dmaengine Archive on lore.kernel.org
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From: Lucas Stach <l.stach@pengutronix.de>
To: Philipp Puschmann <philipp.puschmann@emlix.com>,
	linux-kernel@vger.kernel.org
Cc: jlu@pengutronix.de, yibin.gong@nxp.com, fugang.duan@nxp.com,
	dan.j.williams@intel.com, vkoul@kernel.org, shawnguo@kernel.org,
	s.hauer@pengutronix.de, kernel@pengutronix.de,
	festevam@gmail.com, linux-imx@nxp.com, dmaengine@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 1/3] dmaengine: imx-sdma: fix buffer ownership
Date: Tue, 03 Dec 2019 10:47:48 +0100
Message-ID: <9e210702979c45c11d16bf5df97b75863da587d0.camel@pengutronix.de> (raw)
In-Reply-To: <20190923135808.815-2-philipp.puschmann@emlix.com>

On Mo, 2019-09-23 at 15:58 +0200, Philipp Puschmann wrote:
> BD_DONE flag marks ownership of the buffer. When 1 SDMA owns the
> buffer, when 0 ARM owns it. When processing the buffers in
> sdma_update_channel_loop the ownership of the currently processed
> buffer was set to SDMA again before running the callback function of
> the buffer and while the sdma script may be running in parallel. So
> there was the possibility to get the buffer overwritten by SDMA
> before
> it has been processed by kernel leading to kind of random errors in
> the
> upper layers, e.g. bluetooth.
> 
> Fixes: 1ec1e82f2510 ("dmaengine: Add Freescale i.MX SDMA support")
> Signed-off-by: Philipp Puschmann <philipp.puschmann@emlix.com>

Reviewed-by: Lucas Stach <l.stach@pengutronix.de>

> ---
> 
> Changelog v5:
>  - no changes
> 
> Changelog v4:
>  - fixed the fixes tag
>  
> Changelog v3:
>  - use correct dma_wmb() instead of dma_wb()
>  - add fixes tag
> 
> Changelog v2:
>  - add dma_wb()
>  
>  drivers/dma/imx-sdma.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index 9ba74ab7e912..b42281604e54 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -802,7 +802,6 @@ static void sdma_update_channel_loop(struct
> sdma_channel *sdmac)
>  		*/
>  
>  		desc->chn_real_count = bd->mode.count;
> -		bd->mode.status |= BD_DONE;
>  		bd->mode.count = desc->period_len;
>  		desc->buf_ptail = desc->buf_tail;
>  		desc->buf_tail = (desc->buf_tail + 1) % desc->num_bd;
> @@ -817,6 +816,9 @@ static void sdma_update_channel_loop(struct
> sdma_channel *sdmac)
>  		dmaengine_desc_get_callback_invoke(&desc->vd.tx, NULL);
>  		spin_lock(&sdmac->vc.lock);
>  
> +		dma_wmb();
> +		bd->mode.status |= BD_DONE;
> +
>  		if (error)
>  			sdmac->status = old_status;
>  	}


  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-23 13:58 [PATCH v5 0/3] Fix UART DMA freezes for i.MX SOCs Philipp Puschmann
2019-09-23 13:58 ` [PATCH v5 1/3] dmaengine: imx-sdma: fix buffer ownership Philipp Puschmann
2019-12-03  9:47   ` Lucas Stach [this message]
2019-12-04  9:19   ` Robin Gong
2019-12-10  9:44     ` Philipp Puschmann
2019-12-10 13:01       ` Robin Gong
2019-09-23 13:58 ` [PATCH v5 2/3] dmaengine: imx-sdma: fix dma freezes Philipp Puschmann
2019-09-24  3:14   ` Robin Gong
2019-09-23 13:58 ` [PATCH v5 3/3] dmaengine: imx-sdma: drop redundant variable Philipp Puschmann
2019-09-23 14:55 ` [PATCH v5 0/3] Fix UART DMA freezes for i.MX SOCs Adam Ford
2019-09-23 15:06   ` Philipp Puschmann
2019-09-23 15:09     ` Jan Lübbe

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