[PATCH v2 1/2] err.h: Add ERR_PTR_PCPU(), PTR_ERR_PCPU() and IS_ERR_PCPU() macros

[PATCH v2 1/2] err.h: Add ERR_PTR_PCPU(), PTR_ERR_PCPU() and IS_ERR_PCPU() macros

[Uros Bizjak]

Add ERR_PTR_PCPU(), PTR_ERR_PCPU() and IS_ERR_PCPU() macros that
operate on pointers in the percpu address space.

These macros remove the need for (__force void *) function
argument casts (to avoid sparse -Wcast-from-as warnings).

The patch will also avoid future build errors due to pointer address
space mismatch with enabled strict percpu address space checks.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
v2: Implement as macros to avoid powerpc build failure
---
 include/linux/err.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/err.h b/include/linux/err.h
index b5d9bb2a2349..a4dacd745fcf 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -41,6 +41,9 @@ static inline void * __must_check ERR_PTR(long error)
 	return (void *) error;
 }
 
+/* Return the pointer in the percpu address space. */
+#define ERR_PTR_PCPU(error) ((void __percpu *)(unsigned long)ERR_PTR(error))
+
 /**
  * PTR_ERR - Extract the error code from an error pointer.
  * @ptr: An error pointer.
@@ -51,6 +54,9 @@ static inline long __must_check PTR_ERR(__force const void *ptr)
 	return (long) ptr;
 }
 
+/* Read an error pointer from the percpu address space. */
+#define PTR_ERR_PCPU(ptr) (PTR_ERR((const void *)(__force const unsigned long)(ptr)))
+
 /**
  * IS_ERR - Detect an error pointer.
  * @ptr: The pointer to check.
@@ -61,6 +67,9 @@ static inline bool __must_check IS_ERR(__force const void *ptr)
 	return IS_ERR_VALUE((unsigned long)ptr);
 }
 
+/* Read an error pointer from the percpu address space. */
+#define IS_ERR_PCPU(ptr) (IS_ERR((const void *)(__force const unsigned long)(ptr)))
+
 /**
  * IS_ERR_OR_NULL - Detect an error pointer or a null pointer.
  * @ptr: The pointer to check.
-- 
2.42.0

[PATCH v2 2/2] mm/kmemleak: Use IS_ERR_PCPU() for pointer in the percpu address space

[Uros Bizjak]

Use IS_ERR_PCPU() instead of IS_ERR() for pointers in the percpu address
space. The patch also fixes following sparse warnings:

kmemleak.c:1063:39: warning: cast removes address space '__percpu' of expression
kmemleak.c:1138:37: warning: cast removes address space '__percpu' of expression

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 mm/kmemleak.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 764b08100570..fa468809d043 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1059,8 +1059,8 @@ void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
 	 * Percpu allocations are only scanned and not reported as leaks
 	 * (min_count is set to 0).
 	 */
-	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
-		create_object_percpu((unsigned long)ptr, size, 0, gfp);
+	if (kmemleak_enabled && ptr && !IS_ERR_PCPU(ptr))
+		create_object_percpu((__force unsigned long)ptr, size, 0, gfp);
 }
 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
 
@@ -1134,8 +1134,8 @@ void __ref kmemleak_free_percpu(const void __percpu *ptr)
 {
 	pr_debug("%s(0x%px)\n", __func__, ptr);
 
-	if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
-		delete_object_full((unsigned long)ptr, OBJECT_PERCPU);
+	if (kmemleak_free_enabled && ptr && !IS_ERR_PCPU(ptr))
+		delete_object_full((__force unsigned long)ptr, OBJECT_PERCPU);
 }
 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
 
-- 
2.42.0

Re: [PATCH v2 1/2] err.h: Add ERR_PTR_PCPU(), PTR_ERR_PCPU() and IS_ERR_PCPU() macros

[Catalin Marinas]

On Sun, Aug 18, 2024 at 11:01:51PM +0200, Uros Bizjak wrote:
> Add ERR_PTR_PCPU(), PTR_ERR_PCPU() and IS_ERR_PCPU() macros that
> operate on pointers in the percpu address space.
> 
> These macros remove the need for (__force void *) function
> argument casts (to avoid sparse -Wcast-from-as warnings).
> 
> The patch will also avoid future build errors due to pointer address
> space mismatch with enabled strict percpu address space checks.
> 
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH v2 2/2] mm/kmemleak: Use IS_ERR_PCPU() for pointer in the percpu address space

[Catalin Marinas]

On Sun, Aug 18, 2024 at 11:01:52PM +0200, Uros Bizjak wrote:
> Use IS_ERR_PCPU() instead of IS_ERR() for pointers in the percpu address
> space. The patch also fixes following sparse warnings:
> 
> kmemleak.c:1063:39: warning: cast removes address space '__percpu' of expression
> kmemleak.c:1138:37: warning: cast removes address space '__percpu' of expression
> 
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>