| Message ID | 20220804151001.23612-5-johan+linaro@kernel.org |
|---|---|
| State | Accepted |
| Commit | a872ab303d5ddd4c965f9cd868677781a33ce35a |
| Headers | show |
| Series | usb: dwc3: qcom: fix wakeup implementation | expand |
On Thu, Aug 04, 2022 at 05:09:56PM +0200, Johan Hovold wrote: > The Qualcomm dwc3 runtime-PM implementation checks the xhci > platform-device pointer in the wakeup-interrupt handler to determine > whether the controller is in host mode and if so triggers a resume. > > After a role switch in OTG mode the xhci platform-device would have been > freed and the next wakeup from runtime suspend would access the freed > memory. > > Note that role switching is executed from a freezable workqueue, which > guarantees that the pointer is stable during suspend. > > Also note that runtime PM has been broken since commit 2664deb09306 > ("usb: dwc3: qcom: Honor wakeup enabled/disabled state"), which > incidentally also prevents this issue from being triggered. > > Fixes: a4333c3a6ba9 ("usb: dwc3: Add Qualcomm DWC3 glue driver") > Cc: stable@vger.kernel.org # 4.18 > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> It'd be good to mention the introduction of dwc3_qcom_is_host() function. Initially I thought it is used in a single place, but going through the rest of the patches reveals that it is used later on. Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> Thanks, Mani > --- > > Changes in v2 > - new patch > > drivers/usb/dwc3/dwc3-qcom.c | 14 +++++++++++++- > drivers/usb/dwc3/host.c | 1 + > 2 files changed, 14 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c > index e9364141661b..6884026b9fad 100644 > --- a/drivers/usb/dwc3/dwc3-qcom.c > +++ b/drivers/usb/dwc3/dwc3-qcom.c > @@ -298,6 +298,14 @@ static void dwc3_qcom_interconnect_exit(struct dwc3_qcom *qcom) > icc_put(qcom->icc_path_apps); > } > > +/* Only usable in contexts where the role can not change. */ > +static bool dwc3_qcom_is_host(struct dwc3_qcom *qcom) > +{ > + struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3); > + > + return dwc->xhci; > +} > + > static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom) > { > struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3); > @@ -460,7 +468,11 @@ static irqreturn_t qcom_dwc3_resume_irq(int irq, void *data) > if (qcom->pm_suspended) > return IRQ_HANDLED; > > - if (dwc->xhci) > + /* > + * This is safe as role switching is done from a freezable workqueue > + * and the wakeup interrupts are disabled as part of resume. > + */ > + if (dwc3_qcom_is_host(qcom)) > pm_runtime_resume(&dwc->xhci->dev); > > return IRQ_HANDLED; > diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c > index f56c30cf151e..f6f13e7f1ba1 100644 > --- a/drivers/usb/dwc3/host.c > +++ b/drivers/usb/dwc3/host.c > @@ -135,4 +135,5 @@ int dwc3_host_init(struct dwc3 *dwc) > void dwc3_host_exit(struct dwc3 *dwc) > { > platform_device_unregister(dwc->xhci); > + dwc->xhci = NULL; > } > -- > 2.35.1 >
On Sat, Aug 06, 2022 at 08:03:11PM +0530, Manivannan Sadhasivam wrote: > On Thu, Aug 04, 2022 at 05:09:56PM +0200, Johan Hovold wrote: > > The Qualcomm dwc3 runtime-PM implementation checks the xhci > > platform-device pointer in the wakeup-interrupt handler to determine > > whether the controller is in host mode and if so triggers a resume. > > > > After a role switch in OTG mode the xhci platform-device would have been > > freed and the next wakeup from runtime suspend would access the freed > > memory. > > > > Note that role switching is executed from a freezable workqueue, which > > guarantees that the pointer is stable during suspend. > > > > Also note that runtime PM has been broken since commit 2664deb09306 > > ("usb: dwc3: qcom: Honor wakeup enabled/disabled state"), which > > incidentally also prevents this issue from being triggered. > > > > Fixes: a4333c3a6ba9 ("usb: dwc3: Add Qualcomm DWC3 glue driver") > > Cc: stable@vger.kernel.org # 4.18 > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > > It'd be good to mention the introduction of dwc3_qcom_is_host() function. > Initially I thought it is used in a single place, but going through the rest of > the patches reveals that it is used later on. I think the helper is warranted on its own as it serves as documentation of the underlying assumptions that this code relies on. > > +/* Only usable in contexts where the role can not change. */ > > +static bool dwc3_qcom_is_host(struct dwc3_qcom *qcom) > > +{ > > + struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3); > > + > > + return dwc->xhci; > > +} > > + > > static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom) > > { > > struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3); > > @@ -460,7 +468,11 @@ static irqreturn_t qcom_dwc3_resume_irq(int irq, void *data) > > if (qcom->pm_suspended) > > return IRQ_HANDLED; > > > > - if (dwc->xhci) > > + /* > > + * This is safe as role switching is done from a freezable workqueue > > + * and the wakeup interrupts are disabled as part of resume. > > + */ > > + if (dwc3_qcom_is_host(qcom)) > > pm_runtime_resume(&dwc->xhci->dev); > > > > return IRQ_HANDLED; > > diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c > > index f56c30cf151e..f6f13e7f1ba1 100644 > > --- a/drivers/usb/dwc3/host.c > > +++ b/drivers/usb/dwc3/host.c > > @@ -135,4 +135,5 @@ int dwc3_host_init(struct dwc3 *dwc) > > void dwc3_host_exit(struct dwc3 *dwc) > > { > > platform_device_unregister(dwc->xhci); > > + dwc->xhci = NULL; > > } > > -- > > 2.35.1 Johan
