| From a1227f3c1030e96ebc51d677d2f636268845c5fb Mon Sep 17 00:00:00 2001 |
| From: Stanislaw Gruszka <sgruszka@redhat.com> |
| Date: Wed, 19 Feb 2014 10:29:01 +0100 |
| Subject: usb: ehci: fix deadlock when threadirqs option is used |
| |
| From: Stanislaw Gruszka <sgruszka@redhat.com> |
| |
| 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 <sgruszka@redhat.com> |
| Acked-by: Alan Stern <stern@rowland.harvard.edu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/usb/host/ehci-hcd.c | 13 ++++++++++--- |
| 1 file changed, 10 insertions(+), 3 deletions(-) |
| |
| --- 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_ |
| 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_ |
| |
| /* 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; |