| Message ID | 20160707222114.1673-9-stephen.boyd@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jul 07, 2016 at 03:20:59PM -0700, Stephen Boyd wrote: > We don't call hw_device_reset() with the ci->lock held, so it > doesn't seem like this lock here is protecting anything. Let's > just remove it. This allows us to call sleeping functions like > phy_init() from within the CI_HDRC_CONTROLLER_RESET_EVENT hook. > > Cc: Peter Chen <peter.chen@nxp.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org> > --- > drivers/usb/chipidea/udc.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c > index 065f5d97aa67..f16be4710cdb 100644 > --- a/drivers/usb/chipidea/udc.c > +++ b/drivers/usb/chipidea/udc.c > @@ -1719,7 +1719,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > struct usb_gadget_driver *driver) > { > struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget); > - unsigned long flags; > int retval = -ENOMEM; > > if (driver->disconnect == NULL) > @@ -1746,7 +1745,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > pm_runtime_get_sync(&ci->gadget.dev); > if (ci->vbus_active) { > - spin_lock_irqsave(&ci->lock, flags); > hw_device_reset(ci); > } else { > usb_udc_vbus_handler(&ci->gadget, false); > @@ -1755,7 +1753,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > } > > retval = hw_device_state(ci, ci->ep0out->qh.dma); > - spin_unlock_irqrestore(&ci->lock, flags); > if (retval) > pm_runtime_put_sync(&ci->gadget.dev); > The main purpose for this is disabling interrupt when reset controller, in case the unexpected interrupts occur. You can move this between hw_device_state.
Quoting Peter Chen (2016-07-08 02:45:28) > On Thu, Jul 07, 2016 at 03:20:59PM -0700, Stephen Boyd wrote: > > We don't call hw_device_reset() with the ci->lock held, so it > > doesn't seem like this lock here is protecting anything. Let's > > just remove it. This allows us to call sleeping functions like > > phy_init() from within the CI_HDRC_CONTROLLER_RESET_EVENT hook. > > > > Cc: Peter Chen <peter.chen@nxp.com> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org> > > --- > > drivers/usb/chipidea/udc.c | 3 --- > > 1 file changed, 3 deletions(-) > > > > diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c > > index 065f5d97aa67..f16be4710cdb 100644 > > --- a/drivers/usb/chipidea/udc.c > > +++ b/drivers/usb/chipidea/udc.c > > @@ -1719,7 +1719,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > struct usb_gadget_driver *driver) > > { > > struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget); > > - unsigned long flags; > > int retval = -ENOMEM; > > > > if (driver->disconnect == NULL) > > @@ -1746,7 +1745,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > > > pm_runtime_get_sync(&ci->gadget.dev); > > if (ci->vbus_active) { > > - spin_lock_irqsave(&ci->lock, flags); > > hw_device_reset(ci); > > } else { > > usb_udc_vbus_handler(&ci->gadget, false); > > @@ -1755,7 +1753,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > } > > > > retval = hw_device_state(ci, ci->ep0out->qh.dma); > > - spin_unlock_irqrestore(&ci->lock, flags); > > if (retval) > > pm_runtime_put_sync(&ci->gadget.dev); > > > > The main purpose for this is disabling interrupt when reset controller, > in case the unexpected interrupts occur. > > You can move this between hw_device_state. > Ok, but we don't hold the ci->lock in ci_udc_vbus_session(). Is that a bug as well?
