linux-kernel - Re: [PATCH] usb: musb: jz4740: Prevent lockup when CONFIG

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Message-ID: <20200521212843.GD5684@iaqt7>
Date:   Thu, 21 May 2020 16:28:43 -0500
From:   Bin Liu <b-liu@...com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     <od@...c.me>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Paul Cercueil <paul@...pouillou.net>
Subject: Re: [PATCH] usb: musb: jz4740: Prevent lockup when CONFIG_SMP is set

Hi Greg,

On Wed, May 20, 2020 at 05:01:11PM +0200, Paul Cercueil wrote:
> The function dma_controller_irq() locks up the exact same spinlock we
> locked before calling it, which obviously resulted in a deadlock when
> CONFIG_SMP was enabled. This flew under the radar as none of the boards
> supported by this driver needs SMP.
> 
> Fixes: 57aadb46bd63 ("usb: musb: jz4740: Add support for DMA")
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>

Is it too late if you directly take this patch for v5.7-rc7? The bug is
introduced in v5.7-rc1. If so, here is my Acked-by:

Acked-by: Bin Liu <b-liu@...com>

Thanks,
-Bin.

> ---
>  drivers/usb/musb/jz4740.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/musb/jz4740.c b/drivers/usb/musb/jz4740.c
> index 54e7b30acc69..42c1e8bfc4be 100644
> --- a/drivers/usb/musb/jz4740.c
> +++ b/drivers/usb/musb/jz4740.c
> @@ -69,11 +69,11 @@ static irqreturn_t jz4740_musb_interrupt(int irq, void *__hci)
>  	irqreturn_t	retval = IRQ_NONE, retval_dma = IRQ_NONE;
>  	struct musb	*musb = __hci;
>  
> -	spin_lock_irqsave(&musb->lock, flags);
> -
>  	if (IS_ENABLED(CONFIG_USB_INVENTRA_DMA) && musb->dma_controller)
>  		retval_dma = dma_controller_irq(irq, musb->dma_controller);
>  
> +	spin_lock_irqsave(&musb->lock, flags);
> +
>  	musb->int_usb = musb_readb(musb->mregs, MUSB_INTRUSB);
>  	musb->int_tx = musb_readw(musb->mregs, MUSB_INTRTX);
>  	musb->int_rx = musb_readw(musb->mregs, MUSB_INTRRX);
> -- 
> 2.26.2
>