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    SubjectRe: [PATCH] usb: musb: Fix runtime PM imbalance on error
    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@zju.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.

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