linux-kernel - Re: Re: [PATCH] usb: musb: Fix runtime PM imbalance on error

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Date:   Fri, 22 May 2020 09:23:01 +0800 (GMT+08:00)
From:   dinghao.liu@....edu.cn
To:     "Bin Liu" <b-liu@...com>
Cc:     kjlu@....edu, "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Re: [PATCH] usb: musb: Fix runtime PM imbalance on error

Sure.

Regards,
Dinghao

> Hi,
> 
> On Thu, May 21, 2020 at 03:35:47PM +0800, Dinghao Liu wrote:
> > When copy_from_user() returns an error code, a pairing
> > runtime PM usage counter decrement is needed to keep
> > the counter balanced.
> > 
> > Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
> > ---
> >  drivers/usb/musb/musb_debugfs.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/usb/musb/musb_debugfs.c b/drivers/usb/musb/musb_debugfs.c
> > index 7b6281ab62ed..837c38a5e4ef 100644
> > --- a/drivers/usb/musb/musb_debugfs.c
> > +++ b/drivers/usb/musb/musb_debugfs.c
> > @@ -178,8 +178,11 @@ static ssize_t musb_test_mode_write(struct file *file,
> >  
> >  	memset(buf, 0x00, sizeof(buf));
> >  
> > -	if (copy_from_user(buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
> > +	if (copy_from_user(buf, ubuf, min_t(size_t, sizeof(buf) - 1, count))) {
> > +		pm_runtime_mark_last_busy(musb->controller);
> > +		pm_runtime_put_autosuspend(musb->controller);
> >  		return -EFAULT;
> > +	}
> 
> Thanks for catching the bug. Can you please instead move these lines to
> the beginning of this function so that pm_runtime_get_sync() is not
> called if copy_from_user() failed?
> 
> -Bin.