mm: cma: use CMA_MAX_NAME to define the length of cma name array

CMA_MAX_NAME should be visible to CMA's users as they might need it to set
the name of CMA areas and avoid hardcoding the size locally.
So this patch moves CMA_MAX_NAME from local header file to include/linux
header file and removes the hardcode in both hugetlb.c and contiguous.c.
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

include/linux/cma.h

@@ -18,6 +18,8 @@
 
 #endif
 
+#define CMA_MAX_NAME 64
+
 struct cma;
 
 extern unsigned long totalcma_pages;

kernel/dma/contiguous.c

@@ -119,7 +119,7 @@ void __init dma_pernuma_cma_reserve(void)
 
 	for_each_online_node(nid) {
 		int ret;
-		char name[20];
+		char name[CMA_MAX_NAME];
 		struct cma **cma = &dma_contiguous_pernuma_area[nid];
 
 		snprintf(name, sizeof(name), "pernuma%d", nid);

mm/cma.h

@@ -4,8 +4,6 @@
 
 #include <linux/debugfs.h>
 
-#define CMA_MAX_NAME 64
-
 struct cma {
 	unsigned long   base_pfn;
 	unsigned long   count;

mm/hugetlb.c

@@ -5683,12 +5683,12 @@ void __init hugetlb_cma_reserve(int order)
 	reserved = 0;
 	for_each_node_state(nid, N_ONLINE) {
 		int res;
-		char name[20];
+		char name[CMA_MAX_NAME];
 
 		size = min(per_node, hugetlb_cma_size - reserved);
 		size = round_up(size, PAGE_SIZE << order);
 
-		snprintf(name, 20, "hugetlb%d", nid);
+		snprintf(name, sizeof(name), "hugetlb%d", nid);
 		res = cma_declare_contiguous_nid(0, size, 0, PAGE_SIZE << order,
 						 0, false, name,
 						 &hugetlb_cma[nid], nid);