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: Ilya Yanok <yanok@emcraft.com> Cc: Piotr Ziecik <kosmo@semihalf.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

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: Ilya Yanok <yanok@emcraft.com> Cc: Piotr Ziecik <kosmo@semihalf.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Ilya Yanok · Grant Likely
1 parent ba2eea251f
Showing 1 changed file with 45 additions and 34 deletions Side-by-side Diff
drivers/dma/mpc512x_dma.c
@@ -328,19 +328,55 @@
 	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 @@
 			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 @@
 	}
 	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;
...	...	@@ -328,19 +328,55 @@
328	328	return IRQ_HANDLED;
329	329	}
330	330
331		-/* DMA Tasklet */
332		-static void mpc_dma_tasklet(unsigned long data)
	331	+/* proccess completed descriptors */
	332	+static void mpc_dma_process_completed(struct mpc_dma *mdma)
333	333	{
334		- struct mpc_dma mdma = (void )data;
335	334	dma_cookie_t last_cookie = 0;
336	335	struct mpc_dma_chan *mchan;
337	336	struct mpc_dma_desc *mdesc;
338	337	struct dma_async_tx_descriptor *desc;
339	338	unsigned long flags;
340	339	LIST_HEAD(list);
341		- uint es;
342	340	int i;
343	341
	342	+ for (i = 0; i < mdma->dma.chancnt; i++) {
	343	+ mchan = &mdma->channels[i];
	344	+
	345	+ /* Get all completed descriptors */
	346	+ spin_lock_irqsave(&mchan->lock, flags);
	347	+ if (!list_empty(&mchan->completed))
	348	+ list_splice_tail_init(&mchan->completed, &list);
	349	+ spin_unlock_irqrestore(&mchan->lock, flags);
	350	+
	351	+ if (list_empty(&list))
	352	+ continue;
	353	+
	354	+ /* Execute callbacks and run dependencies */
	355	+ list_for_each_entry(mdesc, &list, node) {
	356	+ desc = &mdesc->desc;
	357	+
	358	+ if (desc->callback)
	359	+ desc->callback(desc->callback_param);
	360	+
	361	+ last_cookie = desc->cookie;
	362	+ dma_run_dependencies(desc);
	363	+ }
	364	+
	365	+ /* Free descriptors */
	366	+ spin_lock_irqsave(&mchan->lock, flags);
	367	+ list_splice_tail_init(&list, &mchan->free);
	368	+ mchan->completed_cookie = last_cookie;
	369	+ spin_unlock_irqrestore(&mchan->lock, flags);
	370	+ }
	371	+}
	372	+
	373	+/* DMA Tasklet */
	374	+static void mpc_dma_tasklet(unsigned long data)
	375	+{
	376	+ struct mpc_dma mdma = (void )data;
	377	+ unsigned long flags;
	378	+ uint es;
	379	+
344	380	spin_lock_irqsave(&mdma->error_status_lock, flags);
345	381	es = mdma->error_status;
346	382	mdma->error_status = 0;
...	...	@@ -379,35 +415,7 @@
379	415	dev_err(mdma->dma.dev, "- Destination Bus Error\n");
380	416	}
381	417
382		- for (i = 0; i < mdma->dma.chancnt; i++) {
383		- mchan = &mdma->channels[i];
384		-
385		- /* Get all completed descriptors */
386		- spin_lock_irqsave(&mchan->lock, flags);
387		- if (!list_empty(&mchan->completed))
388		- list_splice_tail_init(&mchan->completed, &list);
389		- spin_unlock_irqrestore(&mchan->lock, flags);
390		-
391		- if (list_empty(&list))
392		- continue;
393		-
394		- /* Execute callbacks and run dependencies */
395		- list_for_each_entry(mdesc, &list, node) {
396		- desc = &mdesc->desc;
397		-
398		- if (desc->callback)
399		- desc->callback(desc->callback_param);
400		-
401		- last_cookie = desc->cookie;
402		- dma_run_dependencies(desc);
403		- }
404		-
405		- /* Free descriptors */
406		- spin_lock_irqsave(&mchan->lock, flags);
407		- list_splice_tail_init(&list, &mchan->free);
408		- mchan->completed_cookie = last_cookie;
409		- spin_unlock_irqrestore(&mchan->lock, flags);
410		- }
	418	+ mpc_dma_process_completed(mdma);
411	419	}
412	420
413	421	/* Submit descriptor to hardware */
414	422
...	...	@@ -587,8 +595,11 @@
587	595	}
588	596	spin_unlock_irqrestore(&mchan->lock, iflags);
589	597
590		- if (!mdesc)
	598	+ if (!mdesc) {
	599	+ /* try to free completed descriptors */
	600	+ mpc_dma_process_completed(mdma);
591	601	return NULL;
	602	+ }
592	603
593	604	mdesc->error = 0;
594	605	tcd = mdesc->tcd;