From 73f1dd691f22d58c9bfb970cb8b5a3b25fb4f3c3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= <arve@android.com>
Date: Tue, 25 Sep 2012 17:37:14 -0700
Subject: [PATCH] ANDROID: staging: lowmemorykiller: Add config option to
 support oom_adj values
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The conversion to use oom_score_adj instead of the deprecated oom_adj
values breaks existing user-space code. Add a config option to convert
oom_adj values written to oom_score_adj values if they appear to be
valid oom_adj values.

Change-Id: I68308125059b802ee2991feefb07e9703bc48549
Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 drivers/staging/android/Kconfig           |  9 +++
 drivers/staging/android/lowmemorykiller.c | 85 +++++++++++++++++++++++
 2 files changed, 94 insertions(+)

diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig
index 6c00d6f765c6..e41327aad492 100644
--- a/drivers/staging/android/Kconfig
+++ b/drivers/staging/android/Kconfig
@@ -24,6 +24,15 @@ config ANDROID_LOW_MEMORY_KILLER
 	  scripts (/init.rc), and it defines priority values with minimum free memory size
 	  for each priority.
 
+config ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
+	bool "Android Low Memory Killer: detect oom_adj values"
+	depends on ANDROID_LOW_MEMORY_KILLER
+	default y
+	---help---
+	  Detect oom_adj values written to
+	  /sys/module/lowmemorykiller/parameters/adj and convert them
+	  to oom_score_adj values.
+
 source "drivers/staging/android/ion/Kconfig"
 
 endif # if ANDROID
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index ec3b66561412..9f577c0e1617 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -200,12 +200,97 @@ static int __init lowmem_init(void)
 }
 device_initcall(lowmem_init);
 
+#ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
+static short lowmem_oom_adj_to_oom_score_adj(short oom_adj)
+{
+	if (oom_adj == OOM_ADJUST_MAX)
+		return OOM_SCORE_ADJ_MAX;
+	else
+		return (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
+}
+
+static void lowmem_autodetect_oom_adj_values(void)
+{
+	int i;
+	short oom_adj;
+	short oom_score_adj;
+	int array_size = ARRAY_SIZE(lowmem_adj);
+
+	if (lowmem_adj_size < array_size)
+		array_size = lowmem_adj_size;
+
+	if (array_size <= 0)
+		return;
+
+	oom_adj = lowmem_adj[array_size - 1];
+	if (oom_adj > OOM_ADJUST_MAX)
+		return;
+
+	oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
+	if (oom_score_adj <= OOM_ADJUST_MAX)
+		return;
+
+	lowmem_print(1, "lowmem_shrink: convert oom_adj to oom_score_adj:\n");
+	for (i = 0; i < array_size; i++) {
+		oom_adj = lowmem_adj[i];
+		oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
+		lowmem_adj[i] = oom_score_adj;
+		lowmem_print(1, "oom_adj %d => oom_score_adj %d\n",
+			     oom_adj, oom_score_adj);
+	}
+}
+
+static int lowmem_adj_array_set(const char *val, const struct kernel_param *kp)
+{
+	int ret;
+
+	ret = param_array_ops.set(val, kp);
+
+	/* HACK: Autodetect oom_adj values in lowmem_adj array */
+	lowmem_autodetect_oom_adj_values();
+
+	return ret;
+}
+
+static int lowmem_adj_array_get(char *buffer, const struct kernel_param *kp)
+{
+	return param_array_ops.get(buffer, kp);
+}
+
+static void lowmem_adj_array_free(void *arg)
+{
+	param_array_ops.free(arg);
+}
+
+static struct kernel_param_ops lowmem_adj_array_ops = {
+	.set = lowmem_adj_array_set,
+	.get = lowmem_adj_array_get,
+	.free = lowmem_adj_array_free,
+};
+
+static const struct kparam_array __param_arr_adj = {
+	.max = ARRAY_SIZE(lowmem_adj),
+	.num = &lowmem_adj_size,
+	.ops = &param_ops_short,
+	.elemsize = sizeof(lowmem_adj[0]),
+	.elem = lowmem_adj,
+};
+#endif
+
 /*
  * not really modular, but the easiest way to keep compat with existing
  * bootargs behaviour is to continue using module_param here.
  */
 module_param_named(cost, lowmem_shrinker.seeks, int, 0644);
+#ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
+__module_param_call(MODULE_PARAM_PREFIX, adj,
+		    &lowmem_adj_array_ops,
+		    .arr = &__param_arr_adj,
+		    0644, -1);
+__MODULE_PARM_TYPE(adj, "array of short");
+#else
 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size, 0644);
+#endif
 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 			 0644);
 module_param_named(debug_level, lowmem_debug_level, uint, 0644);