Re: [PATCH] usb: dwc2: Revert "usb: dwc2: Disable all EP's on disconnect"

Dan Carpenter
2018-12-04T13:29:53Z

On Tue, Dec 04, 2018 at 12:34:08PM +0000, Minas Harutyunyan wrote:
> @@ -3185,12 +3183,13 @@ void dwc2_hsotg_disconnect(struct dwc2_hsotg *hsotg)
> hsotg->connected = 0;
> hsotg->test_mode = 0;
>
> - /* all endpoints should be shutdown */
> for (ep = 0; ep < hsotg->num_of_eps; ep++) {
> if (hsotg->eps_in[ep])
> - dwc2_hsotg_ep_disable(&hsotg->eps_in[ep]->ep);
> + kill_all_requests(hsotg, hsotg->eps_in[ep],
> + -ESHUTDOWN);
> if (hsotg->eps_out[ep])
> - dwc2_hsotg_ep_disable(&hsotg->eps_out[ep]->ep);
> + kill_all_requests(hsotg, hsotg->eps_out[ep],
> + -ESHUTDOWN);

Should this part be in a separate patch?

I'm not trying to be rhetorical at all. I literally don't know the
code very well. Hopefully the full commit message will explain it.

> }
>
> call_gadget(hsotg, disconnect);
> @@ -3234,6 +3233,8 @@ static void dwc2_hsotg_irq_fifoempty(struct
> dwc2_hsotg *hsotg, bool periodic)
> GINTSTS_PTXFEMP | \
> GINTSTS_RXFLVL)
>
> +static int dwc2_hsotg_ep_disable(struct usb_ep *ep);
> +
> /**
> * dwc2_hsotg_core_init - issue softreset to the core
> * @hsotg: The device state
> @@ -3258,12 +3259,14 @@ void dwc2_hsotg_core_init_disconnected(struct
> dwc2_hsotg *hsotg,
> return;
> } else {
> /* all endpoints should be shutdown */
> + spin_unlock(&hsotg->lock);
> for (ep = 1; ep < hsotg->num_of_eps; ep++) {
> if (hsotg->eps_in[ep])
>
> dwc2_hsotg_ep_disable(&hsotg->eps_in[ep]->ep);
> if (hsotg->eps_out[ep])
>
> dwc2_hsotg_ep_disable(&hsotg->eps_out[ep]->ep);
> }
> + spin_lock(&hsotg->lock);
> }
>
> /*

The idea here is that this is the only caller which is holding the
lock and we drop it here and take it again inside dwc2_hsotg_ep_disable().
I don't know the code very well and can't totally swear that this
doesn't introduce a small race condition...

Another option would be to introduce a new function which takes the lock
and change all the other callers instead. To me that would be easier to
review... See below for how it might look:

regards,
dan carpenter

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 94f3ba995580..b17a5dbefd5f 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -3166,6 +3166,7 @@ static void kill_all_requests(struct dwc2_hsotg *hsotg,
}

static int dwc2_hsotg_ep_disable(struct usb_ep *ep);
+static int dwc2_hsotg_ep_disable_lock(struct usb_ep *ep);

/**
* dwc2_hsotg_disconnect - disconnect service
@@ -3188,9 +3189,9 @@ void dwc2_hsotg_disconnect(struct dwc2_hsotg *hsotg)
/* all endpoints should be shutdown */
for (ep = 0; ep < hsotg->num_of_eps; ep++) {
if (hsotg->eps_in[ep])
- dwc2_hsotg_ep_disable(&hsotg->eps_in[ep]->ep);
+ dwc2_hsotg_ep_disable_lock(&hsotg->eps_in[ep]->ep);
if (hsotg->eps_out[ep])
- dwc2_hsotg_ep_disable(&hsotg->eps_out[ep]->ep);
+ dwc2_hsotg_ep_disable_lock(&hsotg->eps_out[ep]->ep);
}

call_gadget(hsotg, disconnect);
@@ -4069,10 +4070,8 @@ static int dwc2_hsotg_ep_disable(struct usb_ep *ep)
struct dwc2_hsotg *hsotg = hs_ep->parent;
int dir_in = hs_ep->dir_in;
int index = hs_ep->index;
- unsigned long flags;
u32 epctrl_reg;
u32 ctrl;
- int locked;

dev_dbg(hsotg->dev, "%s(ep %p)\n", __func__, ep);

@@ -4088,10 +4087,6 @@ static int dwc2_hsotg_ep_disable(struct usb_ep *ep)

epctrl_reg = dir_in ? DIEPCTL(index) : DOEPCTL(index);

- locked = spin_is_locked(&hsotg->lock);
- if (!locked)
- spin_lock_irqsave(&hsotg->lock, flags);
-
ctrl = dwc2_readl(hsotg, epctrl_reg);

if (ctrl & DXEPCTL_EPENA)
@@ -4114,12 +4109,23 @@ static int dwc2_hsotg_ep_disable(struct usb_ep *ep)
hs_ep->fifo_index = 0;
hs_ep->fifo_size = 0;

- if (!locked)
- spin_unlock_irqrestore(&hsotg->lock, flags);
-
return 0;
}

+static int dwc2_hsotg_ep_disable_lock(struct usb_ep *ep)
+{
+ struct dwc2_hsotg_ep *hs_ep = our_ep(ep);
+ struct dwc2_hsotg *hsotg = hs_ep->parent;
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&hsotg->lock, flags);
+ ret = dwc2_hsotg_ep_disable(ep);
+ spin_unlock_irqrestore(&hsotg->lock, flags);
+
+ return ret;
+}
+
/**
* on_list - check request is on the given endpoint
* @ep: The endpoint to check.
@@ -4267,7 +4273,7 @@ static int dwc2_hsotg_ep_sethalt_lock(struct usb_ep *ep, int value)

static const struct usb_ep_ops dwc2_hsotg_ep_ops = {
.enable = dwc2_hsotg_ep_enable,
- .disable = dwc2_hsotg_ep_disable,
+ .disable = dwc2_hsotg_ep_disable_lock,
.alloc_request = dwc2_hsotg_ep_alloc_request,
.free_request = dwc2_hsotg_ep_free_request,
.queue = dwc2_hsotg_ep_queue_lock,
@@ -4407,9 +4413,9 @@ static int dwc2_hsotg_udc_stop(struct usb_gadget *gadget)
/* all endpoints should be shutdown */
for (ep = 1; ep < hsotg->num_of_eps; ep++) {
if (hsotg->eps_in[ep])
- dwc2_hsotg_ep_disable(&hsotg->eps_in[ep]->ep);
+ dwc2_hsotg_ep_disable_lock(&hsotg->eps_in[ep]->ep);
if (hsotg->eps_out[ep])
- dwc2_hsotg_ep_disable(&hsotg->eps_out[ep]->ep);
+ dwc2_hsotg_ep_disable_lock(&hsotg->eps_out[ep]->ep);
}

spin_lock_irqsave(&hsotg->lock, flags);
@@ -4857,9 +4863,9 @@ int dwc2_hsotg_suspend(struct dwc2_hsotg *hsotg)

for (ep = 0; ep < hsotg->num_of_eps; ep++) {
if (hsotg->eps_in[ep])
- dwc2_hsotg_ep_disable(&hsotg->eps_in[ep]->ep);
+ dwc2_hsotg_ep_disable_lock(&hsotg->eps_in[ep]->ep);
if (hsotg->eps_out[ep])
- dwc2_hsotg_ep_disable(&hsotg->eps_out[ep]->ep);
+ dwc2_hsotg_ep_disable_lock(&hsotg->eps_out[ep]->ep);
}
}