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Date: Thu, 11 Apr 2013 10:28:33 -0500
From: Dan Williams <dcbw@...hat.com>
To: Ming Lei <tom.leiming@...il.com>
Cc: Oliver Neukum <oliver@...kum.org>,
Elina Pasheva <epasheva@...rrawireless.com>,
Network Development <netdev@...r.kernel.org>,
linux-usb <linux-usb@...r.kernel.org>,
Rory Filer <rfiler@...rrawireless.com>,
Phil Sutter <phil@....cc>
Subject: Re: [PATCH 1/2 v5] usbnet: allow status interrupt URB to always be
active
On Thu, 2013-04-11 at 10:31 +0800, Ming Lei wrote:
> On Thu, Apr 11, 2013 at 4:30 AM, Dan Williams <dcbw@...hat.com> wrote:
> > Some drivers (sierra_net) need the status interrupt URB
> > active even when the device is closed, because they receive
> > custom indications from firmware. Add functions to refcount
> > the status interrupt URB submit/kill operation so that
> > sub-drivers and the generic driver don't fight over whether
> > the status interrupt URB is active or not.
> >
> > A sub-driver can call usbnet_status_start() at any time, but
> > the URB is only submitted the first time the function is
> > called. Likewise, when the sub-driver is done with the URB,
> > it calls usbnet_status_stop() but the URB is only killed when
> > all users have stopped it. The URB is still killed and
> > re-submitted for suspend/resume, as before, with the same
> > refcount it had at suspend.
> >
> > Signed-off-by: Dan Williams <dcbw@...hat.com>
> > ---
> > drivers/net/usb/usbnet.c | 79 ++++++++++++++++++++++++++++++++++++++++++----
> > include/linux/usb/usbnet.h | 5 +++
> > 2 files changed, 77 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
> > index 51f3192..b71ce36 100644
> > --- a/drivers/net/usb/usbnet.c
> > +++ b/drivers/net/usb/usbnet.c
> > @@ -252,6 +252,70 @@ static int init_status (struct usbnet *dev, struct usb_interface *intf)
> > return 0;
> > }
> >
> > +/* Submit the interrupt URB if not previously submitted, increasing refcount */
> > +int usbnet_status_start(struct usbnet *dev, gfp_t mem_flags)
>
> 'mem_flags' isn't needed any more since we can apply allocation
> of GFP_NOIO automatically in resume path now, and you can always
> use GFP_KERNEL safely. Considered that it is a API, please don't
> introduce it.
>
> After removing it, you can add
>
> Acked-by: Ming Lei <ming.lei@...onical.com>
>
> > +{
> > + int ret = 0;
> > +
> > + WARN_ON_ONCE(dev->interrupt == NULL);
> > + if (dev->interrupt) {
> > + mutex_lock(&dev->interrupt_mutex);
> > +
> > + if (++dev->interrupt_count == 1)
> > + ret = usb_submit_urb(dev->interrupt, mem_flags);
> > +
> > + dev_dbg(&dev->udev->dev, "incremented interrupt URB count to %d\n",
> > + dev->interrupt_count);
> > + mutex_unlock(&dev->interrupt_mutex);
> > + }
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(usbnet_status_start);
> > +
> > +/* For resume; submit interrupt URB if previously submitted */
> > +static int __usbnet_status_start_force(struct usbnet *dev, gfp_t mem_flags)
> > +{
> > + int ret = 0;
> > +
> > + mutex_lock(&dev->interrupt_mutex);
> > + if (dev->interrupt_count) {
> > + ret = usb_submit_urb(dev->interrupt, mem_flags);
> > + dev_dbg(&dev->udev->dev,
> > + "submitted interrupt URB for resume\n");
> > + }
> > + mutex_unlock(&dev->interrupt_mutex);
> > + return ret;
> > +}
> > +
> > +/* Kill the interrupt URB if all submitters want it killed */
> > +void usbnet_status_stop(struct usbnet *dev)
> > +{
> > + if (dev->interrupt) {
> > + mutex_lock(&dev->interrupt_mutex);
> > + WARN_ON(dev->interrupt_count == 0);
> > +
> > + if (dev->interrupt_count && --dev->interrupt_count == 0)
> > + usb_kill_urb(dev->interrupt);
> > +
> > + dev_dbg(&dev->udev->dev,
> > + "decremented interrupt URB count to %d\n",
> > + dev->interrupt_count);
> > + mutex_unlock(&dev->interrupt_mutex);
> > + }
> > +}
> > +EXPORT_SYMBOL_GPL(usbnet_status_stop);
> > +
> > +/* For suspend; always kill interrupt URB */
> > +static void __usbnet_status_stop_force(struct usbnet *dev)
> > +{
> > + if (dev->interrupt) {
> > + mutex_lock(&dev->interrupt_mutex);
> > + usb_kill_urb(dev->interrupt);
> > + dev_dbg(&dev->udev->dev, "killed interrupt URB for suspend\n");
> > + mutex_unlock(&dev->interrupt_mutex);
> > + }
> > +}
>
> Looks it isn't a good practice to duplicate code in above four functions, but
> it should be OK to merge first.
