Revert "Staging: android: delete android drivers"

This reverts commit b0a0ccfad85b3657fe999805df65f5cfe634ab8a.

Turns out I was wrong, we want these in the tree.

Note, I've disabled the drivers from the build at the moment, so other
patches can be applied to fix some build issues due to internal api
changes since the code was removed from the tree.

Cc: Arve Hjønnevåg <arve@android.com>
Cc: Brian Swetland <swetland@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 173 insertions, 0 deletions

diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
new file mode 100644
index 00000000000..935d281a201
--- /dev/null
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -0,0 +1,173 @@
+/* drivers/misc/lowmemorykiller.c
+ *
+ * The lowmemorykiller driver lets user-space specify a set of memory thresholds
+ * where processes with a range of oom_adj values will get killed. Specify the
+ * minimum oom_adj values in /sys/module/lowmemorykiller/parameters/adj and the
+ * number of free pages in /sys/module/lowmemorykiller/parameters/minfree. Both
+ * files take a comma separated list of numbers in ascending order.
+ *
+ * For example, write "0,8" to /sys/module/lowmemorykiller/parameters/adj and
+ * "1024,4096" to /sys/module/lowmemorykiller/parameters/minfree to kill processes
+ * with a oom_adj value of 8 or higher when the free memory drops below 4096 pages
+ * and kill processes with a oom_adj value of 0 or higher when the free memory
+ * drops below 1024 pages.
+ *
+ * The driver considers memory used for caches to be free, but if a large
+ * percentage of the cached memory is locked this can be very inaccurate
+ * and processes may not get killed until the normal oom killer is triggered.
+ *
+ * Copyright (C) 2007-2008 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/oom.h>
+#include <linux/sched.h>
+
+static uint32_t lowmem_debug_level = 2;
+static int lowmem_adj[6] = {
+	0,
+	1,
+	6,
+	12,
+};
+static int lowmem_adj_size = 4;
+static size_t lowmem_minfree[6] = {
+	3 * 512,	/* 6MB */
+	2 * 1024,	/* 8MB */
+	4 * 1024,	/* 16MB */
+	16 * 1024,	/* 64MB */
+};
+static int lowmem_minfree_size = 4;
+
+#define lowmem_print(level, x...)			\
+	do {						\
+		if (lowmem_debug_level >= (level))	\
+			printk(x);			\
+	} while (0)
+
+static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
+{
+	struct task_struct *p;
+	struct task_struct *selected = NULL;
+	int rem = 0;
+	int tasksize;
+	int i;
+	int min_adj = OOM_ADJUST_MAX + 1;
+	int selected_tasksize = 0;
+	int selected_oom_adj;
+	int array_size = ARRAY_SIZE(lowmem_adj);
+	int other_free = global_page_state(NR_FREE_PAGES);
+	int other_file = global_page_state(NR_FILE_PAGES);
+
+	if (lowmem_adj_size < array_size)
+		array_size = lowmem_adj_size;
+	if (lowmem_minfree_size < array_size)
+		array_size = lowmem_minfree_size;
+	for (i = 0; i < array_size; i++) {
+		if (other_free < lowmem_minfree[i] &&
+		    other_file < lowmem_minfree[i]) {
+			min_adj = lowmem_adj[i];
+			break;
+		}
+	}
+	if (nr_to_scan > 0)
+		lowmem_print(3, "lowmem_shrink %d, %x, ofree %d %d, ma %d\n",
+			     nr_to_scan, gfp_mask, other_free, other_file,
+			     min_adj);
+	rem = global_page_state(NR_ACTIVE_ANON) +
+		global_page_state(NR_ACTIVE_FILE) +
+		global_page_state(NR_INACTIVE_ANON) +
+		global_page_state(NR_INACTIVE_FILE);
+	if (nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
+		lowmem_print(5, "lowmem_shrink %d, %x, return %d\n",
+			     nr_to_scan, gfp_mask, rem);
+		return rem;
+	}
+	selected_oom_adj = min_adj;
+
+	read_lock(&tasklist_lock);
+	for_each_process(p) {
+		struct mm_struct *mm;
+		int oom_adj;
+
+		task_lock(p);
+		mm = p->mm;
+		if (!mm) {
+			task_unlock(p);
+			continue;
+		}
+		oom_adj = mm->oom_adj;
+		if (oom_adj < min_adj) {
+			task_unlock(p);
+			continue;
+		}
+		tasksize = get_mm_rss(mm);
+		task_unlock(p);
+		if (tasksize <= 0)
+			continue;
+		if (selected) {
+			if (oom_adj < selected_oom_adj)
+				continue;
+			if (oom_adj == selected_oom_adj &&
+			    tasksize <= selected_tasksize)
+				continue;
+		}
+		selected = p;
+		selected_tasksize = tasksize;
+		selected_oom_adj = oom_adj;
+		lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
+			     p->pid, p->comm, oom_adj, tasksize);
+	}
+	if (selected) {
+		lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
+			     selected->pid, selected->comm,
+			     selected_oom_adj, selected_tasksize);
+		force_sig(SIGKILL, selected);
+		rem -= selected_tasksize;
+	}
+	lowmem_print(4, "lowmem_shrink %d, %x, return %d\n",
+		     nr_to_scan, gfp_mask, rem);
+	read_unlock(&tasklist_lock);
+	return rem;
+}
+
+static struct shrinker lowmem_shrinker = {
+	.shrink = lowmem_shrink,
+	.seeks = DEFAULT_SEEKS * 16
+};
+
+static int __init lowmem_init(void)
+{
+	register_shrinker(&lowmem_shrinker);
+	return 0;
+}
+
+static void __exit lowmem_exit(void)
+{
+	unregister_shrinker(&lowmem_shrinker);
+}
+
+module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
+module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
+			 S_IRUGO | S_IWUSR);
+module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
+			 S_IRUGO | S_IWUSR);
+module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
+
+module_init(lowmem_init);
+module_exit(lowmem_exit);
+
+MODULE_LICENSE("GPL");
+