[PATCH 5.15.y 04/10] dma-direct: warn if there is no pool for force unencrypted allocations

[Sasha Levin <sashal@kernel.org>]

From: Christoph Hellwig <hch@lst.de>

[ Upstream commit 78bc72787ab9e638173aeb1f589578105d3a43c9 ]

Instead of blindly running into a blocking operation for a non-blocking gfp,
return NULL and spew an error.  Note that Kconfig prevents this for all
currently relevant platforms, and this is just a debug check.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Stable-dep-of: 94a04ad732c9 ("dma-direct: return struct page from dma_direct_alloc_from_pool()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/dma/direct.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 0d6467b6553b7..5a71b6edfd1cd 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -162,6 +162,9 @@ static void *dma_direct_alloc_from_pool(struct device *dev, size_t size,
 	u64 phys_mask;
 	void *ret;
 
+	if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_DMA_COHERENT_POOL)))
+		return NULL;
+
 	gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
 					   &phys_mask);
 	page = dma_alloc_from_pool(dev, size, &ret, gfp, dma_coherent_ok);
@@ -246,8 +249,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 	 * Decrypting memory may block, so allocate the memory from the atomic
 	 * pools if we can't block.
 	 */
-	if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
-	    force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) &&
+	if (force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) &&
 	    !is_swiotlb_for_alloc(dev))
 		return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
 
@@ -357,8 +359,7 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
 	struct page *page;
 	void *ret;
 
-	if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
-	    force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) &&
+	if (force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) &&
 	    !is_swiotlb_for_alloc(dev))
 		return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
 
-- 
2.53.0