| Message ID | 20150312044449.GA29718@saruman.tx.rr.com (mailing list archive) |
|---|---|
| State | Rejected |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
Hi, > On Thu, Mar 12, 2015 at 04:33:41AM +0000, yoshihiro shimoda wrote: > > Hi Geert-san again, > > > > > Hi Geert-san, > > > > > > Thank you for the reply again! > > > > > > > Hi Shimoda-san, > > > > > > > > On Mon, Feb 16, 2015 at 2:52 AM, Yoshihiro Shimoda > > > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > > According to the gadget.h, a "complete" function will always be called > > > > > with interrupts disabled. However, sometimes usbhsg_queue_pop() function > > > > > is called with interrupts enabled. So, this function should calls > > > > > local_irq_save() before this calls the usb_gadget_giveback_request(). > > > > > Otherwise, there is possible to cause a spinlock suspected in a gadget > > > > > complete function. > > > > > > > > I still feel uneasy about adding the call to local_irq_save(), as the need for > > > > this is usually an indicator of another locking problem. > > > > > > I also think that I would like to avoid using local_irq_save(). > > > But, I have no idea to resolve this issue for now. > > > > After I modified usb-dmac driver to use a tasklet instead of a kthread, > > this issue disappeared. > > > > My understanding is the followings: > > - According to the backtrace below, during usbhsf_dma_complete() was running, > > a softirq happened. After ncm_tx_tasklet() was called, the issue happened. > > http://thread.gmane.org/gmane.linux.usb.general/122023/focus=43729 > > > > - This means that usbhsf_dma_complete() ran on a kthread. So, ncm driver is able > > to do the ncm_tx_tasklet(). > > > > - After the current usb-dmac driver, since usbhsf_dma_complete() runs on a tasklet, > > ncm driver is not able to do the ncm_tx_tasklet during usbhsf_dma_complete() was running. > > > > > > So, I would like to recall this patch and I will resubmit this patch series as v3. > > try something like below: > > diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c b/drivers/usb/renesas_usbhs/mod_gadget.c > index e0384af77e56..e9d75d85be59 100644 > --- a/drivers/usb/renesas_usbhs/mod_gadget.c > +++ b/drivers/usb/renesas_usbhs/mod_gadget.c > @@ -119,7 +119,7 @@ struct usbhsg_recip_handle { > /* > * queue push/pop > */ > -static void usbhsg_queue_pop(struct usbhsg_uep *uep, > +static void __usbhsg_queue_pop(struct usbhsg_uep *uep, > struct usbhsg_request *ureq, > int status) > { > @@ -133,6 +133,15 @@ static void usbhsg_queue_pop(struct usbhsg_uep *uep, > usb_gadget_giveback_request(&uep->ep, &ureq->req); > } > > +static void usbhsg_queue_pop(struct usbhsg_uep *uep, > + struct usbhsg_request *ureq, > + int status) > +{ > + usbhs_lock(priv, flags); > + __usbhsg_queue_pop(uep, ureq, status); > + usbhs_unlock(priv, flags); > +} > + > static void usbhsg_queue_done(struct usbhs_priv *priv, struct usbhs_pkt *pkt) > { > struct usbhs_pipe *pipe = pkt->pipe; > > > then, for cases where lock is already held you call __usbhsg_queue_pop() > and for all other cases, call usbhsg_queue_pop(). Thank you for the suggestion. However, we cannot use this usbhsg_queue_pop() because a gadget driver might call usb_ep_queue() in the "complete" function and this driver calls usbhs_lock() in the usb_ep_queue(). Perhaps my explanation was bad, but this issue was caused by the following conditions: - I use the renesas_usbhs driver as udc. - I use an old usb-dmac driver that the callback runs on a kthread. - I use the ncm driver. In this environment, the ncm driver might cause a spinlock suspected. As an old solution, I fixed the renesas_usbhs driver by this patch. However, if I use a new usb-dmac driver that the callback runs on a tasklet, I don't need this patch. (This is a new solution.) Best regards, Yoshihiro Shimoda -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, On Thu, Mar 12, 2015 at 05:40:56AM +0000, yoshihiro shimoda wrote: > Hi, > > > On Thu, Mar 12, 2015 at 04:33:41AM +0000, yoshihiro shimoda wrote: > > > Hi Geert-san again, > > > > > > > Hi Geert-san, > > > > > > > > Thank you for the reply again! > > > > > > > > > Hi Shimoda-san, > > > > > > > > > > On Mon, Feb 16, 2015 at 2:52 AM, Yoshihiro Shimoda > > > > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > > > According to the gadget.h, a "complete" function will always be called > > > > > > with interrupts disabled. However, sometimes usbhsg_queue_pop() function > > > > > > is called with interrupts enabled. So, this function should calls > > > > > > local_irq_save() before this calls the usb_gadget_giveback_request(). > > > > > > Otherwise, there is possible to cause a spinlock suspected in a gadget > > > > > > complete function. > > > > > > > > > > I still feel uneasy about adding the call to local_irq_save(), as the need for > > > > > this is usually an indicator of another locking problem. > > > > > > > > I also think that I would like to avoid using local_irq_save(). > > > > But, I have no idea to resolve this issue for now. > > > > > > After I modified usb-dmac driver to use a tasklet instead of a kthread, > > > this issue disappeared. > > > > > > My understanding is the followings: > > > - According to the backtrace below, during usbhsf_dma_complete() was running, > > > a softirq happened. After ncm_tx_tasklet() was called, the issue happened. > > > http://thread.gmane.org/gmane.linux.usb.general/122023/focus=43729 > > > > > > - This means that usbhsf_dma_complete() ran on a kthread. So, ncm driver is able > > > to do the ncm_tx_tasklet(). > > > > > > - After the current usb-dmac driver, since usbhsf_dma_complete() runs on a tasklet, > > > ncm driver is not able to do the ncm_tx_tasklet during usbhsf_dma_complete() was running. > > > > > > > > > So, I would like to recall this patch and I will resubmit this patch series as v3. > > > > try something like below: > > > > diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c b/drivers/usb/renesas_usbhs/mod_gadget.c > > index e0384af77e56..e9d75d85be59 100644 > > --- a/drivers/usb/renesas_usbhs/mod_gadget.c > > +++ b/drivers/usb/renesas_usbhs/mod_gadget.c > > @@ -119,7 +119,7 @@ struct usbhsg_recip_handle { > > /* > > * queue push/pop > > */ > > -static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > +static void __usbhsg_queue_pop(struct usbhsg_uep *uep, > > struct usbhsg_request *ureq, > > int status) > > { > > @@ -133,6 +133,15 @@ static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > usb_gadget_giveback_request(&uep->ep, &ureq->req); > > } > > > > +static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > + struct usbhsg_request *ureq, > > + int status) > > +{ > > + usbhs_lock(priv, flags); > > + __usbhsg_queue_pop(uep, ureq, status); > > + usbhs_unlock(priv, flags); > > +} > > + > > static void usbhsg_queue_done(struct usbhs_priv *priv, struct usbhs_pkt *pkt) > > { > > struct usbhs_pipe *pipe = pkt->pipe; > > > > > > then, for cases where lock is already held you call __usbhsg_queue_pop() > > and for all other cases, call usbhsg_queue_pop(). > > Thank you for the suggestion. However, we cannot use this > usbhsg_queue_pop() because a gadget driver might call usb_ep_queue() > in the "complete" function and this driver calls usbhs_lock() in the > usb_ep_queue(). right, in that case just call __usbhs_queue_pop() directly. > Perhaps my explanation was bad, but this issue was caused by the > following conditions: > - I use the renesas_usbhs driver as udc. > - I use an old usb-dmac driver that the callback runs on a kthread. > - I use the ncm driver. In this environment, the ncm driver might > cause a spinlock suspected. > > As an old solution, I fixed the renesas_usbhs driver by this patch. > However, if I use a new usb-dmac driver that the callback runs on a > tasklet, I don't need this patch. (This is a new solution.) then differentiate based on some revision register or something like that ?
