dma-direct: warn if there is no pool for force unencrypted allocations

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>

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index a13017656ecae34ba9d6b2b6d09119ef43c846b3..84226a764471bfd993446de0f2c12ae9f69b1118 100644 (file)
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -159,6 +159,9 @@ 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);
@@ -243,8 +246,7 @@ 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);
 
@@ -354,8 +356,7 @@ 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);