[kernel/f19] Fix lockdep issue in EHCI when using threaded IRQs (rhbz 1056170)

[Josh Boyer]

commit c8c3b3265b8d6c36917066d06f8e280ba970d772
Author: Josh Boyer <jwboyer at redhat.com>
Date:   Mon Feb 24 11:09:22 2014 -0500

    Fix lockdep issue in EHCI when using threaded IRQs (rhbz 1056170)

 kernel.spec                                        |    9 +++
 ...x-deadlock-when-threadirqs-option-is-used.patch |   57 ++++++++++++++++++++
 2 files changed, 66 insertions(+), 0 deletions(-)
---
diff --git a/kernel.spec b/kernel.spec
index fbcf2d4..c1205a1 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -767,6 +767,9 @@ Patch25203: cpufreq-powernow-k8-Initialize-per-cpu-data-structures-properly.patc
 #rhbz 994438
 Patch25024: e100-Fix-disabling-already-disabled-device-warning.patch
 
+#rhbz 1056170
+Patch25025: usb-ehci-fix-deadlock-when-threadirqs-option-is-used.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -1480,6 +1483,9 @@ ApplyPatch cpufreq-powernow-k8-Initialize-per-cpu-data-structures-properly.patch
 #rhbz 994438
 ApplyPatch e100-Fix-disabling-already-disabled-device-warning.patch
 
+#rhbz 1056170
+ApplyPatch usb-ehci-fix-deadlock-when-threadirqs-option-is-used.patch
+
 
 # END OF PATCH APPLICATIONS
 
@@ -2293,6 +2299,9 @@ fi
 # and build.
 
 %changelog
+* Mon Feb 24 2014 Josh Boyer <jwboyer at fedoraproject.org>
+- Fix lockdep issue in EHCI when using threaded IRQs (rhbz 1056170)
+
 * Mon Feb 24 2014 Justin M. Forbes <jforbes at fedoraproject.org>
 - Linux v3.13.5
 
diff --git a/usb-ehci-fix-deadlock-when-threadirqs-option-is-used.patch b/usb-ehci-fix-deadlock-when-threadirqs-option-is-used.patch
new file mode 100644
index 0000000..9593c14
--- /dev/null
+++ b/usb-ehci-fix-deadlock-when-threadirqs-option-is-used.patch
@@ -0,0 +1,57 @@
+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 at redhat.com>
+---
+ drivers/usb/host/ehci-hcd.c | 13 ++++++++++---
+ 1 file changed, 10 insertions(+), 3 deletions(-)
+
+diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
+index 4711427..0bc6410 100644
+--- a/drivers/usb/host/ehci-hcd.c
++++ b/drivers/usb/host/ehci-hcd.c
+@@ -685,8 +685,15 @@ 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);
+ 
+@@ -704,7 +711,7 @@ 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;
+ 	}
+ 
+@@ -815,7 +822,7 @@ 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;
+-- 
+1.7.11.7
+
+--
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