[PATCH] mm: cma: make mm/cma.h self-contained and conditionalize includes

[PATCH] mm: cma: make mm/cma.h self-contained and conditionalize includes

[Eamon Sippy]

mm/cma.h uses types from <linux/spinlock.h>, <linux/mutex.h>,
<linux/atomic.h> and <linux/list.h> without explicitly including them,
violating the kernel header self-containment guidelines.

<linux/debugfs.h> and <linux/kobject.h> are also included unconditionally
even though they are only needed under CONFIG_CMA_DEBUGFS and
CONFIG_CMA_SYSFS respectively. Move the struct cma_kobject definition and
<linux/kobject.h> inside the CONFIG_CMA_SYSFS block, and move
<linux/debugfs.h> inside CONFIG_CMA_DEBUGFS.

Remove spurious trailing semicolons after the empty inline function bodies
in the CONFIG_CMA_SYSFS #else branch.

Add <linux/cma.h> so that MAX_CMA_AREAS and CMA_MAX_NAME are always
available when this header is included.

Signed-off-by: Eamon Sippy <eamon112009@gmail.com>
---
 mm/cma.h | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/mm/cma.h b/mm/cma.h
index c70180c36559..0a1cb0141756 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -2,13 +2,24 @@
 #ifndef __MM_CMA_H__
 #define __MM_CMA_H__
 
+#include <linux/atomic.h>
+#include <linux/cma.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+
+#ifdef CONFIG_CMA_DEBUGFS
 #include <linux/debugfs.h>
+#endif
+
+#ifdef CONFIG_CMA_SYSFS
 #include <linux/kobject.h>
 
 struct cma_kobject {
 	struct kobject kobj;
 	struct cma *cma;
 };
+#endif
 
 /*
  * Multi-range support. This can be useful if the size of the allocation
@@ -37,10 +48,10 @@ struct cma_memrange {
 #define CMA_MAX_RANGES 8
 
 struct cma {
-	unsigned long   count;
-	unsigned long	available_count;
+	unsigned long count;
+	unsigned long available_count;
 	unsigned int order_per_bit; /* Order of pages represented by one bit */
-	spinlock_t	lock;
+	spinlock_t lock;	/* protects allocation bitmap */
 	struct mutex alloc_mutex;
 #ifdef CONFIG_CMA_DEBUGFS
 	struct hlist_head mem_head;
@@ -86,10 +97,11 @@ void cma_sysfs_account_fail_pages(struct cma *cma, unsigned long nr_pages);
 void cma_sysfs_account_release_pages(struct cma *cma, unsigned long nr_pages);
 #else
 static inline void cma_sysfs_account_success_pages(struct cma *cma,
-						   unsigned long nr_pages) {};
+						   unsigned long nr_pages) {}
 static inline void cma_sysfs_account_fail_pages(struct cma *cma,
-						unsigned long nr_pages) {};
+						unsigned long nr_pages) {}
 static inline void cma_sysfs_account_release_pages(struct cma *cma,
-						   unsigned long nr_pages) {};
+						   unsigned long nr_pages) {}
 #endif
+
 #endif
-- 
2.43.0

Re: [PATCH] mm: cma: make mm/cma.h self-contained and conditionalize includes

[Barry Song]

On Sat, Aug 15, 2026 at 4:41 PM Eamon Sippy <eamon112009@gmail.com> wrote:
>
> mm/cma.h uses types from <linux/spinlock.h>, <linux/mutex.h>,
> <linux/atomic.h> and <linux/list.h> without explicitly including them,
> violating the kernel header self-containment guidelines.
>
> <linux/debugfs.h> and <linux/kobject.h> are also included unconditionally
> even though they are only needed under CONFIG_CMA_DEBUGFS and
> CONFIG_CMA_SYSFS respectively. Move the struct cma_kobject definition and
> <linux/kobject.h> inside the CONFIG_CMA_SYSFS block, and move
> <linux/debugfs.h> inside CONFIG_CMA_DEBUGFS.
>
> Remove spurious trailing semicolons after the empty inline function bodies
> in the CONFIG_CMA_SYSFS #else branch.
>
> Add <linux/cma.h> so that MAX_CMA_AREAS and CMA_MAX_NAME are always
> available when this header is included.
>
> Signed-off-by: Eamon Sippy <eamon112009@gmail.com>
[...]
> +       unsigned long available_count;
>         unsigned int order_per_bit; /* Order of pages represented by one bit */
> -       spinlock_t      lock;
> +       spinlock_t lock;        /* protects allocation bitmap */

I’m not convinced this lock is only for protecting the bitmap. It also
protects things such as cma->available_count and the allocation checks
around page_range_contiguous(). Could we drop the added comment or
use a more accurate description?

