linux-kernel - RE: [PATCH 1/2] usb: dwc2: add ep enabled flag to avoid double enable/disable

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Message-ID: <0C18FE92A7765D4EB9EE5D38D86A563A01DF60BF@SHSMSX103.ccr.corp.intel.com>
Date:	Mon, 14 Dec 2015 03:23:29 +0000
From:	"Du, Changbin" <changbin.du@...el.com>
To:	Felipe Balbi <balbi@...com>,
	"johnyoun@...opsys.com" <johnyoun@...opsys.com>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/2] usb: dwc2: add ep enabled flag to avoid double
 enable/disable

Hi, Balbi,
Please ignore this patch set. Because we have a fix in gadget API layer.
[PATCH] usb: gadget: forbid queuing request to a disabled ep

> > Enabling an already enabled ep is illegal, because the ep may has trbs
> > running. Reprogram the ep may break running transfer. So udc driver
> > must avoid this happening by return an error -EBUSY. Gadget function
> > driver also should avoid such things, but that is out of udc driver.
> >
> > Similarly, disable a disabled ep makes no sense, but no need return
> > an error here.
> >
> > Signed-off-by: Du, Changbin <changbin.du@...el.com>
> > ---
> >  drivers/usb/dwc2/core.h   |  1 +
> >  drivers/usb/dwc2/gadget.c | 20 +++++++++++++++++++-
> >  2 files changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> > index a66d3cb..cf7eccd 100644
> > --- a/drivers/usb/dwc2/core.h
> > +++ b/drivers/usb/dwc2/core.h
> > @@ -162,6 +162,7 @@ struct dwc2_hsotg_ep {
> >  	unsigned char           mc;
> >  	unsigned char           interval;
> >
> > +	unsigned int		enabled:1;
> >  	unsigned int            halted:1;
> >  	unsigned int            periodic:1;
> >  	unsigned int            isochronous:1;
> > diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> > index 0abf73c..586bbcd 100644
> > --- a/drivers/usb/dwc2/gadget.c
> > +++ b/drivers/usb/dwc2/gadget.c
> > @@ -2423,6 +2423,7 @@ void dwc2_hsotg_core_init_disconnected(struct
> dwc2_hsotg *hsotg,
> >  	/* enable, but don't activate EP0in */
> >  	dwc2_writel(dwc2_hsotg_ep0_mps(hsotg->eps_out[0]-
> >ep.maxpacket) |
> >  	       DXEPCTL_USBACTEP, hsotg->regs + DIEPCTL0);
> > +	hsotg->eps_out[0]->enabled = 1;
> >
> >  	dwc2_hsotg_enqueue_setup(hsotg);
> >
> > @@ -2680,6 +2681,14 @@ static int dwc2_hsotg_ep_enable(struct usb_ep
> *ep,
> >  		return -EINVAL;
> >  	}
> >
> > +	spin_lock_irqsave(&hsotg->lock, flags);
> > +	if (hs_ep->enabled) {
> > +		dev_warn(hsotg->dev, "%s: ep %s already enabled\n",
> > +			__func__, hs_ep->name);
> 
> this is a rather serious condition. I'd rather use dev_WARN_ONCE():
> 
> 	if (dev_WARN_ONCE(hsotg->dev, hs_ep->enabled,
>            	"ep %s already enabled\n", hs_ep->name)) {
> 
> --
> balbi
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