linux-kernel - [PATCH v8 3/3] mm: cma: use CMA_MAX_NAME to define the length of cma name array

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Date:   Mon, 24 Aug 2020 11:03:09 +1200
From:   Barry Song <song.bao.hua@...ilicon.com>
To:     <hch@....de>, <m.szyprowski@...sung.com>, <robin.murphy@....com>,
        <will@...nel.org>, <ganapatrao.kulkarni@...ium.com>,
        <catalin.marinas@....com>, <akpm@...ux-foundation.org>
CC:     <iommu@...ts.linux-foundation.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <prime.zeng@...ilicon.com>,
        <huangdaode@...wei.com>, <linuxarm@...wei.com>,
        Barry Song <song.bao.hua@...ilicon.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Roman Gushchin <guro@...com>
Subject: [PATCH v8 3/3] 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.

Cc: Mike Kravetz <mike.kravetz@...cle.com>
Cc: Roman Gushchin <guro@...com>
Cc: Christoph Hellwig <hch@....de>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Will Deacon <will@...nel.org>
Cc: Robin Murphy <robin.murphy@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Barry Song <song.bao.hua@...ilicon.com>
---
 this patch is fixing the magic number issue with respect to Will's comment here:
 https://lore.kernel.org/linux-iommu/4ab78767553f48a584217063f6f24eb9@hisilicon.com/

 include/linux/cma.h     | 2 ++
 kernel/dma/contiguous.c | 2 +-
 mm/cma.h                | 2 --
 mm/hugetlb.c            | 4 ++--
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/cma.h b/include/linux/cma.h
index 6ff79fefd01f..217999c8a762 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -18,6 +18,8 @@
 
 #endif
 
+#define CMA_MAX_NAME 64
+
 struct cma;
 
 extern unsigned long totalcma_pages;
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index aa53384fd7dc..f4c150810fd2 100644
--- a/kernel/dma/contiguous.c
+++ b/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);
diff --git a/mm/cma.h b/mm/cma.h
index 20f6e24bc477..42ae082cb067 100644
--- a/mm/cma.h
+++ b/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;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a301c2d672bf..9eec0ea9ba68 100644
--- a/mm/hugetlb.c
+++ b/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);
-- 
2.27.0