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percpu: introduce PERCPU_PTR() macro

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Introduce PERCPU_PTR() macro to cast the percpu pointer from the percpu
address space to a generic (kernel) address space.  Use it in
per_cpu_ptr() and related SHIFT_PERCPU_PTR() macros.

Also remove common knowledge from SHIFT_PERCPU_PTR() comment, "weird cast"
is just a standard way to inform sparse of a cast from the percpu address
space to a generic address space.

Link: https://lkml.kernel.org/r/20241021080856.48746-2-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Uros Bizjak 2024-10-21 10:07:37 +02:00 committed by Andrew Morton
parent 74ef070e32
commit 001217defd
1 changed files with 7 additions and 5 deletions
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12
include/linux/percpu-defs.h
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@ -220,15 +220,17 @@ do { \
(void)__vpp_verify; \
} while (0)
#define PERCPU_PTR(__p) \
(typeof(*(__p)) __force __kernel *)(__p);
#ifdef CONFIG_SMP
/*
* Add an offset to a pointer but keep the pointer as-is. Use RELOC_HIDE()
* to prevent the compiler from making incorrect assumptions about the
* pointer value. The weird cast keeps both GCC and sparse happy.
* Add an offset to a pointer. Use RELOC_HIDE() to prevent the compiler
* from making incorrect assumptions about the pointer value.
*/
#define SHIFT_PERCPU_PTR(__p, __offset) \
RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset))
RELOC_HIDE(PERCPU_PTR(__p), (__offset))
#define per_cpu_ptr(ptr, cpu) \
({ \
@ -258,7 +260,7 @@ do { \
({ \
(void)(cpu); \
__verify_pcpu_ptr(ptr); \
(typeof(*(ptr)) __kernel __force *)(ptr); \
PERCPU_PTR(ptr); \
})
#define raw_cpu_ptr(ptr) per_cpu_ptr(ptr, 0)