[PATCH] [v2] usb: musb: Fix runtime PM imbalance on error

[PATCH] [v2] usb: musb: Fix runtime PM imbalance on error

[Dinghao Liu]

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>
---
 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

Re: [PATCH] [v2] usb: musb: Fix runtime PM imbalance on error

[Greg Kroah-Hartman]

On Fri, May 22, 2020 at 10:59:02AM +0800, Dinghao Liu wrote:
> 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>
> ---
>  drivers/usb/musb/musb_debugfs.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)

What changed from v1?  Always show that below the --- line as the
documentation says to.

thanks,

greg k-h

Re: Re: [PATCH] [v2] usb: musb: Fix runtime PM imbalance on error

[dinghao.liu]

Sorry, it's my carelessness. In v1 I added pm_runtime_put_autosuspend()
after copy_from_user() to fix this problem. Since copy_from_user() is
moved to the beginning now, we need not to add PM decrement. 

Regards,
Dinghao

> On Fri, May 22, 2020 at 10:59:02AM +0800, Dinghao Liu wrote:
> > 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>
> > ---
> >  drivers/usb/musb/musb_debugfs.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> What changed from v1?  Always show that below the --- line as the
> documentation says to.
> 
> thanks,
> 
> greg k-h

Re: Re: [PATCH] [v2] usb: musb: Fix runtime PM imbalance on error

[Greg Kroah-Hartman]

On Fri, May 22, 2020 at 01:22:24PM +0800, dinghao.liu@zju.edu.cn wrote:
> Sorry, it's my carelessness. In v1 I added pm_runtime_put_autosuspend()
> after copy_from_user() to fix this problem. Since copy_from_user() is
> moved to the beginning now, we need not to add PM decrement. 

THat's fine, please put that information in a v3 and resend it.

thanks,

greg k-h