Oliver requested this approach. I'd originally taken your suggestion to
merge them, but this proved somewhat more complicated and Oliver
rejected that approach.
Dan
> > +
> > /* Passes this packet up the stack, updating its accounting.
> > * Some link protocols batch packets, so their rx_fixup paths
> > * can return clones as well as just modify the original skb.
> > @@ -725,7 +789,7 @@ int usbnet_stop (struct net_device *net)
> > if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
> > usbnet_terminate_urbs(dev);
> >
> > - usb_kill_urb(dev->interrupt);
> > + usbnet_status_stop(dev);
> >
> > usbnet_purge_paused_rxq(dev);
> >
> > @@ -787,7 +851,7 @@ int usbnet_open (struct net_device *net)
> >
> > /* start any status interrupt transfer */
> > if (dev->interrupt) {
> > - retval = usb_submit_urb (dev->interrupt, GFP_KERNEL);
> > + retval = usbnet_status_start(dev, GFP_KERNEL);
> > if (retval < 0) {
> > netif_err(dev, ifup, dev->net,
> > "intr submit %d\n", retval);
> > @@ -1430,6 +1494,8 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
> > dev->delay.data = (unsigned long) dev;
> > init_timer (&dev->delay);
> > mutex_init (&dev->phy_mutex);
> > + mutex_init(&dev->interrupt_mutex);
> > + dev->interrupt_count = 0;
> >
> > dev->net = net;
> > strcpy (net->name, "usb%d");
> > @@ -1565,7 +1631,7 @@ int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
> > */
> > netif_device_detach (dev->net);
> > usbnet_terminate_urbs(dev);
> > - usb_kill_urb(dev->interrupt);
> > + __usbnet_status_stop_force(dev);
> >
> > /*
> > * reattach so runtime management can use and
> > @@ -1585,9 +1651,8 @@ int usbnet_resume (struct usb_interface *intf)
> > int retval;
> >
> > if (!--dev->suspend_count) {
> > - /* resume interrupt URBs */
> > - if (dev->interrupt && test_bit(EVENT_DEV_OPEN, &dev->flags))
> > - usb_submit_urb(dev->interrupt, GFP_NOIO);
> > + /* resume interrupt URB if it was previously submitted */
> > + __usbnet_status_start_force(dev, GFP_NOIO);
> >
> > spin_lock_irq(&dev->txq.lock);
> > while ((res = usb_get_from_anchor(&dev->deferred))) {
> > diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
> > index 0e5ac93..d71f44c 100644
> > --- a/include/linux/usb/usbnet.h
> > +++ b/include/linux/usb/usbnet.h
> > @@ -56,6 +56,8 @@ struct usbnet {
> > struct sk_buff_head done;
> > struct sk_buff_head rxq_pause;
> > struct urb *interrupt;
> > + unsigned interrupt_count;
> > + struct mutex interrupt_mutex;
> > struct usb_anchor deferred;
> > struct tasklet_struct bh;
> >
> > @@ -246,4 +248,7 @@ extern int usbnet_nway_reset(struct net_device *net);
> >
> > extern int usbnet_manage_power(struct usbnet *, int);
> >
> > +int usbnet_status_start(struct usbnet *dev, gfp_t mem_flags);
> > +void usbnet_status_stop(struct usbnet *dev);
> > +
> > #endif /* __LINUX_USB_USBNET_H */
> > --
> > 1.8.1.4
> >
> >
>
>
> Thanks,
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