* wangbiao <biao.wang@xxxxxxxxx> wrote:
> @@ -86,6 +86,7 @@ static const char driver_name [] = "usbnet";
>
> /* use ethtool to change the level for any given device */
> static int msg_level = -1;
> +static spinlock_t dev_wait_lock = __SPIN_LOCK_UNLOCKED(dev_wait_lock);
> module_param (msg_level, int, 0);
> MODULE_PARM_DESC (msg_level, "Override default message level");
>
> @@ -1447,13 +1454,18 @@ static void usbnet_bh (unsigned long param)
> clear_bit(EVENT_RX_KILL, &dev->flags);
>
> // waiting for all pending urbs to complete?
Please escape this code from the clutches of C++ style!
> + spin_lock_irqsave(&dev_wait_lock, flags);
> if (dev->wait) {
> if ((dev->txq.qlen + dev->rxq.qlen + dev->done.qlen) == 0) {
> - wake_up (dev->wait);
> + wake_up(dev->wait);
> }
> + spin_unlock_irqrestore(&dev_wait_lock, flags);
> + return;
> + }
> + spin_unlock_irqrestore(&dev_wait_lock, flags);
The extra locking and the naked return from the middle of the
control flow is a bit sad.
>
> // or are we maybe short a few urbs?
> - } else if (netif_running (dev->net) &&
> + if (netif_running(dev->net) &&
> netif_device_present (dev->net) &&
> netif_carrier_ok(dev->net) &&
> !timer_pending (&dev->delay) &&
While using a global spinlock from the probe/teardown methods is
probably not a big deal, using it in usbnet_bh() looks rather
unfortunate for performance and scalability of this driver.
I don't know the usbnet code at all, but is there really no
natural per device synchronization method available for such
cases? Could the race be avoided some other way? How do other
drivers implement such kind of dev->wait handling?
Thanks,
Ingo
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