Fixed MTP to work with TWRP

kernel/power/process.c

@@ -0,0 +1,278 @@
+/*
+ * drivers/power/process.c - Functions for starting/stopping processes on 
+ *                           suspend transitions.
+ *
+ * Originally from swsusp.
+ */
+
+
+#undef DEBUG
+
+#include <linux/interrupt.h>
+#include <linux/oom.h>
+#include <linux/suspend.h>
+#include <linux/module.h>
+#include <linux/syscalls.h>
+#include <linux/freezer.h>
+#include <linux/delay.h>
+#include <linux/workqueue.h>
+#include <linux/kmod.h>
+#include <trace/events/power.h>
+#include <linux/wakeup_reason.h>
+
+/* 
+ * Timeout for stopping processes
+ */
+unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
+
+static int try_to_freeze_tasks(bool user_only)
+{
+	struct task_struct *g, *p;
+	unsigned long end_time;
+	unsigned int todo;
+	bool wq_busy = false;
+	struct timeval start, end;
+	u64 elapsed_msecs64;
+	unsigned int elapsed_msecs;
+	bool wakeup = false;
+	int sleep_usecs = USEC_PER_MSEC;
+#ifdef CONFIG_PM_SLEEP
+	char suspend_abort[MAX_SUSPEND_ABORT_LEN];
+#endif
+
+	do_gettimeofday(&start);
+
+	end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
+
+	if (!user_only)
+		freeze_workqueues_begin();
+
+	while (true) {
+		todo = 0;
+		read_lock(&tasklist_lock);
+		for_each_process_thread(g, p) {
+			if (p == current || !freeze_task(p))
+				continue;
+
+			if (!freezer_should_skip(p))
+				todo++;
+		}
+		read_unlock(&tasklist_lock);
+
+		if (!user_only) {
+			wq_busy = freeze_workqueues_busy();
+			todo += wq_busy;
+		}
+
+		if (!todo || time_after(jiffies, end_time))
+			break;
+
+		if (pm_wakeup_pending()) {
+#ifdef CONFIG_PM_SLEEP
+			pm_get_active_wakeup_sources(suspend_abort,
+				MAX_SUSPEND_ABORT_LEN);
+			log_suspend_abort_reason(suspend_abort);
+#endif
+			wakeup = true;
+			break;
+		}
+
+		/*
+		 * We need to retry, but first give the freezing tasks some
+		 * time to enter the refrigerator.  Start with an initial
+		 * 1 ms sleep followed by exponential backoff until 8 ms.
+		 */
+		usleep_range(sleep_usecs / 2, sleep_usecs);
+		if (sleep_usecs < 8 * USEC_PER_MSEC)
+			sleep_usecs *= 2;
+	}
+
+	do_gettimeofday(&end);
+	elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
+	do_div(elapsed_msecs64, NSEC_PER_MSEC);
+	elapsed_msecs = elapsed_msecs64;
+
+	if (wakeup) {
+		printk("\n");
+		printk(KERN_ERR "Freezing of tasks aborted after %d.%03d seconds",
+		       elapsed_msecs / 1000, elapsed_msecs % 1000);
+	} else if (todo) {
+		printk("\n");
+		printk(KERN_ERR "Freezing of tasks failed after %d.%03d seconds"
+		       " (%d tasks refusing to freeze, wq_busy=%d):\n",
+		       elapsed_msecs / 1000, elapsed_msecs % 1000,
+		       todo - wq_busy, wq_busy);
+
+			read_lock(&tasklist_lock);
+			for_each_process_thread(g, p) {
+				if (p != current && !freezer_should_skip(p)
+				    && freezing(p) && !frozen(p))
+					sched_show_task(p);
+			}
+			read_unlock(&tasklist_lock);
+	} else {
+		printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
+			elapsed_msecs % 1000);
+	}
+
+	return todo ? -EBUSY : 0;
+}
+
+static bool __check_frozen_processes(void)
+{
+	struct task_struct *g, *p;
+
+	for_each_process_thread(g, p)
+		if (p != current && !freezer_should_skip(p) && !frozen(p))
+			return false;
+
+	return true;
+}
+
+/*
+ * Returns true if all freezable tasks (except for current) are frozen already
+ */
+static bool check_frozen_processes(void)
+{
+	bool ret;
+
+	read_lock(&tasklist_lock);
+	ret = __check_frozen_processes();
+	read_unlock(&tasklist_lock);
+	return ret;
+}
+
+/**
+ * freeze_processes - Signal user space processes to enter the refrigerator.
