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usb: ehci: fix deadlock when threadirqs option is used

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commit a1227f3c10 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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Stanislaw Gruszka 2014-02-19 10:29:01 +01:00 committed by Ben Hutchings
parent 05e327077e
commit 0986dc71fb
1 changed files with 10 additions and 3 deletions
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13
drivers/usb/host/ehci-hcd.c
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@ -807,8 +807,15 @@ 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);
@ -826,7 +833,7 @@ 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;
}
@ -929,7 +936,7 @@ 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;