From: Alan Stern Date: Wed, 8 Aug 2018 15:20:39 +0000 (-0400) Subject: USB: net2280: Fix erroneous synchronization change X-Git-Tag: v4.14.72~76 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d078f295a4c9159a52c63efca70da293cab0e4db;p=platform%2Fkernel%2Flinux-rpi.git USB: net2280: Fix erroneous synchronization change 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 Fixes: f16443a034c7 ("USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks") Reported-by: D. Ziesche Tested-by: D. Ziesche CC: Signed-off-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/gadget/udc/net2280.c b/drivers/usb/gadget/udc/net2280.c index f608c1f..9cbb061 100644 --- a/drivers/usb/gadget/udc/net2280.c +++ b/drivers/usb/gadget/udc/net2280.c @@ -1549,11 +1549,14 @@ static int net2280_pullup(struct usb_gadget *_gadget, int is_on) 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; } @@ -2470,8 +2473,11 @@ static void stop_activity(struct net2280 *dev, struct usb_gadget_driver *driver) 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); } @@ -3345,6 +3351,8 @@ 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; @@ -3385,12 +3393,14 @@ static void handle_stat1_irqs(struct net2280 *dev, u32 stat) 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; } } @@ -3409,6 +3419,7 @@ static void handle_stat1_irqs(struct net2280 *dev, u32 stat) 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); @@ -3419,6 +3430,7 @@ static void handle_stat1_irqs(struct net2280 *dev, u32 stat) dev->driver->resume(&dev->gadget); /* at high speed, note erratum 0133 */ } + spin_lock(&dev->lock); stat &= ~tmp; }