On Fri, Aug 05, 2016 at 02:53:56PM -0700, Stephen Boyd wrote: > Quoting Peter Chen (2016-07-08 02:45:28) > > On Thu, Jul 07, 2016 at 03:20:59PM -0700, Stephen Boyd wrote: > > > We don't call hw_device_reset() with the ci->lock held, so it > > > doesn't seem like this lock here is protecting anything. Let's > > > just remove it. This allows us to call sleeping functions like > > > phy_init() from within the CI_HDRC_CONTROLLER_RESET_EVENT hook. > > > > > > Cc: Peter Chen <peter.chen@nxp.com> > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org> > > > --- > > > drivers/usb/chipidea/udc.c | 3 --- > > > 1 file changed, 3 deletions(-) > > > > > > diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c > > > index 065f5d97aa67..f16be4710cdb 100644 > > > --- a/drivers/usb/chipidea/udc.c > > > +++ b/drivers/usb/chipidea/udc.c > > > @@ -1719,7 +1719,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > > struct usb_gadget_driver *driver) > > > { > > > struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget); > > > - unsigned long flags; > > > int retval = -ENOMEM; > > > > > > if (driver->disconnect == NULL) > > > @@ -1746,7 +1745,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > > > > > pm_runtime_get_sync(&ci->gadget.dev); > > > if (ci->vbus_active) { > > > - spin_lock_irqsave(&ci->lock, flags); > > > hw_device_reset(ci); > > > } else { > > > usb_udc_vbus_handler(&ci->gadget, false); > > > @@ -1755,7 +1753,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > > } > > > > > > retval = hw_device_state(ci, ci->ep0out->qh.dma); > > > - spin_unlock_irqrestore(&ci->lock, flags); > > > if (retval) > > > pm_runtime_put_sync(&ci->gadget.dev); > > > > > > > The main purpose for this is disabling interrupt when reset controller, > > in case the unexpected interrupts occur. > > > > You can move this between hw_device_state. > > > > Ok, but we don't hold the ci->lock in ci_udc_vbus_session(). Is that a > bug as well? I agree with your patch. In fact, during the reset controller, the interrupt has not been enabled, it should no unexpected interrupt.
Quoting Peter Chen (2016-08-06 00:54:35) > On Fri, Aug 05, 2016 at 02:53:56PM -0700, Stephen Boyd wrote: > > Quoting Peter Chen (2016-07-08 02:45:28) > > > On Thu, Jul 07, 2016 at 03:20:59PM -0700, Stephen Boyd wrote: > > > > We don't call hw_device_reset() with the ci->lock held, so it > > > > doesn't seem like this lock here is protecting anything. Let's > > > > just remove it. This allows us to call sleeping functions like > > > > phy_init() from within the CI_HDRC_CONTROLLER_RESET_EVENT hook. > > > > > > > > Cc: Peter Chen <peter.chen@nxp.com> > > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > > Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org> > > > > --- > > > > drivers/usb/chipidea/udc.c | 3 --- > > > > 1 file changed, 3 deletions(-) > > > > > > > > diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c > > > > index 065f5d97aa67..f16be4710cdb 100644 > > > > --- a/drivers/usb/chipidea/udc.c > > > > +++ b/drivers/usb/chipidea/udc.c > > > > @@ -1719,7 +1719,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > > > struct usb_gadget_driver *driver) > > > > { > > > > struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget); > > > > - unsigned long flags; > > > > int retval = -ENOMEM; > > > > > > > > if (driver->disconnect == NULL) > > > > @@ -1746,7 +1745,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > > > > > > > pm_runtime_get_sync(&ci->gadget.dev); > > > > if (ci->vbus_active) { > > > > - spin_lock_irqsave(&ci->lock, flags); > > > > hw_device_reset(ci); > > > > } else { > > > > usb_udc_vbus_handler(&ci->gadget, false); > > > > @@ -1755,7 +1753,6 @@ static int ci_udc_start(struct usb_gadget *gadget, > > > > } > > > > > > > > retval = hw_device_state(ci, ci->ep0out->qh.dma); > > > > - spin_unlock_irqrestore(&ci->lock, flags); > > > > if (retval) > > > > pm_runtime_put_sync(&ci->gadget.dev); > > > > > > > > > > The main purpose for this is disabling interrupt when reset controller, > > > in case the unexpected interrupts occur. > > > > > > You can move this between hw_device_state. > > > > > > > Ok, but we don't hold the ci->lock in ci_udc_vbus_session(). Is that a > > bug as well? > > I agree with your patch. In fact, during the reset controller, the > interrupt has not been enabled, it should no unexpected interrupt. > So then we can leave this patch as is? It still isn't clear to me what sequence of events that would cause a problem if we don't hold the ci->lock around hw_device_state().
