[PATCH v3 32/34] dmaengine: hidma: defer callbacks via channel BH

[Allen Pais <allen.lkml@gmail.com>]

Move descriptor callback processing out of the low-level completion
path and schedule it through per-channel BH work. Drain that work while
freeing channels so callbacks cannot outlive channel storage.

Signed-off-by: Allen Pais <allen.lkml@gmail.com>
---
 drivers/dma/qcom/hidma.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c
index c939635be21d..486a2c61a9fb 100644
--- a/drivers/dma/qcom/hidma.c
+++ b/drivers/dma/qcom/hidma.c
@@ -90,7 +90,13 @@ static inline struct hidma_chan *to_hidma_chan(struct dma_chan *dmach)
 
 static void hidma_free(struct hidma_dev *dmadev)
 {
-	INIT_LIST_HEAD(&dmadev->ddev.channels);
+	struct hidma_chan *mchan, *next;
+
+	list_for_each_entry_safe(mchan, next, &dmadev->ddev.channels,
+				 chan.device_node) {
+		dmaengine_kill_bh(&mchan->chan);
+		list_del(&mchan->chan.device_node);
+	}
 }
 
 static unsigned int nr_desc_prm;
@@ -155,6 +161,13 @@ static void hidma_process_completed(struct hidma_chan *mchan)
 	}
 }
 
+static void hidma_chan_bh(struct dma_chan *chan)
+{
+	struct hidma_chan *mchan = to_hidma_chan(chan);
+
+	hidma_process_completed(mchan);
+}
+
 /*
  * Called once for each submitted descriptor.
  * PM is locked once for each descriptor that is currently
@@ -181,7 +194,7 @@ static void hidma_callback(void *data)
 	}
 	spin_unlock_irqrestore(&mchan->lock, irqflags);
 
-	hidma_process_completed(mchan);
+	dmaengine_schedule_bh(&mchan->chan);
 
 	if (queued) {
 		pm_runtime_mark_last_busy(dmadev->ddev.dev);
@@ -203,6 +216,7 @@ static int hidma_chan_init(struct hidma_dev *dmadev, u32 dma_sig)
 	mchan->dmadev = dmadev;
 	mchan->chan.device = ddev;
 	dma_cookie_init(&mchan->chan);
+	dmaengine_init_bh(&mchan->chan, hidma_chan_bh);
 
 	INIT_LIST_HEAD(&mchan->free);
 	INIT_LIST_HEAD(&mchan->prepared);
-- 
2.43.0