dmaengine: reference counted unmap data

Hang a common 'unmap' object off of dma descriptors for the purpose of
providing a unified unmapping interface.  The lifetime of a mapping may
span multiple descriptors, so these unmap objects are reference counted
by related descriptor.

Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Tomasz Figa <t.figa@samsung.com>
Cc: Dave Jiang <dave.jiang@intel.com>
[bzolnier: fix IS_ENABLED() check]
[bzolnier: fix release ordering in dmaengine_destroy_unmap_pool()]
[bzolnier: fix check for success in dmaengine_init_unmap_pool()]
[bzolnier: use mempool_free() instead of kmem_cache_free()]
[bzolnier: add missing unmap->len initializations]
[bzolnier: add __init tag to dmaengine_init_unmap_pool()]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
[djbw: move DMAENGINE=n support to this patch for async_tx]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 9070050fbcd8..2fe855a7cab1 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -464,9 +464,12 @@ static inline void dma_set_unmap(struct dma_async_tx_descriptor *tx,
         tx->unmap = unmap;
 }
 
+void dmaengine_unmap_put(struct dmaengine_unmap_data *unmap);
+
 static inline void dma_descriptor_unmap(struct dma_async_tx_descriptor *tx)
 {
         if (tx->unmap) {
+                dmaengine_unmap_put(tx->unmap);
                 tx->unmap = NULL;
         }
 }