Re: [PATCH 3.16 167/217] usb: renesas_usbhs: fix to avoid using a disabled ep in usbhsg_queue_done()

[Ben Hutchings]

On Wed, 2016-04-27 at 01:02 +0200, Ben Hutchings wrote:
> 3.16.35-rc1 review patch.ÂÂIf anyone has any objections, please let me know.

Also dropping this from 3.16-longterm.

Ben.

> ------------------
> 
> From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> 
> commit 4fccb0767fdbdb781a9c5b5c15ee7b219443c89d upstream.
> 
> This patch fixes an issue that usbhsg_queue_done() may cause kernel
> panic when dma callback is running and usb_ep_disable() is called
> by interrupt handler. (Especially, we can reproduce this issue using
> g_audio with usb-dmac driver.)
> 
> For example of a flow:
> Âusbhsf_dma_complete (on tasklet)
> Â --> usbhsf_pkt_handler (on tasklet)
> ÂÂÂ--> usbhsg_queue_done (on tasklet)
> ÂÂÂÂ*** interrupt happened and usb_ep_disable() is called ***
> ÂÂÂÂ--> usbhsg_queue_pop (on tasklet)
> ÂÂÂÂÂThen, oops happened.
> 
> Fixes: e73a989 ("usb: renesas_usbhs: add DMAEngine support")
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
> ---
> Âdrivers/usb/renesas_usbhs/mod_gadget.c | 6 +++++-
> Â1 file changed, 5 insertions(+), 1 deletion(-)
> 
> --- a/drivers/usb/renesas_usbhs/mod_gadget.c
> +++ b/drivers/usb/renesas_usbhs/mod_gadget.c
> @@ -137,10 +137,14 @@ static void usbhsg_queue_done(struct usb
> Â	struct usbhs_pipe *pipe = pkt->pipe;
> Â	struct usbhsg_uep *uep = usbhsg_pipe_to_uep(pipe);
> Â	struct usbhsg_request *ureq = usbhsg_pkt_to_ureq(pkt);
> +	unsigned long flags;
> Â
> Â	ureq->req.actual = pkt->actual;
> Â
> -	usbhsg_queue_pop(uep, ureq, 0);
> +	usbhs_lock(priv, flags);
> +	if (uep)
> +		__usbhsg_queue_pop(uep, ureq, 0);
> +	usbhs_unlock(priv, flags);
> Â}
> Â
> Âstatic void usbhsg_queue_push(struct usbhsg_uep *uep,
> 
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-- 
Ben Hutchings
All extremists should be taken out and shot.

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