From: Stanislaw Gruszka Date: Wed, 19 Feb 2014 09:29:01 +0000 (+0100) Subject: usb: ehci: fix deadlock when threadirqs option is used X-Git-Tag: firefly_0821_release~3679^2~2690 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2efc229a0ec1b247e8c2ca5069d22252e792333a;p=firefly-linux-kernel-4.4.55.git usb: ehci: fix deadlock when threadirqs option is used commit a1227f3c1030e96ebc51d677d2f636268845c5fb upstream. ehci_irq() and ehci_hrtimer_func() can deadlock on ehci->lock when threadirqs option is used. To prevent the deadlock use spin_lock_irqsave() in ehci_irq(). This change can be reverted when hrtimer callbacks become threaded. Signed-off-by: Stanislaw Gruszka Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index 246e124e6ac5..4518b8189a9e 100644 --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -686,8 +686,15 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd) struct ehci_hcd *ehci = hcd_to_ehci (hcd); u32 status, masked_status, pcd_status = 0, cmd; int bh; + unsigned long flags; - spin_lock (&ehci->lock); + /* + * For threadirqs option we use spin_lock_irqsave() variant to prevent + * deadlock with ehci hrtimer callback, because hrtimer callbacks run + * in interrupt context even when threadirqs is specified. We can go + * back to spin_lock() variant when hrtimer callbacks become threaded. + */ + spin_lock_irqsave(&ehci->lock, flags); status = ehci_readl(ehci, &ehci->regs->status); @@ -705,7 +712,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd) /* Shared IRQ? */ if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED)) { - spin_unlock(&ehci->lock); + spin_unlock_irqrestore(&ehci->lock, flags); return IRQ_NONE; } @@ -823,7 +830,7 @@ dead: if (bh) ehci_work (ehci); - spin_unlock (&ehci->lock); + spin_unlock_irqrestore(&ehci->lock, flags); if (pcd_status) usb_hcd_poll_rh_status(hcd); return IRQ_HANDLED;