2021-08-02 22:24:10

by Salah Triki

Subject: [PATCH] usb: misc: chaoskey: get lock before calling usb_[disable|enable]_autosuspend()

Based on the documentation of usb_[disable|enable]_autosuspend(), the
caller must hold udev's device lock.

Signed-off-by: Salah Triki <[email protected]>
---
drivers/usb/misc/chaoskey.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index 87067c3d6109..8af00be7b9e8 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -206,7 +206,9 @@ static int chaoskey_probe(struct usb_interface *interface,
if (!dev->hwrng_registered)
usb_err(interface, "Unable to register with hwrng");

+ usb_lock_device(udev);
usb_enable_autosuspend(udev);
+ usb_unlock_device(udev);

usb_dbg(interface, "chaoskey probe success, size %d", dev->size);
return 0;
--
2.25.1

2021-08-03 00:59:36

by Alan Stern

Subject: Re: [PATCH] usb: misc: chaoskey: get lock before calling usb_[disable|enable]_autosuspend()

On Mon, Aug 02, 2021 at 11:22:05PM +0100, Salah Triki wrote:
> Based on the documentation of usb_[disable|enable]_autosuspend(), the
> caller must hold udev's device lock.
>
> Signed-off-by: Salah Triki <[email protected]>
> ---
> drivers/usb/misc/chaoskey.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
> index 87067c3d6109..8af00be7b9e8 100644
> --- a/drivers/usb/misc/chaoskey.c
> +++ b/drivers/usb/misc/chaoskey.c
> @@ -206,7 +206,9 @@ static int chaoskey_probe(struct usb_interface *interface,
> if (!dev->hwrng_registered)
> usb_err(interface, "Unable to register with hwrng");
>
> + usb_lock_device(udev);
> usb_enable_autosuspend(udev);
> + usb_unlock_device(udev);

Not needed (indeed, actively harmful). When this code runs it already
holds the device lock, because it is part of a probe routine.

Alan Stern