[PATCH v2 2/2] mtd: slram: simplify register_device() cleanup

[Ruoyu Wang]

Use local variables for the list entry, mtd_info, and private data while
initializing a new device. This keeps the initialization path easier to
read and publishes the new list entry only after mtd_device_register()
has succeeded.

Signed-off-by: Ruoyu Wang <ruoyuw560 at gmail.com>
---
 drivers/mtd/devices/slram.c | 86 ++++++++++++++++++-------------------
 1 file changed, 42 insertions(+), 44 deletions(-)

diff --git a/drivers/mtd/devices/slram.c b/drivers/mtd/devices/slram.c
index 48c2bc6b65eec..aa38ecdffc975 100644
--- a/drivers/mtd/devices/slram.c
+++ b/drivers/mtd/devices/slram.c
@@ -129,6 +129,9 @@ static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
 static int register_device(char *name, unsigned long start, unsigned long length)
 {
 	slram_mtd_list_t **curmtd;
+	slram_mtd_list_t *new_mtd;
+	struct mtd_info *mtdinfo;
+	slram_priv_t *priv;
 	int ret = -ENOMEM;
 
 	curmtd = &slram_mtdlist;
@@ -136,73 +139,68 @@ static int register_device(char *name, unsigned long start, unsigned long length
 		curmtd = &(*curmtd)->next;
 	}
 
-	*curmtd = kmalloc_obj(slram_mtd_list_t);
-	if (!(*curmtd)) {
+	new_mtd = kmalloc_obj(slram_mtd_list_t);
+	if (!new_mtd) {
 		E("slram: Cannot allocate new MTD device.\n");
 		return(-ENOMEM);
 	}
-	(*curmtd)->mtdinfo = kzalloc_obj(struct mtd_info);
-	(*curmtd)->next = NULL;
-
-	if ((*curmtd)->mtdinfo)	{
-		(*curmtd)->mtdinfo->priv =
-			kzalloc_obj(slram_priv_t);
+	new_mtd->next = NULL;
 
-		if (!(*curmtd)->mtdinfo->priv) {
-			kfree((*curmtd)->mtdinfo);
-			(*curmtd)->mtdinfo = NULL;
-		}
+	mtdinfo = kzalloc_obj(struct mtd_info);
+	if (!mtdinfo) {
+		E("slram: Cannot allocate new MTD device.\n");
+		goto err_free_list;
 	}
+	new_mtd->mtdinfo = mtdinfo;
 
-	if (!(*curmtd)->mtdinfo) {
+	priv = kzalloc_obj(slram_priv_t);
+	if (!priv) {
 		E("slram: Cannot allocate new MTD device.\n");
-		goto err_free_list;
+		goto err_free_mtdinfo;
 	}
+	mtdinfo->priv = priv;
 
-	if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
-		memremap(start, length,
-			 MEMREMAP_WB | MEMREMAP_WT | MEMREMAP_WC))) {
+	priv->start = memremap(start, length,
+			       MEMREMAP_WB | MEMREMAP_WT | MEMREMAP_WC);
+	if (!priv->start) {
 		E("slram: memremap failed\n");
 		ret = -EIO;
 		goto err_free_priv;
 	}
-	((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
-		((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
-
-
-	(*curmtd)->mtdinfo->name = name;
-	(*curmtd)->mtdinfo->size = length;
-	(*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
-	(*curmtd)->mtdinfo->_erase = slram_erase;
-	(*curmtd)->mtdinfo->_point = slram_point;
-	(*curmtd)->mtdinfo->_unpoint = slram_unpoint;
-	(*curmtd)->mtdinfo->_read = slram_read;
-	(*curmtd)->mtdinfo->_write = slram_write;
-	(*curmtd)->mtdinfo->owner = THIS_MODULE;
-	(*curmtd)->mtdinfo->type = MTD_RAM;
-	(*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
-	(*curmtd)->mtdinfo->writesize = 1;
-
-	if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0))	{
+	priv->end = priv->start + length;
+
+	mtdinfo->name = name;
+	mtdinfo->size = length;
+	mtdinfo->flags = MTD_CAP_RAM;
+	mtdinfo->_erase = slram_erase;
+	mtdinfo->_point = slram_point;
+	mtdinfo->_unpoint = slram_unpoint;
+	mtdinfo->_read = slram_read;
+	mtdinfo->_write = slram_write;
+	mtdinfo->owner = THIS_MODULE;
+	mtdinfo->type = MTD_RAM;
+	mtdinfo->erasesize = SLRAM_BLK_SZ;
+	mtdinfo->writesize = 1;
+
+	if (mtd_device_register(mtdinfo, NULL, 0)) {
 		E("slram: Failed to register new device\n");
 		ret = -EAGAIN;
 		goto err_unmap;
 	}
+	*curmtd = new_mtd;
 	T("slram: Registered device %s from %luKiB to %luKiB\n", name,
 			(start / 1024), ((start + length) / 1024));
-	T("slram: Mapped from 0x%p to 0x%p\n",
-			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
-			((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
-	return(0);
+	T("slram: Mapped from 0x%p to 0x%p\n", priv->start, priv->end);
+	return 0;
 
 err_unmap:
-	memunmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
+	memunmap(priv->start);
 err_free_priv:
-	kfree((*curmtd)->mtdinfo->priv);
+	kfree(priv);
+err_free_mtdinfo:
+	kfree(mtdinfo);
 err_free_list:
-	kfree((*curmtd)->mtdinfo);
-	kfree(*curmtd);
-	*curmtd = NULL;
+	kfree(new_mtd);
 	return ret;
 }
 
-- 
2.51.0