This is a note to let you know that I've just added the patch titled
USB: net2280: Fix erroneous synchronization change
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From dec3c23c9aa1815f07d98ae0375b4cbc10971e13 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Date: Wed, 8 Aug 2018 11:20:39 -0400
Subject: USB: net2280: Fix erroneous synchronization change
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@xxxxxxxxxxxxxxxxxxx>
Fixes: f16443a034c7 ("USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks")
Reported-by: D. Ziesche <dziesche@xxxxxxx>
Tested-by: D. Ziesche <dziesche@xxxxxxx>
CC: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
---
drivers/usb/gadget/udc/net2280.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/udc/net2280.c b/drivers/usb/gadget/udc/net2280.c
index 318246d8b2e2..b02ab2a8d927 100644
--- a/drivers/usb/gadget/udc/net2280.c
+++ b/drivers/usb/gadget/udc/net2280.c
@@ -1545,11 +1545,14 @@ 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;
}
@@ -2466,8 +2469,11 @@ 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);
}
@@ -3341,6 +3347,8 @@ static void handle_stat0_irqs(struct net2280 *dev, u32 stat)
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;
@@ -3381,12 +3389,14 @@ 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;
}
}
@@ -3405,6 +3415,7 @@ 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);
@@ -3415,6 +3426,7 @@ 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;
}
--
2.18.0
