Merge tag 'dma-mapping-6.9-2024-03-11' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping updates from Christoph Hellwig:

 - fix leaked pages on dma_set_decrypted() failure (Rick Edgecombe)

 - add a new swiotlb debugfs file (ZhangPeng)

* tag 'dma-mapping-6.9-2024-03-11' of git://git.infradead.org/users/hch/dma-mapping:
  dma-direct: Leak pages on dma_set_decrypted() failure
  swiotlb: add debugfs to track swiotlb transient pool usage

Author: torvalds

include/linux/swiotlb.h

@@ -120,6 +120,8 @@ struct io_tlb_pool {
  *		debugfs.
  * @used_hiwater: The high water mark for total_used.  Used only for reporting
  *		in debugfs.
+ * @transient_nslabs: The total number of slots in all transient pools that
+ *		are currently used across all areas.
  */
 struct io_tlb_mem {
 	struct io_tlb_pool defpool;
@@ -137,6 +139,7 @@ struct io_tlb_mem {
 #ifdef CONFIG_DEBUG_FS
 	atomic_long_t total_used;
 	atomic_long_t used_hiwater;
+	atomic_long_t transient_nslabs;
 #endif
 };
 

kernel/dma/direct.c

@@ -286,7 +286,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 	} else {
 		ret = page_address(page);
 		if (dma_set_decrypted(dev, ret, size))
-			goto out_free_pages;
+			goto out_leak_pages;
 	}
 
 	memset(ret, 0, size);
@@ -307,6 +307,8 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 out_free_pages:
 	__dma_direct_free_pages(dev, page, size);
 	return NULL;
+out_leak_pages:
+	return NULL;
 }
 
 void dma_direct_free(struct device *dev, size_t size,
@@ -367,12 +369,11 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
 
 	ret = page_address(page);
 	if (dma_set_decrypted(dev, ret, size))
-		goto out_free_pages;
+		goto out_leak_pages;
 	memset(ret, 0, size);
 	*dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
 	return page;
-out_free_pages:
-	__dma_direct_free_pages(dev, page, size);
+out_leak_pages:
 	return NULL;
 }
 

kernel/dma/swiotlb.c

@@ -956,6 +956,28 @@ static void dec_used(struct io_tlb_mem *mem, unsigned int nslots)
 }
 #endif /* CONFIG_DEBUG_FS */
 
+#ifdef CONFIG_SWIOTLB_DYNAMIC
+#ifdef CONFIG_DEBUG_FS
+static void inc_transient_used(struct io_tlb_mem *mem, unsigned int nslots)
+{
+	atomic_long_add(nslots, &mem->transient_nslabs);
+}
+
+static void dec_transient_used(struct io_tlb_mem *mem, unsigned int nslots)
+{
+	atomic_long_sub(nslots, &mem->transient_nslabs);
+}
+
+#else /* !CONFIG_DEBUG_FS */
+static void inc_transient_used(struct io_tlb_mem *mem, unsigned int nslots)
+{
+}
+static void dec_transient_used(struct io_tlb_mem *mem, unsigned int nslots)
+{
+}
+#endif /* CONFIG_DEBUG_FS */
+#endif /* CONFIG_SWIOTLB_DYNAMIC */
+
 /**
  * swiotlb_search_pool_area() - search one memory area in one pool
  * @dev:	Device which maps the buffer.
@@ -1170,6 +1192,7 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
 	spin_lock_irqsave(&dev->dma_io_tlb_lock, flags);
 	list_add_rcu(&pool->node, &dev->dma_io_tlb_pools);
 	spin_unlock_irqrestore(&dev->dma_io_tlb_lock, flags);
+	inc_transient_used(mem, pool->nslabs);
 
 found:
 	WRITE_ONCE(dev->dma_uses_io_tlb, true);
@@ -1415,6 +1438,7 @@ static bool swiotlb_del_transient(struct device *dev, phys_addr_t tlb_addr)
 
 	dec_used(dev->dma_io_tlb_mem, pool->nslabs);
 	swiotlb_del_pool(dev, pool);
+	dec_transient_used(dev->dma_io_tlb_mem, pool->nslabs);
 	return true;
 }
 
@@ -1557,6 +1581,23 @@ phys_addr_t default_swiotlb_limit(void)
 }
 
 #ifdef CONFIG_DEBUG_FS
+#ifdef CONFIG_SWIOTLB_DYNAMIC
+static unsigned long mem_transient_used(struct io_tlb_mem *mem)
+{
+	return atomic_long_read(&mem->transient_nslabs);
+}
+
+static int io_tlb_transient_used_get(void *data, u64 *val)
+{
+	struct io_tlb_mem *mem = data;
+
+	*val = mem_transient_used(mem);
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_io_tlb_transient_used, io_tlb_transient_used_get,
+			 NULL, "%llu\n");
+#endif /* CONFIG_SWIOTLB_DYNAMIC */
 
 static int io_tlb_used_get(void *data, u64 *val)
 {
@@ -1605,6 +1646,11 @@ static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem,
 			&fops_io_tlb_used);
 	debugfs_create_file("io_tlb_used_hiwater", 0600, mem->debugfs, mem,
 			&fops_io_tlb_hiwater);
+#ifdef CONFIG_SWIOTLB_DYNAMIC
+	atomic_long_set(&mem->transient_nslabs, 0);
+	debugfs_create_file("io_tlb_transient_nslabs", 0400, mem->debugfs,
+			    mem, &fops_io_tlb_transient_used);
+#endif
 }
 
 static int __init swiotlb_create_default_debugfs(void)