes are stored :-). */
-void refrigerator(void)
+bool __refrigerator(bool check_kthr_stop)
 {
 	/* Hmm, should we be allowed to suspend when there are realtime
 	   processes around? */
-	long save;
+	bool was_frozen = false;
+	long save = current->state;
 
-	task_lock(current);
-	if (freezing(current)) {
-		frozen_process();
-		task_unlock(current);
-	} else {
-		task_unlock(current);
-		return;
-	}
-	save = current->state;
 	pr_debug("%s entered refrigerator\n", current->comm);
 
-	spin_lock_irq(&current->sighand->siglock);
-	recalc_sigpending(); /* We sent fake signal, clean it up */
-	spin_unlock_irq(&current->sighand->siglock);
-
-	/* prevent accounting of that task to load */
-	current->flags |= PF_FREEZING;
-
 	for (;;) {
 		set_current_state(TASK_UNINTERRUPTIBLE);
-		if (!frozen(current))
+
+		spin_lock_irq(&freezer_lock);
+		current->flags |= PF_FROZEN;
+		if (!freezing(current) ||
+		    (check_kthr_stop && kthread_should_stop()))
+			current->flags &= ~PF_FROZEN;
+		spin_unlock_irq(&freezer_lock);
+
+		if (!(current->flags & PF_FROZEN))
 			break;
+		was_frozen = true;
 		schedule();
 	}
 
-	/* Remove the accounting blocker */
-	current->flags &= ~PF_FREEZING;
-
 	pr_debug("%s left refrigerator\n", current->comm);
-	__set_current_state(save);
+
+	/*
+	 * 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);
+EXPORT_SYMBOL(__refrigerator);
 
 static void fake_signal_wake_up(struct task_struct *p)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&p->sighand->siglock, flags);
-	signal_wake_up(p, 0);
-	spin_unlock_irqrestore(&p->sighand->siglock, flags);
+	if (lock_task_sighand(p, &flags)) {
+		signal_wake_up(p, 0);
+		unlock_task_sighand(p, &flags);
+	}
 }
 
 /**
- *	freeze_task - send a freeze request to given task
- *	@p: task to send the request to
- *	@sig_only: if set, the request will only be sent if the task has the
- *		PF_FREEZER_NOSIG flag unset
- *	Return value: 'false', if @sig_only is set and the task has
- *		PF_FREEZER_NOSIG set or the task is frozen, 'true', otherwise
+ * freeze_task - send a freeze request to given task
+ * @p: task to send the request to
+ *
+ * If @p is freezing, the freeze request is sent by setting %TIF_FREEZE
+ * flag and either sending a fake signal to it or waking it up, depending
+ * on whether it has %PF_FREEZER_NOSIG set.
  *
- *	The freeze request is sent by setting the tasks's TIF_FREEZE flag and
- *	either sending a fake signal to it or waking it up, depending on whether
- *	or not it has PF_FREEZER_NOSIG set.  If @sig_only is set and the task
- *	has PF_FREEZER_NOSIG set (ie. it is a typical kernel thread), its
- *	TIF_FREEZE flag will not be set.
+ * RETURNS:
+ * %false, if @p is not freezing or already frozen; %true, otherwise
  */
-bool freeze_task(struct task_struct *p, bool sig_only)
+bool freeze_task(struct task_struct *p)
 {
-	/*
-	 * We first check if the task is freezing and next if it has already
-	 * been frozen to avoid the race with frozen_process() which first marks
-	 * the task as frozen and next clears its TIF_FREEZE.
-	 */
-	if (!freezing(p)) {
-		smp_rmb();
-		if (frozen(p))
-			return false;
-
-		if (!sig_only || should_send_signal(p))
-			set_freeze_flag(p);
-		else
-			return false;
+	unsigned long flags;
+
+	spin_lock_irqsave(&freezer_lock, flags);
+	if (!freezing(p) || frozen(p)) {
+		spin_unlock_irqrestore(&freezer_lock, flags);
+		return false;
 	}
 
-	if (should_send_signal(p)) {
+	if (!(p->flags & PF_KTHREAD)) {
 		fake_signal_wake_up(p);
 		/*
 		 * fake_signal_wake_up() goes through p's scheduler
@@ -111,56 +124,48 @@ bool freeze_task(struct task_struct *p, bool sig_only)
 		 * TASK_RUNNING transition can't race with task state
 		 * testing in try_to_freeze_tasks().
 		 */
-	} else if (sig_only) {
-		return false;
 	} else {
 		wake_up_state(p, TASK_INTERRUPTIBLE);
 	}
 
+	spin_unlock_irqrestore(&freezer_lock, flags);
 	return true;
 }
 
-void cancel_freezing(struct task_struct *p)
+void __thaw_task(struct task_struct *p)
 {
 	unsigned long flags;
 
-	if (freezing(p)) {
-		pr_debug("  clean up: %s\n", p->comm);
-		clear_freeze_flag(p);
-		spin_lock_irqsave(&p->sighand->siglock, flags);
-		recalc_sigpending_and_wake(p);
-		spin_unlock_irqrestore(&p->sighand->siglock, flags);
-	}
-}
-
-static int __thaw_process(struct task_struct *p)
-{
-	if (frozen(p)) {
-		p->flags &= ~PF_FROZEN;
-		return 1;
-	}
-	clear_freeze_flag(p);
-	return 0;
+	/*
+	 * Clear freezing and kick @p if FROZEN.  Clearing is guaranteed to
+	 * be visible to @p as waking up implies wmb.  Waking up inside
+	 * freezer_lock also prevents wakeups from leaking outside
+	 * refrigerator.
+	 */
+	spin_lock_irqsave(&freezer_lock, flags);
+	if (frozen(p))
+		wake_up_process(p);
+	spin_unlock_irqrestore(&freezer_lock, flags);
 }
 
-/*
- * Wake up a frozen process
+/**
+ * set_freezable - make %current freezable
  *
- * task_lock() is needed to prevent the race with refrigerator() which may
- * occur if the freezing of tasks fails.  Namely, without the lock, if the
- * freezing of tasks failed, thaw_tasks() might have run before a task in
- * refrigerator() could call frozen_process(), in which case the task would be
- * frozen and no one would thaw it.
+ * Mark %current freezable and enter refrigerator if necessary.
  */
-int thaw_process(struct task_struct *p)
+bool set_freezable(void)
 {
-	task_lock(p);
-	if (__thaw_process(p) == 1) {
-		task_unlock(p);
-		wake_up_process(p);
-		return 1;
-	}
-	task_unlock(p);
-	return 0;
+	might_sleep();
+
+	/*
+	 * Modify flags while holding freezer_lock.  This ensures the
+	 * freezer notices that we aren't frozen yet or the freezing
+	 * condition is visible to try_to_freeze() below.
+	 */
+	spin_lock_irq(&freezer_lock);
+	current->flags &= ~PF_NOFREEZE;
+	spin_unlock_irq(&freezer_lock);
+
+	return try_to_freeze();
 }
-EXPORT_SYMBOL(thaw_process);
+EXPORT_SYMBOL(set_freezable);