On Sat, Aug 06, 2022 at 06:08:51PM +0200, Johan Hovold wrote: > On Sat, Aug 06, 2022 at 08:03:11PM +0530, Manivannan Sadhasivam wrote: > > On Thu, Aug 04, 2022 at 05:09:56PM +0200, Johan Hovold wrote: > > > The Qualcomm dwc3 runtime-PM implementation checks the xhci > > > platform-device pointer in the wakeup-interrupt handler to determine > > > whether the controller is in host mode and if so triggers a resume. > > > > > > After a role switch in OTG mode the xhci platform-device would have been > > > freed and the next wakeup from runtime suspend would access the freed > > > memory. > > > > > > Note that role switching is executed from a freezable workqueue, which > > > guarantees that the pointer is stable during suspend. > > > > > > Also note that runtime PM has been broken since commit 2664deb09306 > > > ("usb: dwc3: qcom: Honor wakeup enabled/disabled state"), which > > > incidentally also prevents this issue from being triggered. > > > > > > Fixes: a4333c3a6ba9 ("usb: dwc3: Add Qualcomm DWC3 glue driver") > > > Cc: stable@vger.kernel.org # 4.18 > > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > > > > It'd be good to mention the introduction of dwc3_qcom_is_host() function. > > Initially I thought it is used in a single place, but going through the rest of > > the patches reveals that it is used later on. > > I think the helper is warranted on its own as it serves as documentation > of the underlying assumptions that this code relies on. > That's even better. Thanks, Mani > > > +/* Only usable in contexts where the role can not change. */ > > > +static bool dwc3_qcom_is_host(struct dwc3_qcom *qcom) > > > +{ > > > + struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3); > > > + > > > + return dwc->xhci; > > > +} > > > + > > > static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom) > > > { > > > struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3); > > > @@ -460,7 +468,11 @@ static irqreturn_t qcom_dwc3_resume_irq(int irq, void *data) > > > if (qcom->pm_suspended) > > > return IRQ_HANDLED; > > > > > > - if (dwc->xhci) > > > + /* > > > + * This is safe as role switching is done from a freezable workqueue > > > + * and the wakeup interrupts are disabled as part of resume. > > > + */ > > > + if (dwc3_qcom_is_host(qcom)) > > > pm_runtime_resume(&dwc->xhci->dev); > > > > > > return IRQ_HANDLED; > > > diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c > > > index f56c30cf151e..f6f13e7f1ba1 100644 > > > --- a/drivers/usb/dwc3/host.c > > > +++ b/drivers/usb/dwc3/host.c > > > @@ -135,4 +135,5 @@ int dwc3_host_init(struct dwc3 *dwc) > > > void dwc3_host_exit(struct dwc3 *dwc) > > > { > > > platform_device_unregister(dwc->xhci); > > > + dwc->xhci = NULL; > > > } > > > -- > > > 2.35.1 > > Johan
diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c index e9364141661b..6884026b9fad 100644 --- a/drivers/usb/dwc3/dwc3-qcom.c +++ b/drivers/usb/dwc3/dwc3-qcom.c @@ -298,6 +298,14 @@ static void dwc3_qcom_interconnect_exit(struct dwc3_qcom *qcom) icc_put(qcom->icc_path_apps); } +/* Only usable in contexts where the role can not change. */ +static bool dwc3_qcom_is_host(struct dwc3_qcom *qcom) +{ + struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3); + + return dwc->xhci; +} + static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom) { struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3); @@ -460,7 +468,11 @@ static irqreturn_t qcom_dwc3_resume_irq(int irq, void *data) if (qcom->pm_suspended) return IRQ_HANDLED; - if (dwc->xhci) + /* + * This is safe as role switching is done from a freezable workqueue + * and the wakeup interrupts are disabled as part of resume. + */ + if (dwc3_qcom_is_host(qcom)) pm_runtime_resume(&dwc->xhci->dev); return IRQ_HANDLED; diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c index f56c30cf151e..f6f13e7f1ba1 100644 --- a/drivers/usb/dwc3/host.c +++ b/drivers/usb/dwc3/host.c @@ -135,4 +135,5 @@ int dwc3_host_init(struct dwc3 *dwc) void dwc3_host_exit(struct dwc3 *dwc) { platform_device_unregister(dwc->xhci); + dwc->xhci = NULL; }
The Qualcomm dwc3 runtime-PM implementation checks the xhci platform-device pointer in the wakeup-interrupt handler to determine whether the controller is in host mode and if so triggers a resume. After a role switch in OTG mode the xhci platform-device would have been freed and the next wakeup from runtime suspend would access the freed memory. Note that role switching is executed from a freezable workqueue, which guarantees that the pointer is stable during suspend. Also note that runtime PM has been broken since commit 2664deb09306 ("usb: dwc3: qcom: Honor wakeup enabled/disabled state"), which incidentally also prevents this issue from being triggered. Fixes: a4333c3a6ba9 ("usb: dwc3: Add Qualcomm DWC3 glue driver") Cc: stable@vger.kernel.org # 4.18 Signed-off-by: Johan Hovold <johan+linaro@kernel.org> --- Changes in v2 - new patch drivers/usb/dwc3/dwc3-qcom.c | 14 +++++++++++++- drivers/usb/dwc3/host.c | 1 + 2 files changed, 14 insertions(+), 1 deletion(-)