[PATCH] Remove unnecessary kmalloc/kfree calls in mtdchar

[Thiago Galesi]

This patch removes the use of repeated calls to kmalloc / kfree when
writing / reading from a MTD char device. Not the ideal solution
mentioned in the driver, but nonetheless better.

Signed-off by Thiago Galesi <thiagogalesi@xxxxxxxxx>

---

(Please CC me as I'm not subscribed to linux-mtd)

Index: linux-2.6.16.2/drivers/mtd/mtdchar.c
===================================================================
--- linux-2.6.16.2.orig/drivers/mtd/mtdchar.c
+++ linux-2.6.16.2/drivers/mtd/mtdchar.c
@@ -170,15 +170,18 @@ static ssize_t mtd_read(struct file *fil

 	/* FIXME: Use kiovec in 2.5 to lock down the user's buffers
 	   and pass them directly to the MTD functions */
-	while (count) {
-		if (count > MAX_KMALLOC_SIZE)
-			len = MAX_KMALLOC_SIZE;
-		else
-			len = count;

-		kbuf=kmalloc(len,GFP_KERNEL);
-		if (!kbuf)
-			return -ENOMEM;
+	if (count > MAX_KMALLOC_SIZE)
+		len = MAX_KMALLOC_SIZE;
+	else
+		len = count;
+
+	kbuf=kmalloc(len,GFP_KERNEL);
+
+	if (!kbuf)
+		return -ENOMEM;
+
+	while (count) {

 		switch (MTD_MODE(file)) {
 		case MTD_MODE_OTP_FACT:
@@ -215,9 +218,9 @@ static ssize_t mtd_read(struct file *fil
 			return ret;
 		}

-		kfree(kbuf);
 	}

+	kfree(kbuf);
 	return total_retlen;
 } /* mtd_read */

@@ -241,17 +244,18 @@ static ssize_t mtd_write(struct file *fi
 	if (!count)
 		return 0;

-	while (count) {
-		if (count > MAX_KMALLOC_SIZE)
-			len = MAX_KMALLOC_SIZE;
-		else
-			len = count;
+	if (count > MAX_KMALLOC_SIZE)
+		len = MAX_KMALLOC_SIZE;
+	else
+		len = count;
+
+	kbuf=kmalloc(len,GFP_KERNEL);
+	if (!kbuf) {
+		printk("kmalloc is null\n");
+		return -ENOMEM;
+	}

-		kbuf=kmalloc(len,GFP_KERNEL);
-		if (!kbuf) {
-			printk("kmalloc is null\n");
-			return -ENOMEM;
-		}
+	while (count) {

 		if (copy_from_user(kbuf, buf, len)) {
 			kfree(kbuf);
@@ -282,10 +286,9 @@ static ssize_t mtd_write(struct file *fi
 			kfree(kbuf);
 			return ret;
 		}
-
-		kfree(kbuf);
 	}

+	kfree(kbuf);
 	return total_retlen;
 } /* mtd_write */
-
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