[PATCH 5.4 21/34] usb: musb: Fix runtime PM imbalance on error

[Greg Kroah-Hartman]

From: Dinghao Liu <dinghao.liu@xxxxxxxxxx>

commit e4befc121df03dc8ed2ac1031c98f9538e244bae upstream.

When copy_from_user() returns an error code, there
is a runtime PM usage counter imbalance.

Fix this by moving copy_from_user() to the beginning
of this function.

Fixes: 7b6c1b4c0e1e ("usb: musb: fix runtime PM in debugfs")

Signed-off-by: Dinghao Liu <dinghao.liu@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Bin Liu <b-liu@xxxxxx>
Link: https://lore.kernel.org/r/20200525025049.3400-7-b-liu@xxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/musb/musb_debugfs.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/usb/musb/musb_debugfs.c
+++ b/drivers/usb/musb/musb_debugfs.c
@@ -168,6 +168,11 @@ static ssize_t musb_test_mode_write(stru
 	u8			test;
 	char			buf[24];
 
+	memset(buf, 0x00, sizeof(buf));
+
+	if (copy_from_user(buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
+		return -EFAULT;
+
 	pm_runtime_get_sync(musb->controller);
 	test = musb_readb(musb->mregs, MUSB_TESTMODE);
 	if (test) {
@@ -176,11 +181,6 @@ static ssize_t musb_test_mode_write(stru
 		goto ret;
 	}
 
-	memset(buf, 0x00, sizeof(buf));
-
-	if (copy_from_user(buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
-		return -EFAULT;
-
 	if (strstarts(buf, "force host full-speed"))
 		test = MUSB_TEST_FORCE_HOST | MUSB_TEST_FORCE_FS;