Re: [RESEND PATCH] dmaengine: ptdma: check for null desc before calling pt_cmd_callback

[Vinod Koul <vkoul@kernel.org>]

On 09-02-23, 21:37, Eric Pilmore wrote:
> From: Eric Pilmore <epilmore@gigaio.com>
> 
> Resolves a panic that can occur on AMD systems, typically during host
> shutdown, after the PTDMA driver had been exercised. The issue was
> the pt_issue_pending() function is mistakenly assuming that there will
> be at least one descriptor in the Submitted queue when the function
> is called. However, it is possible that both the Submitted and Issued
> queues could be empty, which could result in pt_cmd_callback() being
> mistakenly called with a NULL pointer.
> Ref: Bugzilla Bug 216856.
> 
> Fixes: 6fa7e0e836e2 ("dmaengine: ptdma: fix concurrency issue with
> multiple dma transfer")

This should not be split two two lines!

> Signed-off-by: Eric Pilmore <epilmore@gigaio.com>
> ---
>  drivers/dma/ptdma/ptdma-dmaengine.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/ptdma/ptdma-dmaengine.c
> b/drivers/dma/ptdma/ptdma-dmaengine.c
> index cc22d162ce25..1aa65e5de0f3 100644
> --- a/drivers/dma/ptdma/ptdma-dmaengine.c
> +++ b/drivers/dma/ptdma/ptdma-dmaengine.c
> @@ -254,7 +254,7 @@ static void pt_issue_pending(struct dma_chan *dma_chan)
>         spin_unlock_irqrestore(&chan->vc.lock, flags);
> 
>         /* If there was nothing active, start processing */
> -       if (engine_is_idle)
> +       if (engine_is_idle && desc)

Please run checkpatch before sending patches

WARNING: please, no spaces at the start of a line
#40: FILE: drivers/dma/ptdma/ptdma-dmaengine.c:257:
+       if (engine_is_idle && desc)$

WARNING: suspect code indent for conditional statements (7, 15)
#40: FILE: drivers/dma/ptdma/ptdma-dmaengine.c:257:
+       if (engine_is_idle && desc)
                pt_cmd_callback(desc, 0);

>                 pt_cmd_callback(desc, 0);
>  }
> 
> --
> 2.38.1

-- 
~Vinod