diff options
| author | Stanislaw Gruszka <sgruszka@redhat.com> | 2014-02-19 10:29:01 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-03-06 22:06:24 -0800 |
| commit | 9995c904987d740b0457317b1d8c08968af7263a (patch) | |
| tree | f6682c7684b313faf2364403ad95c8825ebf7c26 | |
| parent | aa0346d71ecec4b91cd48d35fcaa992c986a38ed (diff) | |
| download | lwn-9995c904987d740b0457317b1d8c08968af7263a.tar.gz lwn-9995c904987d740b0457317b1d8c08968af7263a.zip | |
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.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index e8ba4c44223a..4dfd6fbad2be 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; |