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authorStanislaw Gruszka <sgruszka@redhat.com>2014-02-19 10:29:01 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-03-06 21:30:10 -0800
commit2efc229a0ec1b247e8c2ca5069d22252e792333a (patch)
tree26a54af9ced0a7205a1b90df4465549d720c9117
parent9021ee52db43b0966d04d75b28a8c9e07362df49 (diff)
downloadlinux-linaro-stable-2efc229a0ec1b247e8c2ca5069d22252e792333a.tar.gz
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 <sgruszka@redhat.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/usb/host/ehci-hcd.c13
1 files changed, 10 insertions, 3 deletions
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;