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Commit a2769913 authored by Ilya Yanok's avatar Ilya Yanok Committed by Grant Likely
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powerpc/512x: try to free dma descriptors in case of allocation failure 



Currently completed descriptors are processed in the tasklet. This can
lead to dead lock in case of CONFIG_NET_DMA enabled (new requests are
submitted from softirq context and dma_memcpy_to_iovec() busy loops until
the requests is submitted). To prevent this we should process completed
descriptors from the allocation failure path in prepare_memcpy too.

Signed-off-by: default avatarIlya Yanok <yanok@emcraft.com>
Cc: Piotr Ziecik <kosmo@semihalf.com>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent ba2eea25

drivers/dma/mpc512x_dma.c

+45 −34
Original line number Diff line number Diff line
@@ -328,19 +328,55 @@ static irqreturn_t mpc_dma_irq(int irq, void *data) 
	return IRQ_HANDLED;

}



/* DMA Tasklet */

static void mpc_dma_tasklet(unsigned long data)

/* proccess completed descriptors */

static void mpc_dma_process_completed(struct mpc_dma *mdma)

{

	struct mpc_dma *mdma = (void *)data;

	dma_cookie_t last_cookie = 0;

	struct mpc_dma_chan *mchan;

	struct mpc_dma_desc *mdesc;

	struct dma_async_tx_descriptor *desc;

	unsigned long flags;

	LIST_HEAD(list);

	uint es;

	int i;



	for (i = 0; i < mdma->dma.chancnt; i++) {

		mchan = &mdma->channels[i];



		/* Get all completed descriptors */

		spin_lock_irqsave(&mchan->lock, flags);

		if (!list_empty(&mchan->completed))

			list_splice_tail_init(&mchan->completed, &list);

		spin_unlock_irqrestore(&mchan->lock, flags);



		if (list_empty(&list))

			continue;



		/* Execute callbacks and run dependencies */

		list_for_each_entry(mdesc, &list, node) {

			desc = &mdesc->desc;



			if (desc->callback)

				desc->callback(desc->callback_param);



			last_cookie = desc->cookie;

			dma_run_dependencies(desc);

		}



		/* Free descriptors */

		spin_lock_irqsave(&mchan->lock, flags);

		list_splice_tail_init(&list, &mchan->free);

		mchan->completed_cookie = last_cookie;

		spin_unlock_irqrestore(&mchan->lock, flags);

	}

}



/* DMA Tasklet */

static void mpc_dma_tasklet(unsigned long data)

{

	struct mpc_dma *mdma = (void *)data;

	unsigned long flags;

	uint es;



	spin_lock_irqsave(&mdma->error_status_lock, flags);

	es = mdma->error_status;

	mdma->error_status = 0;
@@ -379,35 +415,7 @@ static void mpc_dma_tasklet(unsigned long data) 
			dev_err(mdma->dma.dev, "- Destination Bus Error\n");

	}



	for (i = 0; i < mdma->dma.chancnt; i++) {

		mchan = &mdma->channels[i];



		/* Get all completed descriptors */

		spin_lock_irqsave(&mchan->lock, flags);

		if (!list_empty(&mchan->completed))

			list_splice_tail_init(&mchan->completed, &list);

		spin_unlock_irqrestore(&mchan->lock, flags);



		if (list_empty(&list))

			continue;



		/* Execute callbacks and run dependencies */

		list_for_each_entry(mdesc, &list, node) {

			desc = &mdesc->desc;



			if (desc->callback)

				desc->callback(desc->callback_param);



			last_cookie = desc->cookie;

			dma_run_dependencies(desc);

		}



		/* Free descriptors */

		spin_lock_irqsave(&mchan->lock, flags);

		list_splice_tail_init(&list, &mchan->free);

		mchan->completed_cookie = last_cookie;

		spin_unlock_irqrestore(&mchan->lock, flags);

	}

	mpc_dma_process_completed(mdma);

}



/* Submit descriptor to hardware */
@@ -587,8 +595,11 @@ mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src, 
	}

	spin_unlock_irqrestore(&mchan->lock, iflags);



	if (!mdesc)

	if (!mdesc) {

		/* try to free completed descriptors */

		mpc_dma_process_completed(mdma);

		return NULL;

	}



	mdesc->error = 0;

	tcd = mdesc->tcd;