linux-kernel - [RFC PATCH 02/12] mm/cma: clean up flag handling a bit

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Message-ID: <20250915195153.462039-3-fvdl@google.com>
Date: Mon, 15 Sep 2025 19:51:43 +0000
From: Frank van der Linden <fvdl@...gle.com>
To: akpm@...ux-foundation.org, muchun.song@...ux.dev, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Cc: hannes@...xchg.org, david@...hat.com, roman.gushchin@...ux.dev, 
	Frank van der Linden <fvdl@...gle.com>
Subject: [RFC PATCH 02/12] mm/cma: clean up flag handling a bit

Atomic bit operations aren't needed for the cma flags
field, so switch their manipulation over to normal
AND/OR operations.

Also export the bit values in linux/cma.h, as we will
be adding publicly used values later.

No functional change.

Signed-off-by: Frank van der Linden <fvdl@...gle.com>
---
 include/linux/cma.h | 12 ++++++++++++
 mm/cma.c            | 16 ++++++++--------
 mm/cma.h            |  7 -------
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/include/linux/cma.h b/include/linux/cma.h
index 62d9c1cf6326..5c3fdc5da908 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -20,6 +20,18 @@
 #define CMA_MIN_ALIGNMENT_PAGES pageblock_nr_pages
 #define CMA_MIN_ALIGNMENT_BYTES (PAGE_SIZE * CMA_MIN_ALIGNMENT_PAGES)
 
+enum cma_flags {
+	__CMA_RESERVE_PAGES_ON_ERROR,
+	__CMA_ZONES_VALID,
+	__CMA_ZONES_INVALID,
+	__CMA_ACTIVATED,
+};
+
+#define CMA_RESERVE_PAGES_ON_ERROR	BIT(__CMA_RESERVE_PAGES_ON_ERROR)
+#define CMA_ZONES_VALID			BIT(__CMA_ZONES_VALID)
+#define CMA_ZONES_INVALID		BIT(__CMA_ZONES_INVALID)
+#define CMA_ACTIVATED			BIT(__CMA_ACTIVATED)
+
 struct cma;
 
 extern unsigned long totalcma_pages;
diff --git a/mm/cma.c b/mm/cma.c
index 2ffa4befb99a..549d85b2e3a3 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -111,8 +111,8 @@ bool cma_validate_zones(struct cma *cma)
 	 * check has already been done. If neither is set, the
 	 * check has not been performed yet.
 	 */
-	valid_bit_set = test_bit(CMA_ZONES_VALID, &cma->flags);
-	if (valid_bit_set || test_bit(CMA_ZONES_INVALID, &cma->flags))
+	valid_bit_set = (cma->flags & CMA_ZONES_VALID);
+	if (valid_bit_set || (cma->flags & CMA_ZONES_INVALID))
 		return valid_bit_set;
 
 	for (r = 0; r < cma->nranges; r++) {
@@ -126,12 +126,12 @@ bool cma_validate_zones(struct cma *cma)
 		 */
 		WARN_ON_ONCE(!pfn_valid(base_pfn));
 		if (pfn_range_intersects_zones(cma->nid, base_pfn, cmr->count)) {
-			set_bit(CMA_ZONES_INVALID, &cma->flags);
+			cma->flags |= CMA_ZONES_INVALID;
 			return false;
 		}
 	}
 
-	set_bit(CMA_ZONES_VALID, &cma->flags);
+	cma->flags |= CMA_ZONES_VALID;
 
 	return true;
 }
@@ -176,7 +176,7 @@ static void __init cma_activate_area(struct cma *cma)
 	INIT_HLIST_HEAD(&cma->mem_head);
 	spin_lock_init(&cma->mem_head_lock);
 #endif
-	set_bit(CMA_ACTIVATED, &cma->flags);
+	cma->flags |= CMA_ACTIVATED;
 
 	return;
 
@@ -185,7 +185,7 @@ static void __init cma_activate_area(struct cma *cma)
 		bitmap_free(cma->ranges[r].bitmap);
 
 	/* Expose all pages to the buddy, they are useless for CMA. */
-	if (!test_bit(CMA_RESERVE_PAGES_ON_ERROR, &cma->flags)) {
+	if (!(cma->flags & CMA_RESERVE_PAGES_ON_ERROR)) {
 		for (r = 0; r < allocrange; r++) {
 			cmr = &cma->ranges[r];
 			end_pfn = cmr->base_pfn + cmr->count;
@@ -211,7 +211,7 @@ core_initcall(cma_init_reserved_areas);
 
 void __init cma_reserve_pages_on_error(struct cma *cma)
 {
-	set_bit(CMA_RESERVE_PAGES_ON_ERROR, &cma->flags);
+	cma->flags |= CMA_RESERVE_PAGES_ON_ERROR;
 }
 
 static int __init cma_new_area(const char *name, phys_addr_t size,
@@ -1085,7 +1085,7 @@ void __init *cma_reserve_early(struct cma *cma, unsigned long size)
 	/*
 	 * Can only be called early in init.
 	 */
-	if (test_bit(CMA_ACTIVATED, &cma->flags))
+	if (cma->flags & CMA_ACTIVATED)
 		return NULL;
 
 	if (!IS_ALIGNED(size, CMA_MIN_ALIGNMENT_BYTES))
diff --git a/mm/cma.h b/mm/cma.h
index c70180c36559..25b696774c6a 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -64,13 +64,6 @@ struct cma {
 	int nid;
 };
 
-enum cma_flags {
-	CMA_RESERVE_PAGES_ON_ERROR,
-	CMA_ZONES_VALID,
-	CMA_ZONES_INVALID,
-	CMA_ACTIVATED,
-};
-
 extern struct cma cma_areas[MAX_CMA_AREAS];
 extern unsigned int cma_area_count;
 
-- 
2.51.0.384.g4c02a37b29-goog