[PATCH RFC 07/22] powerpc/pseries: let procfs copy in writes

@@ -498,7 +498,7 @@ static void dtl_worker_disable(unsigned long *time_limit)
 	up_write(&dtl_access_lock);
 }
 
-static ssize_t vcpudispatch_stats_write(struct file *file, const char __user *p,
+static ssize_t vcpudispatch_stats_write(struct file *file, char *p,
 		size_t count, loff_t *ppos)
 {
 	unsigned long time_limit = jiffies + HZ;

@@ -509,8 +509,7 @@ static ssize_t vcpudispatch_stats_write(struct file *file, const char __user *p,
 	if (count > 15)
 		return -EINVAL;
 
-	if (copy_from_user(buf, p, count))
-		return -EFAULT;
+	memcpy(buf, p, count);
 
 	buf[count] = 0;
 	rc = kstrtoint(buf, 0, &cmd);

@@ -586,11 +585,11 @@ static int vcpudispatch_stats_display(struct seq_file *p, void *v)
 
 static const struct proc_ops vcpudispatch_stats_proc_ops = {
 	.proc_show	= vcpudispatch_stats_display,
-	.proc_write	= vcpudispatch_stats_write,
+	.proc_write_buf	= vcpudispatch_stats_write,
 };
 
 static ssize_t vcpudispatch_stats_freq_write(struct file *file,
-		const char __user *p, size_t count, loff_t *ppos)
+		char *p, size_t count, loff_t *ppos)
 {
 	int rc, freq;
 	char buf[16];

@@ -598,8 +597,7 @@ static ssize_t vcpudispatch_stats_freq_write(struct file *file,
 	if (count > 15)
 		return -EINVAL;
 
-	if (copy_from_user(buf, p, count))
-		return -EFAULT;
+	memcpy(buf, p, count);
 
 	buf[count] = 0;
 	rc = kstrtoint(buf, 0, &freq);

@@ -622,7 +620,7 @@ static int vcpudispatch_stats_freq_display(struct seq_file *p, void *v)
 
 static const struct proc_ops vcpudispatch_stats_freq_proc_ops = {
 	.proc_show	= vcpudispatch_stats_freq_display,
-	.proc_write	= vcpudispatch_stats_freq_write,
+	.proc_write_buf	= vcpudispatch_stats_freq_write,
 };
 
 static int __init vcpudispatch_stats_procfs_init(void)

@@ -687,7 +687,7 @@ static ssize_t update_mpp(u64 *entitlement, u8 *weight)
  * This function should be invoked only on systems with
  * FW_FEATURE_SPLPAR.
  */
-static ssize_t lparcfg_write(struct file *file, const char __user * buf,
+static ssize_t lparcfg_write(struct file *file, char *buf,
 			     size_t count, loff_t * off)
 {
 	char kbuf[64];

@@ -702,8 +702,7 @@ static ssize_t lparcfg_write(struct file *file, const char __user * buf,
 	if (count == 0 || count > sizeof(kbuf))
 		return -EINVAL;
 
-	if (copy_from_user(kbuf, buf, count))
-		return -EFAULT;
+	memcpy(kbuf, buf, count);
 
 	kbuf[count - 1] = '\0';
 	tmp = strchr(kbuf, '=');

@@ -799,7 +798,7 @@ static int lparcfg_data(struct seq_file *m, void *v)
 }
 
 static const struct proc_ops lparcfg_proc_ops = {
-	.proc_write	= lparcfg_write,
+	.proc_write_buf	= lparcfg_write,
 	.proc_show	= lparcfg_data,
 };
 

@@ -349,7 +349,7 @@ static int do_update_property(char *buf, size_t bufsize)
  * ofdt_write - perform operations on the Open Firmware device tree
  *
  * @file: not used
- * @buf: command and arguments
+ * @kbuf: command and arguments
  * @count: size of the command buffer
  * @off: not used
  *

@@ -357,26 +357,19 @@ static int do_update_property(char *buf, size_t bufsize)
  * whole nodes along with their properties.  Operations on individual
  * properties are not implemented (yet).
  */
-static ssize_t ofdt_write(struct file *file, const char __user *buf, size_t count,
+static ssize_t ofdt_write(struct file *file, char *kbuf, size_t count,
 			  loff_t *off)
 {
 	int rv;
-	char *kbuf;
 	char *tmp;
 
 	rv = security_locked_down(LOCKDOWN_DEVICE_TREE);
 	if (rv)
 		return rv;
 
-	kbuf = memdup_user_nul(buf, count);
-	if (IS_ERR(kbuf))
-		return PTR_ERR(kbuf);
-
 	tmp = strchr(kbuf, ' ');
-	if (!tmp) {
-		rv = -EINVAL;
-		goto out;
-	}
+	if (!tmp)
+		return -EINVAL;
 	*tmp = '\0';
 	tmp++;
 

@@ -392,13 +385,14 @@ static ssize_t ofdt_write(struct file *file, const char __user *buf, size_t coun
 		rv = do_update_property(tmp, count - (tmp - kbuf));
 	else
 		rv = -EINVAL;
-out:
-	kfree(kbuf);
+
 	return rv ? rv : count;
 }
 
 static const struct proc_ops ofdt_proc_ops = {
-	.proc_write	= ofdt_write,
+	.proc_write_buf	= ofdt_write,
+	/* what memdup_user_nul() could copy in */
+	.proc_write_size = KMALLOC_MAX_SIZE - 1,
 	.proc_lseek	= noop_llseek,
 };