2023-04-05 09:42:19

by Badhri Jagan Sridharan

Subject: [PATCH v1 2/2] usb: gadget: udc: core: Prevent redundant calls to pullup

usb_gadget_connect calls gadget->ops->pullup without
checking whether gadget->connected was previously set.
Make this symmetric to usb_gadget_disconnect by returning
early if gadget->connected is already set.

Cc: [email protected]

Signed-off-by: Badhri Jagan Sridharan <[email protected]>
Fixes: 5a1da544e572 ("usb: gadget: core: do not try to disconnect gadget if it is not connected")
---
drivers/usb/gadget/udc/core.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 890f92cb6344..7eeaf7dbb350 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -708,6 +708,9 @@ int usb_gadget_connect(struct usb_gadget *gadget)
goto out;
}

+ if (gadget->connected)
+ goto out;
+
if (gadget->deactivated) {
/*
* If gadget is deactivated we only save new state.
--
2.40.0.348.gf938b09366-goog

2023-04-05 17:22:30

by Greg Kroah-Hartman

Subject: Re: [PATCH v1 2/2] usb: gadget: udc: core: Prevent redundant calls to pullup

On Wed, Apr 05, 2023 at 09:31:33AM +0000, Badhri Jagan Sridharan wrote:
> usb_gadget_connect calls gadget->ops->pullup without
> checking whether gadget->connected was previously set.
> Make this symmetric to usb_gadget_disconnect by returning
> early if gadget->connected is already set.
>
> Cc: [email protected]
>
> Signed-off-by: Badhri Jagan Sridharan <[email protected]>
> Fixes: 5a1da544e572 ("usb: gadget: core: do not try to disconnect gadget if it is not connected")

Same changelog comment as before.

> ---
> drivers/usb/gadget/udc/core.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 890f92cb6344..7eeaf7dbb350 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -708,6 +708,9 @@ int usb_gadget_connect(struct usb_gadget *gadget)
> goto out;
> }
>
> + if (gadget->connected)
> + goto out;
> +

What prevents this connected value from changing right after you check
this?

thanks,

greg k-h

2023-04-06 06:54:50

by Badhri Jagan Sridharan

Subject: Re: [PATCH v1 2/2] usb: gadget: udc: core: Prevent redundant calls to pullup

On Wed, Apr 5, 2023 at 10:16 AM Greg KH <[email protected]> wrote:
>
> On Wed, Apr 05, 2023 at 09:31:33AM +0000, Badhri Jagan Sridharan wrote:
> > usb_gadget_connect calls gadget->ops->pullup without
> > checking whether gadget->connected was previously set.
> > Make this symmetric to usb_gadget_disconnect by returning
> > early if gadget->connected is already set.
> >
> > Cc: [email protected]
> >
> > Signed-off-by: Badhri Jagan Sridharan <[email protected]>
> > Fixes: 5a1da544e572 ("usb: gadget: core: do not try to disconnect gadget if it is not connected")
>
> Same changelog comment as before.
Thanks for the feedback Greg ! Have fixed it in v2.

>
> > ---
> > drivers/usb/gadget/udc/core.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> > index 890f92cb6344..7eeaf7dbb350 100644
> > --- a/drivers/usb/gadget/udc/core.c
> > +++ b/drivers/usb/gadget/udc/core.c
> > @@ -708,6 +708,9 @@ int usb_gadget_connect(struct usb_gadget *gadget)
> > goto out;
> > }
> >
> > + if (gadget->connected)
> > + goto out;
> > +
>
> What prevents this connected value from changing right after you check
> this?

Nothing in V1 :) However, in v2, the newly introduced mutex guards
gadget->connected
as well.

>
> thanks,
>
> greg k-h