4.4-stable review patch. If anyone has any objections, please let me know.
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From: Alan Stern stern@rowland.harvard.edu
commit dec3c23c9aa1815f07d98ae0375b4cbc10971e13 upstream.
Commit f16443a034c7 ("USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks") was based on a serious misunderstanding. It introduced regressions into both the dummy-hcd and net2280 drivers.
The problem in dummy-hcd was fixed by commit 7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous synchronization change"), but the problem in net2280 remains. Namely: the ->disconnect(), ->suspend(), ->resume(), and ->reset() callbacks must be invoked without the private lock held; otherwise a deadlock will occur when the callback routine tries to interact with the UDC driver.
This patch largely is a reversion of the relevant parts of f16443a034c7. It also drops the private lock around the calls to ->suspend() and ->resume() (something the earlier patch forgot to do). This is safe from races with device interrupts because it occurs within the interrupt handler.
Finally, the patch changes where the ->disconnect() callback is invoked when net2280_pullup() turns the pullup off. Rather than making the callback from within stop_activity() at a time when dropping the private lock could be unsafe, the callback is moved to a point after the lock has already been dropped.
Signed-off-by: Alan Stern stern@rowland.harvard.edu Fixes: f16443a034c7 ("USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks") Reported-by: D. Ziesche dziesche@zes.com Tested-by: D. Ziesche dziesche@zes.com CC: stable@vger.kernel.org Signed-off-by: Felipe Balbi felipe.balbi@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/gadget/udc/net2280.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
--- a/drivers/usb/gadget/udc/net2280.c +++ b/drivers/usb/gadget/udc/net2280.c @@ -1542,11 +1542,14 @@ static int net2280_pullup(struct usb_gad writel(tmp | BIT(USB_DETECT_ENABLE), &dev->usb->usbctl); } else { writel(tmp & ~BIT(USB_DETECT_ENABLE), &dev->usb->usbctl); - stop_activity(dev, dev->driver); + stop_activity(dev, NULL); }
spin_unlock_irqrestore(&dev->lock, flags);
+ if (!is_on && dev->driver) + dev->driver->disconnect(&dev->gadget); + return 0; }
@@ -2425,8 +2428,11 @@ static void stop_activity(struct net2280 nuke(&dev->ep[i]);
/* report disconnect; the driver is already quiesced */ - if (driver) + if (driver) { + spin_unlock(&dev->lock); driver->disconnect(&dev->gadget); + spin_lock(&dev->lock); + }
usb_reinit(dev); } @@ -3272,6 +3278,8 @@ next_endpoints: BIT(PCI_RETRY_ABORT_INTERRUPT))
static void handle_stat1_irqs(struct net2280 *dev, u32 stat) +__releases(dev->lock) +__acquires(dev->lock) { struct net2280_ep *ep; u32 tmp, num, mask, scratch; @@ -3312,12 +3320,14 @@ static void handle_stat1_irqs(struct net if (disconnect || reset) { stop_activity(dev, dev->driver); ep0_start(dev); + spin_unlock(&dev->lock); if (reset) usb_gadget_udc_reset (&dev->gadget, dev->driver); else (dev->driver->disconnect) (&dev->gadget); + spin_lock(&dev->lock); return; } } @@ -3336,6 +3346,7 @@ static void handle_stat1_irqs(struct net tmp = BIT(SUSPEND_REQUEST_CHANGE_INTERRUPT); if (stat & tmp) { writel(tmp, &dev->regs->irqstat1); + spin_unlock(&dev->lock); if (stat & BIT(SUSPEND_REQUEST_INTERRUPT)) { if (dev->driver->suspend) dev->driver->suspend(&dev->gadget); @@ -3346,6 +3357,7 @@ static void handle_stat1_irqs(struct net dev->driver->resume(&dev->gadget); /* at high speed, note erratum 0133 */ } + spin_lock(&dev->lock); stat &= ~tmp; }