dma-debug: introduce dma_debug_disabled

Add a helper function which returns whether the DMA debugging API is
disabled, right now we only check for global_disable, but in order to
accommodate early callers of the DMA-API, we will check for more
initialization flags in the next patch.

Signed-off-by: Florian Fainelli <[e-mail]>
Cc: Dan Williams <[e-mail]>
Cc: Jiri Kosina <[e-mail]>
Cc: Horia Geanta <[e-mail]>
Cc: Brian Norris <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

lib/dma-debug.c

···
 /* Global disable flag - will be set in case of an error */
 static u32 global_disable __read_mostly;
 
+static inline bool dma_debug_disabled(void)
+{
+	return global_disable;
+}
+
 /* Global error count */
 static u32 error_count;
 
···
 	struct dma_debug_entry *uninitialized_var(entry);
 	int count;
 
-	if (global_disable)
+	if (dma_debug_disabled())
 		return 0;
 
 	switch (action) {
···
 {
 	struct notifier_block *nb;
 
-	if (global_disable)
+	if (dma_debug_disabled())
 		return;
 
 	nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
···
 {
 	int i;
 
-	if (global_disable)
+	if (dma_debug_disabled())
 		return;
 
 	for (i = 0; i < HASH_SIZE; ++i) {
···
 {
 	struct dma_debug_entry *entry;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	if (dma_mapping_error(dev, dma_addr))
···
 	struct hash_bucket *bucket;
 	unsigned long flags;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	ref.dev = dev;
···
 		.direction      = direction,
 	};
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	if (map_single)
···
 	struct scatterlist *s;
 	int i;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	for_each_sg(sg, s, mapped_ents, i) {
···
 	struct scatterlist *s;
 	int mapped_ents = 0, i;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	for_each_sg(sglist, s, nelems, i) {
···
 {
 	struct dma_debug_entry *entry;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	if (unlikely(virt == NULL))
···
 		.direction      = DMA_BIDIRECTIONAL,
 	};
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	check_unmap(&ref);
···
 {
 	struct dma_debug_entry ref;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	ref.type         = dma_debug_single;
···
 {
 	struct dma_debug_entry ref;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	ref.type         = dma_debug_single;
···
 {
 	struct dma_debug_entry ref;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	ref.type         = dma_debug_single;
···
 {
 	struct dma_debug_entry ref;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	ref.type         = dma_debug_single;
···
 	struct scatterlist *s;
 	int mapped_ents = 0, i;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	for_each_sg(sg, s, nelems, i) {
···
 	struct scatterlist *s;
 	int mapped_ents = 0, i;
 
-	if (unlikely(global_disable))
+	if (unlikely(dma_debug_disabled()))
 		return;
 
 	for_each_sg(sg, s, nelems, i) {