linux-kernel - [PATCH v2 1/2] err.h: Add ERR_PTR_PCPU(), PTR_ERR_PCPU() and IS_ERR

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Message-ID: <20240818210235.33481-1-ubizjak@gmail.com>
Date: Sun, 18 Aug 2024 23:01:51 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v2 1/2] err.h: Add ERR_PTR_PCPU(), PTR_ERR_PCPU() and IS_ERR_PCPU() macros

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@...il.com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Andrew Morton <akpm@...ux-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