1 files changed, 193 insertions, 2 deletions

diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index e850be4077f5..31ad550ecba2 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -18,6 +18,7 @@
 static struct damon_ctx **dbgfs_ctxs;
 static int dbgfs_nr_ctxs;
 static struct dentry **dbgfs_dirs;
+static DEFINE_MUTEX(damon_dbgfs_lock);
 
 /*
  * Returns non-empty string on success, negative error code otherwise.
@@ -328,6 +329,186 @@ static struct damon_ctx *dbgfs_new_ctx(void)
 	return ctx;
 }
 
+static void dbgfs_destroy_ctx(struct damon_ctx *ctx)
+{
+	damon_destroy_ctx(ctx);
+}
+
+/*
+ * Make a context of @name and create a debugfs directory for it.
+ *
+ * This function should be called while holding damon_dbgfs_lock.
+ *
+ * Returns 0 on success, negative error code otherwise.
+ */
+static int dbgfs_mk_context(char *name)
+{
+	struct dentry *root, **new_dirs, *new_dir;
+	struct damon_ctx **new_ctxs, *new_ctx;
+
+	if (damon_nr_running_ctxs())
+		return -EBUSY;
+
+	new_ctxs = krealloc(dbgfs_ctxs, sizeof(*dbgfs_ctxs) *
+			(dbgfs_nr_ctxs + 1), GFP_KERNEL);
+	if (!new_ctxs)
+		return -ENOMEM;
+	dbgfs_ctxs = new_ctxs;
+
+	new_dirs = krealloc(dbgfs_dirs, sizeof(*dbgfs_dirs) *
+			(dbgfs_nr_ctxs + 1), GFP_KERNEL);
+	if (!new_dirs)
+		return -ENOMEM;
+	dbgfs_dirs = new_dirs;
+
+	root = dbgfs_dirs[0];
+	if (!root)
+		return -ENOENT;
+
+	new_dir = debugfs_create_dir(name, root);
+	dbgfs_dirs[dbgfs_nr_ctxs] = new_dir;
+
+	new_ctx = dbgfs_new_ctx();
+	if (!new_ctx) {
+		debugfs_remove(new_dir);
+		dbgfs_dirs[dbgfs_nr_ctxs] = NULL;
+		return -ENOMEM;
+	}
+
+	dbgfs_ctxs[dbgfs_nr_ctxs] = new_ctx;
+	dbgfs_fill_ctx_dir(dbgfs_dirs[dbgfs_nr_ctxs],
+			dbgfs_ctxs[dbgfs_nr_ctxs]);
+	dbgfs_nr_ctxs++;
+
+	return 0;
+}
+
+static ssize_t dbgfs_mk_context_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	char *kbuf;
+	char *ctx_name;
+	ssize_t ret = count;
+	int err;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+	ctx_name = kmalloc(count + 1, GFP_KERNEL);
+	if (!ctx_name) {
+		kfree(kbuf);
+		return -ENOMEM;
+	}
+
+	/* Trim white space */
+	if (sscanf(kbuf, "%s", ctx_name) != 1) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mutex_lock(&damon_dbgfs_lock);
+	err = dbgfs_mk_context(ctx_name);
+	if (err)
+		ret = err;
+	mutex_unlock(&damon_dbgfs_lock);
+
+out:
+	kfree(kbuf);
+	kfree(ctx_name);
+	return ret;
+}
+
+/*
+ * Remove a context of @name and its debugfs directory.
+ *
+ * This function should be called while holding damon_dbgfs_lock.
+ *
+ * Return 0 on success, negative error code otherwise.
+ */
+static int dbgfs_rm_context(char *name)
+{
+	struct dentry *root, *dir, **new_dirs;
+	struct damon_ctx **new_ctxs;
+	int i, j;
+
+	if (damon_nr_running_ctxs())
+		return -EBUSY;
+
+	root = dbgfs_dirs[0];
+	if (!root)
+		return -ENOENT;
+
+	dir = debugfs_lookup(name, root);
+	if (!dir)
+		return -ENOENT;
+
+	new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs),
+			GFP_KERNEL);
+	if (!new_dirs)
+		return -ENOMEM;
+
+	new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs),
+			GFP_KERNEL);
+	if (!new_ctxs) {
+		kfree(new_dirs);
+		return -ENOMEM;
+	}
+
+	for (i = 0, j = 0; i < dbgfs_nr_ctxs; i++) {
+		if (dbgfs_dirs[i] == dir) {
+			debugfs_remove(dbgfs_dirs[i]);
+			dbgfs_destroy_ctx(dbgfs_ctxs[i]);
+			continue;
+		}
+		new_dirs[j] = dbgfs_dirs[i];
+		new_ctxs[j++] = dbgfs_ctxs[i];
+	}
+
+	kfree(dbgfs_dirs);
+	kfree(dbgfs_ctxs);
+
+	dbgfs_dirs = new_dirs;
+	dbgfs_ctxs = new_ctxs;
+	dbgfs_nr_ctxs--;
+
+	return 0;
+}
+
+static ssize_t dbgfs_rm_context_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	char *kbuf;
+	ssize_t ret = count;
+	int err;
+	char *ctx_name;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+	ctx_name = kmalloc(count + 1, GFP_KERNEL);
+	if (!ctx_name) {
+		kfree(kbuf);
+		return -ENOMEM;
+	}
+
+	/* Trim white space */
+	if (sscanf(kbuf, "%s", ctx_name) != 1) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mutex_lock(&damon_dbgfs_lock);
+	err = dbgfs_rm_context(ctx_name);
+	if (err)
+		ret = err;
+	mutex_unlock(&damon_dbgfs_lock);
+
+out:
+	kfree(kbuf);
+	kfree(ctx_name);
+	return ret;
+}
+
 static ssize_t dbgfs_monitor_on_read(struct file *file,
 		char __user *buf, size_t count, loff_t *ppos)
 {
@@ -370,6 +551,14 @@ static ssize_t dbgfs_monitor_on_write(struct file *file,
 	return ret;
 }
 
+static const struct file_operations mk_contexts_fops = {
+	.write = dbgfs_mk_context_write,
+};
+
+static const struct file_operations rm_contexts_fops = {
+	.write = dbgfs_rm_context_write,
+};
+
 static const struct file_operations monitor_on_fops = {
 	.read = dbgfs_monitor_on_read,
 	.write = dbgfs_monitor_on_write,
@@ -378,8 +567,10 @@ static const struct file_operations monitor_on_fops = {
 static int __init __damon_dbgfs_init(void)
 {
 	struct dentry *dbgfs_root;
-	const char * const file_names[] = {"monitor_on"};
-	const struct file_operations *fops[] = {&monitor_on_fops};
+	const char * const file_names[] = {"mk_contexts", "rm_contexts",
+		"monitor_on"};
+	const struct file_operations *fops[] = {&mk_contexts_fops,
+		&rm_contexts_fops, &monitor_on_fops};
 	int i;
 
 	dbgfs_root = debugfs_create_dir("damon", NULL);