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usb: dwc3: omap: remove devm_request_threaded_irq

PATCH New Grygorii Strashko 2 participants 7 messages Dec 9, 2016

Subsystems (3)
USB DesignWare USB3 DRD IP driver OMAP USB support
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Grygorii Strashko

author
#0 lore raw

PATCH 1/1 usb: dwc3: omap: remove devm_request_threaded_irq

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 <[email protected]>

---
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(-)
drivers/usb/dwc3/dwc3-omap.c +8 -5
index 29e80cc..79d74f6 100644
@@ -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);
Signature · 1 line
2.10.1
#1 lore raw

PATCH 1/1 usb: dwc3: omap: remove devm_request_threaded_irq

Quoted 3 lines · Grygorii Strashko

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():

Can't you just call disable_irq() on the exit path instead of removing devm?

Regards,

Tony

author
#2 lore raw

PATCH 1/1 usb: dwc3: omap: remove devm_request_threaded_irq

Quoted 8 lines · Tony Lindgren
Quoted 3 lines · Grygorii Strashko

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():

Can't you just call disable_irq() on the exit path instead of removing devm?

I can. But what will be the benefit from using devm then?

Signature · 2 lines
regards,
-grygorii
#3 lore raw

PATCH 1/1 usb: dwc3: omap: remove devm_request_threaded_irq

Quoted 8 lines · Grygorii Strashko
Quoted 5 lines · Tony Lindgren
Quoted 3 lines · Grygorii Strashko

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():

Quoted 5 lines
Quoted 3 lines

Can't you just call disable_irq() on the exit path instead of removing devm?

I can. But what will be the benefit from using devm then?

Hmm good point. Probably the least number of code would be to just do NOAUTOEN before devm_request_irq(), then only do enable_irq() just before returning from the probe. After all, we don't really want the irq running until the probe is done.

I think that would leave out the extra handling from the error path?

Regards,

Tony

author
#4 lore raw

PATCH 1/1 usb: dwc3: omap: remove devm_request_threaded_irq

Quoted 15 lines · Tony Lindgren
Quoted 8 lines · Grygorii Strashko
Quoted 5 lines · Tony Lindgren
Quoted 3 lines · Grygorii Strashko

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():

Quoted 5 lines
Quoted 3 lines

Can't you just call disable_irq() on the exit path instead of removing devm?

I can. But what will be the benefit from using devm then?

Quoted 8 lines

Hmm good point. Probably the least number of code would be to just do NOAUTOEN before devm_request_irq(), then only do enable_irq() just before returning from the probe. After all, we don't really want the irq running until the probe is done.

I think that would leave out the extra handling from the error path?

Good question here is - do we need this irq to be enabled for sub-device probing from of_platform_populate()? ;)

Signature · 2 lines
regards,
-grygorii
#5 lore raw

PATCH 1/1 usb: dwc3: omap: remove devm_request_threaded_irq

Quoted 23 lines · Grygorii Strashko
Quoted 20 lines · Tony Lindgren
Quoted 8 lines · Grygorii Strashko
Quoted 5 lines · Tony Lindgren
Quoted 3 lines · Grygorii Strashko

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():

Quoted 5 lines
Quoted 3 lines

Can't you just call disable_irq() on the exit path instead of removing devm?

I can. But what will be the benefit from using devm then?

Hmm good point. Probably the least number of code would be to just do NOAUTOEN before devm_request_irq(), then only do enable_irq() just before returning from the probe. After all, we don't really want the irq running until the probe is done.

Quoted 6 lines
Quoted 3 lines

I think that would leave out the extra handling from the error path?

Good question here is - do we need this irq to be enabled for sub-device probing from of_platform_populate()? ;)

No!

Tony

author
#6 lore raw

PATCH 1/1 usb: dwc3: omap: remove devm_request_threaded_irq

Quoted 24 lines · Tony Lindgren
Quoted 23 lines · Grygorii Strashko
Quoted 20 lines · Tony Lindgren
Quoted 8 lines · Grygorii Strashko
Quoted 5 lines · Tony Lindgren
Quoted 3 lines · Grygorii Strashko

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():

Quoted 5 lines
Quoted 3 lines

Can't you just call disable_irq() on the exit path instead of removing devm?

I can. But what will be the benefit from using devm then?

Hmm good point. Probably the least number of code would be to just do NOAUTOEN before devm_request_irq(), then only do enable_irq() just before returning from the probe. After all, we don't really want the irq running until the probe is done.

Quoted 8 lines
Quoted 6 lines
Quoted 3 lines

I think that would leave out the extra handling from the error path?

Good question here is - do we need this irq to be enabled for sub-device probing from of_platform_populate()? ;)

No!

Ok, then it should work this way.

Signature · 2 lines
regards,
-grygorii