Commit 51fe9cd2 authored by Sascha Hauer's avatar Sascha Hauer Committed by Vinod Koul
Browse files

dmaengine: virt-dma: Add missing locking 



Originally freeing descriptors was split into a locked and an unlocked
part. The locked part in vchan_get_all_descriptors() collected all
descriptors on a separate list_head. This was done to allow iterating
over that new list in vchan_dma_desc_free_list() without a lock held.

This became broken in 13bb26ae ("dmaengine: virt-dma: don't always
free descriptor upon completion"). With this commit
vchan_dma_desc_free_list() no longer exclusively operates on the
separate list, but starts to put descriptors which can be reused back on
&vc->desc_allocated. This list operation should have been locked, but
wasn't.
In the mean time drivers started to call vchan_dma_desc_free_list() with
their lock held so that we now have the situation that
vchan_dma_desc_free_list() is called locked from some drivers and
unlocked from others.
To clean this up we have to do two things:

1. Add missing locking in vchan_dma_desc_free_list()
2. Make sure drivers call vchan_dma_desc_free_list() unlocked

This needs to be done atomically, so in this patch the locking is added
and all drivers are fixed.

Signed-off-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: default avatarPeter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: default avatarPeter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: default avatarGreen Wan <green.wan@sifive.com>
Tested-by: default avatarGreen Wan <green.wan@sifive.com>
Link: https://lore.kernel.org/r/20191216105328.15198-3-s.hauer@pengutronix.de


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent 5c8aacbb

drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c

+2 −6
Original line number Diff line number Diff line
@@ -636,14 +636,10 @@ static int dma_chan_terminate_all(struct dma_chan *dchan) 


	vchan_get_all_descriptors(&chan->vc, &head);



	/*

	 * As vchan_dma_desc_free_list can access to desc_allocated list

	 * we need to call it in vc.lock context.

	 */

	vchan_dma_desc_free_list(&chan->vc, &head);



	spin_unlock_irqrestore(&chan->vc.lock, flags);



	vchan_dma_desc_free_list(&chan->vc, &head);



	dev_vdbg(dchan2dev(dchan), "terminated: %s\n", axi_chan_name(chan));



	return 0;

drivers/dma/mediatek/mtk-uart-apdma.c

+2 −1
Original line number Diff line number Diff line
@@ -430,9 +430,10 @@ static int mtk_uart_apdma_terminate_all(struct dma_chan *chan) 


	spin_lock_irqsave(&c->vc.lock, flags);

	vchan_get_all_descriptors(&c->vc, &head);

	vchan_dma_desc_free_list(&c->vc, &head);

	spin_unlock_irqrestore(&c->vc.lock, flags);



	vchan_dma_desc_free_list(&c->vc, &head);



	return 0;

}

drivers/dma/owl-dma.c

+2 −1
Original line number Diff line number Diff line
@@ -674,10 +674,11 @@ static int owl_dma_terminate_all(struct dma_chan *chan) 
	}



	vchan_get_all_descriptors(&vchan->vc, &head);

	vchan_dma_desc_free_list(&vchan->vc, &head);



	spin_unlock_irqrestore(&vchan->vc.lock, flags);



	vchan_dma_desc_free_list(&vchan->vc, &head);



	return 0;

}

drivers/dma/s3c24xx-dma.c

+11 −11
Original line number Diff line number Diff line
@@ -519,15 +519,6 @@ static void s3c24xx_dma_start_next_txd(struct s3c24xx_dma_chan *s3cchan) 
	s3c24xx_dma_start_next_sg(s3cchan, txd);

}



static void s3c24xx_dma_free_txd_list(struct s3c24xx_dma_engine *s3cdma,

				struct s3c24xx_dma_chan *s3cchan)

{

	LIST_HEAD(head);



	vchan_get_all_descriptors(&s3cchan->vc, &head);

	vchan_dma_desc_free_list(&s3cchan->vc, &head);

}



/*

 * Try to allocate a physical channel.  When successful, assign it to

 * this virtual channel, and initiate the next descriptor.  The
@@ -709,8 +700,9 @@ static int s3c24xx_dma_terminate_all(struct dma_chan *chan) 
{

	struct s3c24xx_dma_chan *s3cchan = to_s3c24xx_dma_chan(chan);

	struct s3c24xx_dma_engine *s3cdma = s3cchan->host;

	LIST_HEAD(head);

	unsigned long flags;

	int ret = 0;

	int ret;



	spin_lock_irqsave(&s3cchan->vc.lock, flags);
@@ -734,7 +726,15 @@ static int s3c24xx_dma_terminate_all(struct dma_chan *chan) 
	}



	/* Dequeue jobs not yet fired as well */

	s3c24xx_dma_free_txd_list(s3cdma, s3cchan);



	vchan_get_all_descriptors(&s3cchan->vc, &head);



	spin_unlock_irqrestore(&s3cchan->vc.lock, flags);



	vchan_dma_desc_free_list(&s3cchan->vc, &head);



	return 0;



unlock:

	spin_unlock_irqrestore(&s3cchan->vc.lock, flags);

drivers/dma/sf-pdma/sf-pdma.c

+2 −2
Original line number Diff line number Diff line
@@ -155,9 +155,9 @@ static void sf_pdma_free_chan_resources(struct dma_chan *dchan) 
	kfree(chan->desc);

	chan->desc = NULL;

	vchan_get_all_descriptors(&chan->vchan, &head);

	vchan_dma_desc_free_list(&chan->vchan, &head);

	sf_pdma_disclaim_chan(chan);

	spin_unlock_irqrestore(&chan->vchan.lock, flags);

	vchan_dma_desc_free_list(&chan->vchan, &head);

}



static size_t sf_pdma_desc_residue(struct sf_pdma_chan *chan,
@@ -220,8 +220,8 @@ static int sf_pdma_terminate_all(struct dma_chan *dchan) 
	chan->desc = NULL;

	chan->xfer_err = false;

	vchan_get_all_descriptors(&chan->vchan, &head);

	vchan_dma_desc_free_list(&chan->vchan, &head);

	spin_unlock_irqrestore(&chan->vchan.lock, flags);

	vchan_dma_desc_free_list(&chan->vchan, &head);



	return 0;

}

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