[PATCH v4 2/6] dmaengine: virt-dma: Use lockdep to check locking requirements

Laurent Pinchart
2020-05-13T16:59:58Z

A few virt-dma functions are documented as requiring the vc.lock to be
held by the caller. Check this with lockdep.

The vchan_vdesc_fini() and vchan_find_desc() functions gain a lockdep
check as well, because, even though they are not documented with this
requirement (and not documented at all for the latter), they touch
fields documented as protected by vc.lock. All callers have been
manually inspected to verify they call the functions with the lock held.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
drivers/dma/virt-dma.c | 2 ++
drivers/dma/virt-dma.h | 10 ++++++++++
2 files changed, 12 insertions(+)

diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c
index 23e33a85f033..1cb36ab3d9c1 100644
--- a/drivers/dma/virt-dma.c
+++ b/drivers/dma/virt-dma.c
@@ -68,6 +68,8 @@ struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
{
struct virt_dma_desc *vd;

+ lockdep_assert_held(&vc->lock);
+
list_for_each_entry(vd, &vc->desc_issued, node)
if (vd->tx.cookie == cookie)
return vd;
diff --git a/drivers/dma/virt-dma.h b/drivers/dma/virt-dma.h
index e9f5250fbe4d..59d9eabc8b67 100644
--- a/drivers/dma/virt-dma.h
+++ b/drivers/dma/virt-dma.h
@@ -81,6 +81,8 @@ static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan
*/
static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
{
+ lockdep_assert_held(&vc->lock);
+
list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
return !list_empty(&vc->desc_issued);
}
@@ -96,6 +98,8 @@ static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
dma_cookie_t cookie;

+ lockdep_assert_held(&vc->lock);
+
cookie = vd->tx.cookie;
dma_cookie_complete(&vd->tx);
dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
@@ -146,6 +150,8 @@ static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
{
struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);

+ lockdep_assert_held(&vc->lock);
+
list_add_tail(&vd->node, &vc->desc_terminated);

if (vc->cyclic == vd)
@@ -160,6 +166,8 @@ static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
*/
static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
{
+ lockdep_assert_held(&vc->lock);
+
return list_first_entry_or_null(&vc->desc_issued,
struct virt_dma_desc, node);
}
@@ -177,6 +185,8 @@ static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
struct list_head *head)
{
+ lockdep_assert_held(&vc->lock);
+
list_splice_tail_init(&vc->desc_allocated, head);
list_splice_tail_init(&vc->desc_submitted, head);
list_splice_tail_init(&vc->desc_issued, head);