+ * The current thread will not be frozen.  The same process that calls
+ * freeze_processes must later call thaw_processes.
+ *
+ * On success, returns 0.  On failure, -errno and system is fully thawed.
+ */
+int freeze_processes(void)
+{
+	int error;
+	int oom_kills_saved;
+
+	error = __usermodehelper_disable(UMH_FREEZING);
+	if (error)
+		return error;
+
+	/* Make sure this task doesn't get frozen */
+	current->flags |= PF_SUSPEND_TASK;
+
+	if (!pm_freezing)
+		atomic_inc(&system_freezing_cnt);
+
+	pm_wakeup_clear();
+	printk("Freezing user space processes ... ");
+	pm_freezing = true;
+	oom_kills_saved = oom_kills_count();
+	error = try_to_freeze_tasks(true);
+	if (!error) {
+		__usermodehelper_set_disable_depth(UMH_DISABLED);
+		oom_killer_disable();
+
+		/*
+		 * There might have been an OOM kill while we were
+		 * freezing tasks and the killed task might be still
+		 * on the way out so we have to double check for race.
+		 */
+		if (oom_kills_count() != oom_kills_saved &&
+		    !check_frozen_processes()) {
+			__usermodehelper_set_disable_depth(UMH_ENABLED);
+			printk("OOM in progress.");
+			error = -EBUSY;
+		} else {
+			printk("done.");
+		}
+	}
+	printk("\n");
+	BUG_ON(in_atomic());
+
+	if (error)
+		thaw_processes();
+	return error;
+}
+
+/**
+ * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
+ *
+ * On success, returns 0.  On failure, -errno and only the kernel threads are
+ * thawed, so as to give a chance to the caller to do additional cleanups
+ * (if any) before thawing the userspace tasks. So, it is the responsibility
+ * of the caller to thaw the userspace tasks, when the time is right.
+ */
+int freeze_kernel_threads(void)
+{
+	int error;
+
+	printk("Freezing remaining freezable tasks ... ");
+	pm_nosig_freezing = true;
+	error = try_to_freeze_tasks(false);
+	if (!error)
+		printk("done.");
+
+	printk("\n");
+	BUG_ON(in_atomic());
+
+	if (error)
+		thaw_kernel_threads();
+	return error;
+}
+
+void thaw_processes(void)
+{
+	struct task_struct *g, *p;
+	struct task_struct *curr = current;
+
+	trace_suspend_resume(TPS("thaw_processes"), 0, true);
+	if (pm_freezing)
+		atomic_dec(&system_freezing_cnt);
+	pm_freezing = false;
+	pm_nosig_freezing = false;
+
+	oom_killer_enable();
+
+	printk("Restarting tasks ... ");
+
+	__usermodehelper_set_disable_depth(UMH_FREEZING);
+	thaw_workqueues();
+
+	read_lock(&tasklist_lock);
+	for_each_process_thread(g, p) {
+		/* No other threads should have PF_SUSPEND_TASK set */
+		WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
+		__thaw_task(p);
+	}
+	read_unlock(&tasklist_lock);
+
+	WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
+	curr->flags &= ~PF_SUSPEND_TASK;
+
+	usermodehelper_enable();
+
+	schedule();
+	printk("done.\n");
+	trace_suspend_resume(TPS("thaw_processes"), 0, false);
+}
+
+void thaw_kernel_threads(void)
+{
+	struct task_struct *g, *p;
+
+	pm_nosig_freezing = false;
+	printk("Restarting kernel threads ... ");
+
+	thaw_workqueues();
+
+	read_lock(&tasklist_lock);
+	for_each_process_thread(g, p) {
+		if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
+			__thaw_task(p);
+	}
+	read_unlock(&tasklist_lock);
+
+	schedule();
+	printk("done.\n");
+}