Hi, > Hi, > > On Thu, Mar 12, 2015 at 05:40:56AM +0000, yoshihiro shimoda wrote: > > Hi, > > < snip > > > > > > > try something like below: > > > > > > diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c b/drivers/usb/renesas_usbhs/mod_gadget.c > > > index e0384af77e56..e9d75d85be59 100644 > > > --- a/drivers/usb/renesas_usbhs/mod_gadget.c > > > +++ b/drivers/usb/renesas_usbhs/mod_gadget.c > > > @@ -119,7 +119,7 @@ struct usbhsg_recip_handle { > > > /* > > > * queue push/pop > > > */ > > > -static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > > +static void __usbhsg_queue_pop(struct usbhsg_uep *uep, > > > struct usbhsg_request *ureq, > > > int status) > > > { > > > @@ -133,6 +133,15 @@ static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > > usb_gadget_giveback_request(&uep->ep, &ureq->req); > > > } > > > > > > +static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > > + struct usbhsg_request *ureq, > > > + int status) > > > +{ > > > + usbhs_lock(priv, flags); > > > + __usbhsg_queue_pop(uep, ureq, status); > > > + usbhs_unlock(priv, flags); > > > +} > > > + > > > static void usbhsg_queue_done(struct usbhs_priv *priv, struct usbhs_pkt *pkt) > > > { > > > struct usbhs_pipe *pipe = pkt->pipe; > > > > > > > > > then, for cases where lock is already held you call __usbhsg_queue_pop() > > > and for all other cases, call usbhsg_queue_pop(). > > > > Thank you for the suggestion. However, we cannot use this > > usbhsg_queue_pop() because a gadget driver might call usb_ep_queue() > > in the "complete" function and this driver calls usbhs_lock() in the > > usb_ep_queue(). > > right, in that case just call __usbhs_queue_pop() directly. Yes. So, my understanding is that this driver always calls __usbhs_queue_pop() because this driver cannot know that a gadget driver calls usb_ep_queue() or not in the "complete" function. > > Perhaps my explanation was bad, but this issue was caused by the > > following conditions: > > - I use the renesas_usbhs driver as udc. > > - I use an old usb-dmac driver that the callback runs on a kthread. > > - I use the ncm driver. In this environment, the ncm driver might > > cause a spinlock suspected. > > > > As an old solution, I fixed the renesas_usbhs driver by this patch. > > However, if I use a new usb-dmac driver that the callback runs on a > > tasklet, I don't need this patch. (This is a new solution.) > > then differentiate based on some revision register or something like > that ? Sorry for the lack information. I am submitting this usb-dmac driver that the callback runs on a tasklet now. This means that the driver is not merged yet. So, I think that we don't need to differentiate. Best regards, Yoshihiro Shimoda > -- > balbi -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, On Fri, Mar 13, 2015 at 01:14:01AM +0000, yoshihiro shimoda wrote: > > > > diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c b/drivers/usb/renesas_usbhs/mod_gadget.c > > > > index e0384af77e56..e9d75d85be59 100644 > > > > --- a/drivers/usb/renesas_usbhs/mod_gadget.c > > > > +++ b/drivers/usb/renesas_usbhs/mod_gadget.c > > > > @@ -119,7 +119,7 @@ struct usbhsg_recip_handle { > > > > /* > > > > * queue push/pop > > > > */ > > > > -static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > > > +static void __usbhsg_queue_pop(struct usbhsg_uep *uep, > > > > struct usbhsg_request *ureq, > > > > int status) > > > > { > > > > @@ -133,6 +133,15 @@ static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > > > usb_gadget_giveback_request(&uep->ep, &ureq->req); > > > > } > > > > > > > > +static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > > > + struct usbhsg_request *ureq, > > > > + int status) > > > > +{ > > > > + usbhs_lock(priv, flags); > > > > + __usbhsg_queue_pop(uep, ureq, status); > > > > + usbhs_unlock(priv, flags); > > > > +} > > > > + > > > > static void usbhsg_queue_done(struct usbhs_priv *priv, struct usbhs_pkt *pkt) > > > > { > > > > struct usbhs_pipe *pipe = pkt->pipe; > > > > > > > > > > > > then, for cases where lock is already held you call __usbhsg_queue_pop() > > > > and for all other cases, call usbhsg_queue_pop(). > > > > > > Thank you for the suggestion. However, we cannot use this > > > usbhsg_queue_pop() because a gadget driver might call usb_ep_queue() > > > in the "complete" function and this driver calls usbhs_lock() in the > > > usb_ep_queue(). > > > > right, in that case just call __usbhs_queue_pop() directly. > > Yes. So, my understanding is that this driver always calls __usbhs_queue_pop() > because this driver cannot know that a gadget driver calls usb_ep_queue() or not > in the "complete" function. but you don't need to know that. All you have to do is spin_unlock() before calling usb_gadget_giveback_request(), look at drivers/usb/dwc3/gadget.c::dwc3_gadget_giveback() > > > Perhaps my explanation was bad, but this issue was caused by the > > > following conditions: > > > - I use the renesas_usbhs driver as udc. > > > - I use an old usb-dmac driver that the callback runs on a kthread. > > > - I use the ncm driver. In this environment, the ncm driver might > > > cause a spinlock suspected. > > > > > > As an old solution, I fixed the renesas_usbhs driver by this patch. > > > However, if I use a new usb-dmac driver that the callback runs on a > > > tasklet, I don't need this patch. (This is a new solution.) > > > > then differentiate based on some revision register or something like > > that ? > > Sorry for the lack information. I am submitting this usb-dmac driver that > the callback runs on a tasklet now. This means that the driver is not > merged yet. So, I think that we don't need to differentiate. But as soon as your driver gets merged, you will need to differentiate, right ?
