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@xxxxxxxxxxx> 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(). -- balbi
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