Patch "usb: dwc3: omap: fix race of pm runtime with irq handler in probe" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

usb: dwc3: omap: fix race of pm runtime with irq handler in probe

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-dwc3-omap-fix-race-of-pm-runtime-with-irq-handler-in-probe.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Grygorii Strashko <[email protected]>
Date: Mon, 12 Dec 2016 13:37:52 -0600
Subject: usb: dwc3: omap: fix race of pm runtime with irq handler in probe

From: Grygorii Strashko <[email protected]>

[ Upstream commit 12a7f17fac5b370bec87259e4c718faf563ce900 ]

Now races can happen between interrupt handler execution and PM runtime in error handling code path in probe and in dwc3_omap_remove() which will lead to system crash:

in probe:
...
err1:

	pm_runtime_put_sync(dev);
^^ PM runtime can race with IRQ handler when deferred probing happening
   due to extcon
	pm_runtime_disable(dev);

	return ret;

in dwc3_omap_remove:
...

	dwc3_omap_disable_irqs(omap);
^^ IRQs are disabled in HW, but handler may still run
	of_platform_depopulate(omap->dev);
	pm_runtime_put_sync(&pdev->dev);
^^ PM runtime can race with IRQ handler
	pm_runtime_disable(&pdev->dev);

	return 0;

So, OMAP DWC3 IRQ need to be disabled before calling pm_runtime_put() in probe and in dwc3_omap_remove().

---
 drivers/usb/dwc3/dwc3-omap.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

@@ -19,6 +19,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
+#include <linux/irq.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/platform_data/dwc3-omap.h>

@@ -511,7 +512,7 @@ static int dwc3_omap_probe(struct platfo
 
 	/* check the DMA Status */
 	reg = dwc3_omap_readl(omap->base, USBOTGSS_SYSCONFIG);
-
+	irq_set_status_flags(omap->irq, IRQ_NOAUTOEN);
 	ret = devm_request_threaded_irq(dev, omap->irq, dwc3_omap_interrupt,
 					dwc3_omap_interrupt_thread, IRQF_SHARED,
 					"dwc3-omap", omap);

@@ -532,7 +533,7 @@ static int dwc3_omap_probe(struct platfo
 	}
 
 	dwc3_omap_enable_irqs(omap);
-
+	enable_irq(omap->irq);
 	return 0;
 
 err2:

@@ -553,6 +554,7 @@ static int dwc3_omap_remove(struct platf
 	extcon_unregister_notifier(omap->edev, EXTCON_USB, &omap->vbus_nb);
 	extcon_unregister_notifier(omap->edev, EXTCON_USB_HOST, &omap->id_nb);
 	dwc3_omap_disable_irqs(omap);
+	disable_irq(omap->irq);
 	of_platform_depopulate(omap->dev);
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/usb-dwc3-omap-fix-race-of-pm-runtime-with-irq-handler-in-probe.patch queue-4.9/irqchip-keystone-fix-scheduling-while-atomic-on-rt.patch