mm_zone: Generalise has_managed_dma()

It would be useful to be able to check for potential DMA pages beyond
just ZONE_DMA - generalise the existing has_managed_dma() function to
allow checking other zones too.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/bd002d2351074e57be1ca08f03f333debac658fb.1768230104.git.robin.murphy@arm.com

Author: rmurphy-arm

include/linux/mmzone.h

@@ -1648,14 +1648,15 @@ static inline int is_highmem(const struct zone *zone)
 	return is_highmem_idx(zone_idx(zone));
 }
 
-#ifdef CONFIG_ZONE_DMA
-bool has_managed_dma(void);
-#else
+bool has_managed_zone(enum zone_type zone);
 static inline bool has_managed_dma(void)
 {
+#ifdef CONFIG_ZONE_DMA
+	return has_managed_zone(ZONE_DMA);
+#else
 	return false;
-}
 #endif
+}
 
 
 #ifndef CONFIG_NUMA

mm/page_alloc.c

@@ -7418,20 +7418,16 @@ bool put_page_back_buddy(struct page *page)
 }
 #endif
 
-#ifdef CONFIG_ZONE_DMA
-bool has_managed_dma(void)
+bool has_managed_zone(enum zone_type zone)
 {
 	struct pglist_data *pgdat;
 
 	for_each_online_pgdat(pgdat) {
-		struct zone *zone = &pgdat->node_zones[ZONE_DMA];
-
-		if (managed_zone(zone))
+		if (managed_zone(&pgdat->node_zones[zone]))
 			return true;
 	}
 	return false;
 }
-#endif /* CONFIG_ZONE_DMA */
 
 #ifdef CONFIG_UNACCEPTED_MEMORY