>         struct mutex alloc_mutex;

Best Regards
Barry

[PATCH v2] mm: cma: make mm/cma.h self-contained and conditionalize includes

[Eamon Sippy]

mm/cma.h uses types from <linux/spinlock.h>, <linux/mutex.h>,
<linux/atomic.h> and <linux/list.h> without explicitly including them,
violating the kernel header self-containment guidelines.

<linux/debugfs.h> and <linux/kobject.h> are also included unconditionally
even though they are only needed under CONFIG_CMA_DEBUGFS and
CONFIG_CMA_SYSFS respectively. Move the struct cma_kobject definition and
<linux/kobject.h> inside the CONFIG_CMA_SYSFS block, and move
<linux/debugfs.h> inside CONFIG_CMA_DEBUGFS.

Remove spurious trailing semicolons after the empty inline function bodies
in the CONFIG_CMA_SYSFS #else branch.

Add <linux/cma.h> so that MAX_CMA_AREAS and CMA_MAX_NAME are always
available when this header is included.

Changes in v2:
- Drop inaccurate spinlock comment; the lock also protects
  available_count and allocation checks (Barry)

Signed-off-by: Eamon Sippy <eamon112009@gmail.com>
---
 mm/cma.h | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/mm/cma.h b/mm/cma.h
index c70180c36559..68e574b0f951 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -2,13 +2,24 @@
 #ifndef __MM_CMA_H__
 #define __MM_CMA_H__
 
+#include <linux/atomic.h>
+#include <linux/cma.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+
+#ifdef CONFIG_CMA_DEBUGFS
 #include <linux/debugfs.h>
+#endif
+
+#ifdef CONFIG_CMA_SYSFS
 #include <linux/kobject.h>
 
 struct cma_kobject {
 	struct kobject kobj;
 	struct cma *cma;
 };
+#endif
 
 /*
  * Multi-range support. This can be useful if the size of the allocation
@@ -37,10 +48,10 @@ struct cma_memrange {
 #define CMA_MAX_RANGES 8
 
 struct cma {
-	unsigned long   count;
-	unsigned long	available_count;
+	unsigned long count;
+	unsigned long available_count;
 	unsigned int order_per_bit; /* Order of pages represented by one bit */
-	spinlock_t	lock;
+	spinlock_t lock;
 	struct mutex alloc_mutex;
 #ifdef CONFIG_CMA_DEBUGFS
 	struct hlist_head mem_head;
@@ -86,10 +97,11 @@ void cma_sysfs_account_fail_pages(struct cma *cma, unsigned long nr_pages);
 void cma_sysfs_account_release_pages(struct cma *cma, unsigned long nr_pages);
 #else
 static inline void cma_sysfs_account_success_pages(struct cma *cma,
-						   unsigned long nr_pages) {};
+						   unsigned long nr_pages) {}
 static inline void cma_sysfs_account_fail_pages(struct cma *cma,
-						unsigned long nr_pages) {};
+						unsigned long nr_pages) {}
 static inline void cma_sysfs_account_release_pages(struct cma *cma,
-						   unsigned long nr_pages) {};
+						   unsigned long nr_pages) {}
 #endif
+
 #endif
-- 
2.43.0

Re: [PATCH v2] mm: cma: make mm/cma.h self-contained and conditionalize includes

[Barry Song]

On Sat, Aug 15, 2026 at 6:33 PM Eamon Sippy <eamon112009@gmail.com> wrote:
>
> mm/cma.h uses types from <linux/spinlock.h>, <linux/mutex.h>,
> <linux/atomic.h> and <linux/list.h> without explicitly including them,
> violating the kernel header self-containment guidelines.
>
> <linux/debugfs.h> and <linux/kobject.h> are also included unconditionally
> even though they are only needed under CONFIG_CMA_DEBUGFS and
> CONFIG_CMA_SYSFS respectively. Move the struct cma_kobject definition and
> <linux/kobject.h> inside the CONFIG_CMA_SYSFS block, and move
> <linux/debugfs.h> inside CONFIG_CMA_DEBUGFS.
>
> Remove spurious trailing semicolons after the empty inline function bodies
> in the CONFIG_CMA_SYSFS #else branch.
>
> Add <linux/cma.h> so that MAX_CMA_AREAS and CMA_MAX_NAME are always
> available when this header is included.
>
> Changes in v2:
> - Drop inaccurate spinlock comment; the lock also protects
>   available_count and allocation checks (Barry)
>
> Signed-off-by: Eamon Sippy <eamon112009@gmail.com>
> ---

Reviewed-by: Barry Song <baohua@kernel.org>