>Quoting Peter Chen (2016-08-06 00:54:35) >> On Fri, Aug 05, 2016 at 02:53:56PM -0700, Stephen Boyd wrote: >> > Quoting Peter Chen (2016-07-08 02:45:28) >> > > On Thu, Jul 07, 2016 at 03:20:59PM -0700, Stephen Boyd wrote: >> > > > We don't call hw_device_reset() with the ci->lock held, so it >> > > > doesn't seem like this lock here is protecting anything. Let's >> > > > just remove it. This allows us to call sleeping functions like >> > > > phy_init() from within the CI_HDRC_CONTROLLER_RESET_EVENT hook. >> > > > >> > > > Cc: Peter Chen <peter.chen@nxp.com> >> > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >> > > > Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org> >> > > > --- >> > > > drivers/usb/chipidea/udc.c | 3 --- >> > > > 1 file changed, 3 deletions(-) >> > > > >> > > > diff --git a/drivers/usb/chipidea/udc.c >> > > > b/drivers/usb/chipidea/udc.c index 065f5d97aa67..f16be4710cdb >> > > > 100644 >> > > > --- a/drivers/usb/chipidea/udc.c >> > > > +++ b/drivers/usb/chipidea/udc.c >> > > > @@ -1719,7 +1719,6 @@ static int ci_udc_start(struct usb_gadget *gadget, >> > > > struct usb_gadget_driver *driver) { >> > > > struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget); >> > > > - unsigned long flags; >> > > > int retval = -ENOMEM; >> > > > >> > > > if (driver->disconnect == NULL) @@ -1746,7 +1745,6 @@ >> > > > static int ci_udc_start(struct usb_gadget *gadget, >> > > > >> > > > pm_runtime_get_sync(&ci->gadget.dev); >> > > > if (ci->vbus_active) { >> > > > - spin_lock_irqsave(&ci->lock, flags); >> > > > hw_device_reset(ci); >> > > > } else { >> > > > usb_udc_vbus_handler(&ci->gadget, false); @@ >> > > > -1755,7 +1753,6 @@ static int ci_udc_start(struct usb_gadget *gadget, >> > > > } >> > > > >> > > > retval = hw_device_state(ci, ci->ep0out->qh.dma); >> > > > - spin_unlock_irqrestore(&ci->lock, flags); >> > > > if (retval) >> > > > pm_runtime_put_sync(&ci->gadget.dev); >> > > > >> > > >> > > The main purpose for this is disabling interrupt when reset >> > > controller, in case the unexpected interrupts occur. >> > > >> > > You can move this between hw_device_state. >> > > >> > >> > Ok, but we don't hold the ci->lock in ci_udc_vbus_session(). Is that >> > a bug as well? >> >> I agree with your patch. In fact, during the reset controller, the >> interrupt has not been enabled, it should no unexpected interrupt. >> > >So then we can leave this patch as is? It still isn't clear to me what sequence of >events that would cause a problem if we don't hold the >ci->lock around hw_device_state(). Yes. I am ok with this patch. After thinking more, it is safe to be without lock. And we have this unlock code in nxp internal tree, and without any problems during 1-2 years. Acked-by: Peter Chen <peter.chen@nxp.com> Peter
diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c index 065f5d97aa67..f16be4710cdb 100644 --- a/drivers/usb/chipidea/udc.c +++ b/drivers/usb/chipidea/udc.c @@ -1719,7 +1719,6 @@ static int ci_udc_start(struct usb_gadget *gadget, struct usb_gadget_driver *driver) { struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget); - unsigned long flags; int retval = -ENOMEM; if (driver->disconnect == NULL) @@ -1746,7 +1745,6 @@ static int ci_udc_start(struct usb_gadget *gadget, pm_runtime_get_sync(&ci->gadget.dev); if (ci->vbus_active) { - spin_lock_irqsave(&ci->lock, flags); hw_device_reset(ci); } else { usb_udc_vbus_handler(&ci->gadget, false); @@ -1755,7 +1753,6 @@ static int ci_udc_start(struct usb_gadget *gadget, } retval = hw_device_state(ci, ci->ep0out->qh.dma); - spin_unlock_irqrestore(&ci->lock, flags); if (retval) pm_runtime_put_sync(&ci->gadget.dev);
We don't call hw_device_reset() with the ci->lock held, so it doesn't seem like this lock here is protecting anything. Let's just remove it. This allows us to call sleeping functions like phy_init() from within the CI_HDRC_CONTROLLER_RESET_EVENT hook. Cc: Peter Chen <peter.chen@nxp.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org> --- drivers/usb/chipidea/udc.c | 3 --- 1 file changed, 3 deletions(-)