mm/damon/dbgfs: remove unnecessary variables

In some functions, it's unnecessary to declare 'err' and 'ret' variables
at the same time.  This patch mainly to simplify the issue of such
declarations by reusing one variable.

Link: https://lkml.kernel.org/r/20211014073014.35754-1-sj@kernel.org
Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com>
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>

mm/damon/dbgfs.c

@@ -69,8 +69,7 @@ static ssize_t dbgfs_attrs_write(struct file *file,
 	struct damon_ctx *ctx = file->private_data;
 	unsigned long s, a, r, minr, maxr;
 	char *kbuf;
-	ssize_t ret = count;
-	int err;
+	ssize_t ret;
 
 	kbuf = user_input_str(buf, count, ppos);
 	if (IS_ERR(kbuf))
@@ -88,9 +87,9 @@ static ssize_t dbgfs_attrs_write(struct file *file,
 		goto unlock_out;
 	}
 
-	err = damon_set_attrs(ctx, s, a, r, minr, maxr);
-	if (err)
-		ret = err;
+	ret = damon_set_attrs(ctx, s, a, r, minr, maxr);
+	if (!ret)
+		ret = count;
 unlock_out:
 	mutex_unlock(&ctx->kdamond_lock);
 out:
@@ -220,14 +219,13 @@ static ssize_t dbgfs_schemes_write(struct file *file, const char __user *buf,
 	struct damon_ctx *ctx = file->private_data;
 	char *kbuf;
 	struct damos **schemes;
-	ssize_t nr_schemes = 0, ret = count;
-	int err;
+	ssize_t nr_schemes = 0, ret;
 
 	kbuf = user_input_str(buf, count, ppos);
 	if (IS_ERR(kbuf))
 		return PTR_ERR(kbuf);
 
-	schemes = str_to_schemes(kbuf, ret, &nr_schemes);
+	schemes = str_to_schemes(kbuf, count, &nr_schemes);
 	if (!schemes) {
 		ret = -EINVAL;
 		goto out;
@@ -239,11 +237,12 @@ static ssize_t dbgfs_schemes_write(struct file *file, const char __user *buf,
 		goto unlock_out;
 	}
 
-	err = damon_set_schemes(ctx, schemes, nr_schemes);
-	if (err)
-		ret = err;
-	else
+	ret = damon_set_schemes(ctx, schemes, nr_schemes);
+	if (!ret) {
+		ret = count;
 		nr_schemes = 0;
+	}
+
 unlock_out:
 	mutex_unlock(&ctx->kdamond_lock);
 	free_schemes_arr(schemes, nr_schemes);
@@ -343,9 +342,8 @@ static ssize_t dbgfs_target_ids_write(struct file *file,
 	char *kbuf, *nrs;
 	unsigned long *targets;
 	ssize_t nr_targets;
-	ssize_t ret = count;
+	ssize_t ret;
 	int i;
-	int err;
 
 	kbuf = user_input_str(buf, count, ppos);
 	if (IS_ERR(kbuf))
@@ -358,7 +356,7 @@ static ssize_t dbgfs_target_ids_write(struct file *file,
 		scnprintf(kbuf, count, "42    ");
 	}
 
-	targets = str_to_target_ids(nrs, ret, &nr_targets);
+	targets = str_to_target_ids(nrs, count, &nr_targets);
 	if (!targets) {
 		ret = -ENOMEM;
 		goto out;
@@ -393,11 +391,12 @@ static ssize_t dbgfs_target_ids_write(struct file *file,
 	else
 		damon_pa_set_primitives(ctx);
 
-	err = damon_set_targets(ctx, targets, nr_targets);
-	if (err) {
+	ret = damon_set_targets(ctx, targets, nr_targets);
+	if (ret) {
 		if (id_is_pid)
 			dbgfs_put_pids(targets, nr_targets);
-		ret = err;
+	} else {
+		ret = count;
 	}
 
 unlock_out:
@@ -715,8 +714,7 @@ static ssize_t dbgfs_mk_context_write(struct file *file,
 {
 	char *kbuf;
 	char *ctx_name;
-	ssize_t ret = count;
-	int err;
+	ssize_t ret;
 
 	kbuf = user_input_str(buf, count, ppos);
 	if (IS_ERR(kbuf))
@@ -734,9 +732,9 @@ static ssize_t dbgfs_mk_context_write(struct file *file,
 	}
 
 	mutex_lock(&damon_dbgfs_lock);
-	err = dbgfs_mk_context(ctx_name);
-	if (err)
-		ret = err;
+	ret = dbgfs_mk_context(ctx_name);
+	if (!ret)
+		ret = count;
 	mutex_unlock(&damon_dbgfs_lock);
 
 out:
@@ -805,8 +803,7 @@ 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;
+	ssize_t ret;
 	char *ctx_name;
 
 	kbuf = user_input_str(buf, count, ppos);
@@ -825,9 +822,9 @@ static ssize_t dbgfs_rm_context_write(struct file *file,
 	}
 
 	mutex_lock(&damon_dbgfs_lock);
-	err = dbgfs_rm_context(ctx_name);
-	if (err)
-		ret = err;
+	ret = dbgfs_rm_context(ctx_name);
+	if (!ret)
+		ret = count;
 	mutex_unlock(&damon_dbgfs_lock);
 
 out:
@@ -851,9 +848,8 @@ static ssize_t dbgfs_monitor_on_read(struct file *file,
 static ssize_t dbgfs_monitor_on_write(struct file *file,
 		const char __user *buf, size_t count, loff_t *ppos)
 {
-	ssize_t ret = count;
+	ssize_t ret;
 	char *kbuf;
-	int err;
 
 	kbuf = user_input_str(buf, count, ppos);
 	if (IS_ERR(kbuf))
@@ -866,14 +862,14 @@ static ssize_t dbgfs_monitor_on_write(struct file *file,
 	}
 
 	if (!strncmp(kbuf, "on", count))
-		err = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs);
+		ret = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs);
 	else if (!strncmp(kbuf, "off", count))
-		err = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs);
+		ret = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs);
 	else
-		err = -EINVAL;
+		ret = -EINVAL;
 
-	if (err)
-		ret = err;
+	if (!ret)
+		ret = count;
 	kfree(kbuf);
 	return ret;
 }