[PATCH v2 4/4] dma-pool: Make sure atomic pool suits device

[Nicolas Saenz Julienne]

When allocating DMA memory from a pool, the core can only guess which
atomic pool will fit a device's constraints. If it doesn't, get a safer
atomic pool and try again.

Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to map to gfp 
mask")
Reported-by: Jeremy Linton <jeremy.lin...@arm.com>
Suggested-by: Robin Murphy <robin.mur...@arm.com>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulie...@suse.de>
---

Changes since v1:
 - Rebase to linus' master

 kernel/dma/pool.c | 57 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 20 deletions(-)

diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 5b9eaa2b498d..d48d9acb585f 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -240,39 +240,56 @@ static inline struct gen_pool *dma_guess_pool(struct 
device *dev,
 void *dma_alloc_from_pool(struct device *dev, size_t size,
                          struct page **ret_page, gfp_t flags)
 {
-       struct gen_pool *pool = dma_guess_pool(dev, NULL);
-       unsigned long val;
+       struct gen_pool *pool = NULL;
+       unsigned long val = 0;
        void *ptr = NULL;
-
-       if (!pool) {
-               WARN(1, "%pGg atomic pool not initialised!\n", &flags);
-               return NULL;
+       phys_addr_t phys;
+
+       while (1) {
+               pool = dma_guess_pool(dev, pool);
+               if (!pool) {
+                       WARN(1, "Failed to get suitable pool for %s\n",
+                            dev_name(dev));
+                       break;
+               }
+
+               val = gen_pool_alloc(pool, size);
+               if (!val)
+                       continue;
+
+               phys = gen_pool_virt_to_phys(pool, val);
+               if (dma_coherent_ok(dev, phys, size))
+                       break;
+
+               gen_pool_free(pool, val, size);
+               val = 0;
        }
 
-       val = gen_pool_alloc(pool, size);
-       if (likely(val)) {
-               phys_addr_t phys = gen_pool_virt_to_phys(pool, val);
 
+       if (val) {
                *ret_page = pfn_to_page(__phys_to_pfn(phys));
                ptr = (void *)val;
                memset(ptr, 0, size);
-       } else {
-               WARN_ONCE(1, "DMA coherent pool depleted, increase size "
-                            "(recommended min coherent_pool=%zuK)\n",
-                         gen_pool_size(pool) >> 9);
+
+               if (gen_pool_avail(pool) < atomic_pool_size)
+                       schedule_work(&atomic_pool_work);
        }
-       if (gen_pool_avail(pool) < atomic_pool_size)
-               schedule_work(&atomic_pool_work);
 
        return ptr;
 }
 
 bool dma_free_from_pool(struct device *dev, void *start, size_t size)
 {
-       struct gen_pool *pool = dma_guess_pool(dev, NULL);
+       struct gen_pool *pool = NULL;
 
-       if (!pool || !gen_pool_has_addr(pool, (unsigned long)start, size))
-               return false;
-       gen_pool_free(pool, (unsigned long)start, size);
-       return true;
+       while (1) {
+               pool = dma_guess_pool(dev, pool);
+               if (!pool)
+                       return false;
+
+               if (gen_pool_has_addr(pool, (unsigned long)start, size)) {
+                       gen_pool_free(pool, (unsigned long)start, size);
+                       return true;
+               }
+       }
 }
-- 
2.27.0