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From:   Dinghao Liu <dinghao.liu@zju.edu.cn>
To:     dinghao.liu@zju.edu.cn, kjlu@umn.edu
Cc:     Bin Liu <b-liu@ti.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] [v3] usb: musb: Fix runtime PM imbalance on error
Date:   Fri, 22 May 2020 13:42:35 +0800
Message-Id: <20200522054235.7944-1-dinghao.liu@zju.edu.cn>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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.

Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
---

Changelog:

v2: - Move copy_from_user() to the beginning rather
      than adding pm_runtime_put_autosuspend().

v3: - Add missing changelog information.
---
 drivers/usb/musb/musb_debugfs.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/musb/musb_debugfs.c b/drivers/usb/musb/musb_debugfs.c
index 7b6281ab62ed..30a89aa8a3e7 100644
--- 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(struct file *file,
 	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(struct file *file,
 		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;
 
-- 
2.17.1