Hi, > Hi, > > On Fri, Mar 13, 2015 at 01:14:01AM +0000, yoshihiro shimoda wrote: > > > > > diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c b/drivers/usb/renesas_usbhs/mod_gadget.c > > > > > index e0384af77e56..e9d75d85be59 100644 > > > > > --- a/drivers/usb/renesas_usbhs/mod_gadget.c > > > > > +++ b/drivers/usb/renesas_usbhs/mod_gadget.c > > > > > @@ -119,7 +119,7 @@ struct usbhsg_recip_handle { > > > > > /* > > > > > * queue push/pop > > > > > */ > > > > > -static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > > > > +static void __usbhsg_queue_pop(struct usbhsg_uep *uep, > > > > > struct usbhsg_request *ureq, > > > > > int status) > > > > > { > > > > > @@ -133,6 +133,15 @@ static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > > > > usb_gadget_giveback_request(&uep->ep, &ureq->req); > > > > > } > > > > > > > > > > +static void usbhsg_queue_pop(struct usbhsg_uep *uep, > > > > > + struct usbhsg_request *ureq, > > > > > + int status) > > > > > +{ > > > > > + usbhs_lock(priv, flags); > > > > > + __usbhsg_queue_pop(uep, ureq, status); > > > > > + usbhs_unlock(priv, flags); > > > > > +} > > > > > + > > > > > static void usbhsg_queue_done(struct usbhs_priv *priv, struct usbhs_pkt *pkt) > > > > > { > > > > > struct usbhs_pipe *pipe = pkt->pipe; > > > > > > > > > > > > > > > then, for cases where lock is already held you call __usbhsg_queue_pop() > > > > > and for all other cases, call usbhsg_queue_pop(). > > > > > > > > Thank you for the suggestion. However, we cannot use this > > > > usbhsg_queue_pop() because a gadget driver might call usb_ep_queue() > > > > in the "complete" function and this driver calls usbhs_lock() in the > > > > usb_ep_queue(). > > > > > > right, in that case just call __usbhs_queue_pop() directly. > > > > Yes. So, my understanding is that this driver always calls __usbhs_queue_pop() > > because this driver cannot know that a gadget driver calls usb_ep_queue() or not > > in the "complete" function. > > but you don't need to know that. All you have to do is spin_unlock() > before calling usb_gadget_giveback_request(), look at > drivers/usb/dwc3/gadget.c::dwc3_gadget_giveback() Thank you for the suggestion. I understood it. > > > > Perhaps my explanation was bad, but this issue was caused by the > > > > following conditions: > > > > - I use the renesas_usbhs driver as udc. > > > > - I use an old usb-dmac driver that the callback runs on a kthread. > > > > - I use the ncm driver. In this environment, the ncm driver might > > > > cause a spinlock suspected. > > > > > > > > As an old solution, I fixed the renesas_usbhs driver by this patch. > > > > However, if I use a new usb-dmac driver that the callback runs on a > > > > tasklet, I don't need this patch. (This is a new solution.) > > > > > > then differentiate based on some revision register or something like > > > that ? > > > > Sorry for the lack information. I am submitting this usb-dmac driver that > > the callback runs on a tasklet now. This means that the driver is not > > merged yet. So, I think that we don't need to differentiate. > > But as soon as your driver gets merged, you will need to differentiate, > right ? Right. So, I will submit v3 patch soon. Best regards, Yoshihiro Shimoda > -- > balbi -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c b/drivers/usb/renesas_usbhs/mod_gadget.c index e0384af77e56..e9d75d85be59 100644 --- a/drivers/usb/renesas_usbhs/mod_gadget.c +++ b/drivers/usb/renesas_usbhs/mod_gadget.c @@ -119,7 +119,7 @@ struct usbhsg_recip_handle { /* * queue push/pop */ -static void usbhsg_queue_pop(struct usbhsg_uep *uep, +static void __usbhsg_queue_pop(struct usbhsg_uep *uep, struct usbhsg_request *ureq, int status) { @@ -133,6 +133,15 @@ static void usbhsg_queue_pop(struct usbhsg_uep *uep, usb_gadget_giveback_request(&uep->ep, &ureq->req); } +static void usbhsg_queue_pop(struct usbhsg_uep *uep, + struct usbhsg_request *ureq, + int status) +{ + usbhs_lock(priv, flags); + __usbhsg_queue_pop(uep, ureq, status); + usbhs_unlock(priv, flags); +} + static void usbhsg_queue_done(struct usbhs_priv *priv, struct usbhs_pkt *pkt) { struct usbhs_pipe *pipe = pkt->pipe;