[PATCH] usb: dwc3: omap: remove devm_request_threaded_irq

Grygorii Strashko
2016-12-09T20:55:08Z

Switch back from devm_request_threaded_irq() to request_threaded_irq() to
avoid races between interrupt handler execution and PM runtime in error
handling code path in probe and in dwc3_omap_remove():

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 end freed before calling
pm_runtime_put() in probe and in dwc3_omap_remove().

Signed-off-by: Grygorii Strashko <grygorii.strashko-l0cyMroinI0@public.gmane.org>
---
Hi Tony,

This is reworked patch, so might be it need to be re-tested.

drivers/usb/dwc3/dwc3-omap.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/dwc3/dwc3-omap.c b/drivers/usb/dwc3/dwc3-omap.c
index 29e80cc..79d74f6 100644
--- a/drivers/usb/dwc3/dwc3-omap.c
+++ b/drivers/usb/dwc3/dwc3-omap.c
@@ -511,18 +511,18 @@ static int dwc3_omap_probe(struct platform_device *pdev)
/* check the DMA Status */
reg = dwc3_omap_readl(omap->base, USBOTGSS_SYSCONFIG);

- ret = devm_request_threaded_irq(dev, omap->irq, dwc3_omap_interrupt,
- dwc3_omap_interrupt_thread, IRQF_SHARED,
- "dwc3-omap", omap);
+ ret = request_threaded_irq(omap->irq, dwc3_omap_interrupt,
+ dwc3_omap_interrupt_thread, IRQF_SHARED,
+ "dwc3-omap", omap);
if (ret) {
dev_err(dev, "failed to request IRQ #%d --> %d\n",
omap->irq, ret);
- goto err1;
+ goto err11;
}

ret = dwc3_omap_extcon_register(omap);
if (ret < 0)
- goto err1;
+ goto err11;

ret = of_platform_populate(node, NULL, NULL, dev);
if (ret) {
@@ -538,6 +538,8 @@ static int dwc3_omap_probe(struct platform_device *pdev)
extcon_unregister_notifier(omap->edev, EXTCON_USB, &omap->vbus_nb);
extcon_unregister_notifier(omap->edev, EXTCON_USB_HOST, &omap->id_nb);

+err11:
+ free_irq(omap->irq, omap);
err1:
pm_runtime_put_sync(dev);
pm_runtime_disable(dev);
@@ -552,6 +554,7 @@ static int dwc3_omap_remove(struct platform_device *pdev)
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);
+ free_irq(omap->irq, omap);
of_platform_depopulate(omap->dev);
pm_runtime_put_sync(&pdev->dev);
pm_runtime_disable(&pdev->dev);
--
2.10.1