Input: serio_raw - return proper result when serio_raw_read fails

serio_raw_read now returns (sometimes partially) successful number of
bytes transferred to the caller, and only returns error code to the
caller on completely failed transfers.

Signed-off-by: Che-Liang Chiou <clchiou@chromium.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/input/serio/serio_raw.c b/drivers/input/serio/serio_raw.c
index 8250299fd64f..4494233d331a 100644
--- a/drivers/input/serio/serio_raw.c
+++ b/drivers/input/serio/serio_raw.c
@@ -164,7 +164,8 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer,
         struct serio_raw_client *client = file->private_data;
         struct serio_raw *serio_raw = client->serio_raw;
         char uninitialized_var(c);
-        ssize_t retval = 0;
+        ssize_t read = 0;
+        int retval;
 
         if (serio_raw->dead)
                 return -ENODEV;
@@ -180,13 +181,15 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer,
         if (serio_raw->dead)
                 return -ENODEV;
 
-        while (retval < count && serio_raw_fetch_byte(serio_raw, &c)) {
-                if (put_user(c, buffer++))
-                        return -EFAULT;
-                retval++;
+        while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
+                if (put_user(c, buffer++)) {
+                        retval = -EFAULT;
+                        break;
+                }
+                read++;
         }
 
-        return retval;
+        return read ?: retval;
 }
 
 static ssize_t serio_raw_write(struct file *file, const char __user *buffer,