linux-kernel - Re: [PATCH 5.1 29/96] usb: gadget: udc: lpc32xx: allocate descriptor with GFP

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Date:   Wed, 10 Jul 2019 11:59:10 +0200
From:   Pavel Machek <pavel@....cz>
To:     pavel@....cz
Cc:     linux-kernel@...r.kernel.org,
        Sylvain Lemieux <slemieux.tyco@...il.com>,
        James Grant <jamesg@...tys.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.1 29/96] usb: gadget: udc: lpc32xx: allocate descriptor
 with GFP_ATOMIC

On Mon 2019-07-08 17:13:01, Greg Kroah-Hartman wrote:
> [ Upstream commit fbc318afadd6e7ae2252d6158cf7d0c5a2132f7d ]
> 
> Gadget drivers may queue request in interrupt context. This would lead to
> a descriptor allocation in that context. In that case we would hit
> BUG_ON(in_interrupt()) in __get_vm_area_node.
> 
> Also remove the unnecessary cast.

GFP_ATOMIC allocations can and do fail, but I don't see any explicit error handling.

Can someone check everything is ok?

Thanks,
									Pavel


> diff --git a/drivers/usb/gadget/udc/lpc32xx_udc.c b/drivers/usb/gadget/udc/lpc32xx_udc.c
> index b0781771704e..eafc2a00c96a 100644
> --- a/drivers/usb/gadget/udc/lpc32xx_udc.c
> +++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
> @@ -922,8 +922,7 @@ static struct lpc32xx_usbd_dd_gad *udc_dd_alloc(struct lpc32xx_udc *udc)
>  	dma_addr_t			dma;
>  	struct lpc32xx_usbd_dd_gad	*dd;
>  
> -	dd = (struct lpc32xx_usbd_dd_gad *) dma_pool_alloc(
> -			udc->dd_cache, (GFP_KERNEL | GFP_DMA), &dma);
> +	dd = dma_pool_alloc(udc->dd_cache, GFP_ATOMIC | GFP_DMA, &dma);
>  	if (dd)
>  		dd->this_dma = dma;
>  
> -- 
> 2.20.1
> 
> 

-- 
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