dmaengine: virt-dma: Do not call desc_free() under a spin_lock

vchan_vdesc_fini() shouldn't be called under a spin_lock. This is done
in two places, once in vchan_terminate_vdesc() and once in
vchan_synchronize(). Instead of freeing the vdesc right away, collect
the aborted vdescs on a separate list and free them along with the other
vdescs. The terminated descs are also freed in vchan_synchronize as done
before this patch.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20191216105328.15198-5-s.hauer@pengutronix.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>
diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c
index 7ba7128..26e08c7 100644
--- a/drivers/dma/virt-dma.c
+++ b/drivers/dma/virt-dma.c
@@ -138,6 +138,7 @@ void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
 	INIT_LIST_HEAD(&vc->desc_submitted);
 	INIT_LIST_HEAD(&vc->desc_issued);
 	INIT_LIST_HEAD(&vc->desc_completed);
+	INIT_LIST_HEAD(&vc->desc_terminated);
 
 	tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);