iop-adma: fix lockdep false positive

lockdep correctly identifies a potential recursive locking case for
iop_chan->lock, but in the dependency submission case we expect that the same
class will be acquired for both the parent dependency and the child channel.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/dma/iop-adma.c b/drivers/dma/iop-adma.c
index ce45f3fb0343..9c752bd295e1 100644
--- a/drivers/dma/iop-adma.c
+++ b/drivers/dma/iop-adma.c
@@ -288,7 +288,12 @@ static void iop_adma_tasklet(unsigned long data)
 {
         struct iop_adma_chan *iop_chan = (struct iop_adma_chan *) data;
 
-        spin_lock(&iop_chan->lock);
+        /* lockdep will flag depedency submissions as potentially
+         * recursive locking, this is not the case as a dependency
+         * submission will never recurse a channels submit routine.
+         * There are checks in async_tx.c to prevent this.
+         */
+        spin_lock_nested(&iop_chan->lock, SINGLE_DEPTH_NESTING);
         __iop_adma_slot_cleanup(iop_chan);
         spin_unlock(&iop_chan->lock);
 }