mm/damon/core: move damon_set_targets() into dbgfs

damon_set_targets() function is defined in the core for general use cases,
but called from only dbgfs.  Also, because the function is for general use
cases, dbgfs does additional handling of pid type target id case.  To make
the situation simpler, this commit moves the function into dbgfs and makes
it to do the pid type case handling on its own.

Link: https://lkml.kernel.org/r/20211230100723.2238-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 41 insertions, 12 deletions

diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 3f65af04e4e6..58867b966635 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -358,11 +358,48 @@ static void dbgfs_put_pids(unsigned long *ids, int nr_ids)
 		put_pid((struct pid *)ids[i]);
 }
 
+/*
+ * dbgfs_set_targets() - Set monitoring targets.
+ * @ctx:	monitoring context
+ * @ids:	array of target ids
+ * @nr_ids:	number of entries in @ids
+ *
+ * This function should not be called while the kdamond is running.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int dbgfs_set_targets(struct damon_ctx *ctx,
+		      unsigned long *ids, ssize_t nr_ids)
+{
+	ssize_t i;
+	struct damon_target *t, *next;
+
+	damon_for_each_target_safe(t, next, ctx) {
+		if (targetid_is_pid(ctx))
+			put_pid((struct pid *)t->id);
+		damon_destroy_target(t);
+	}
+
+	for (i = 0; i < nr_ids; i++) {
+		t = damon_new_target(ids[i]);
+		if (!t) {
+			/* The caller should do cleanup of the ids itself */
+			damon_for_each_target_safe(t, next, ctx)
+				damon_destroy_target(t);
+			if (targetid_is_pid(ctx))
+				dbgfs_put_pids(ids, nr_ids);
+			return -ENOMEM;
+		}
+		damon_add_target(ctx, t);
+	}
+
+	return 0;
+}
+
 static ssize_t dbgfs_target_ids_write(struct file *file,
 		const char __user *buf, size_t count, loff_t *ppos)
 {
 	struct damon_ctx *ctx = file->private_data;
-	struct damon_target *t, *next_t;
 	bool id_is_pid = true;
 	char *kbuf;
 	unsigned long *targets;
@@ -407,11 +444,7 @@ static ssize_t dbgfs_target_ids_write(struct file *file,
 	}
 
 	/* remove previously set targets */
-	damon_for_each_target_safe(t, next_t, ctx) {
-		if (targetid_is_pid(ctx))
-			put_pid((struct pid *)t->id);
-		damon_destroy_target(t);
-	}
+	dbgfs_set_targets(ctx, NULL, 0);
 
 	/* Configure the context for the address space type */
 	if (id_is_pid)
@@ -419,13 +452,9 @@ static ssize_t dbgfs_target_ids_write(struct file *file,
 	else
 		damon_pa_set_primitives(ctx);
 
-	ret = damon_set_targets(ctx, targets, nr_targets);
-	if (ret) {
-		if (id_is_pid)
-			dbgfs_put_pids(targets, nr_targets);
-	} else {
+	ret = dbgfs_set_targets(ctx, targets, nr_targets);
+	if (!ret)
 		ret = count;
-	}
 
 unlock_out:
 	mutex_unlock(&ctx->kdamond_lock);