Commit 001217de authored by Uros Bizjak's avatar Uros Bizjak Committed by Andrew Morton
Browse files

percpu: introduce PERCPU_PTR() macro 

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: default avatarUros Bizjak <ubizjak@gmail.com>
Acked-by: default avatarChristoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 74ef070e

include/linux/percpu-defs.h

+7 −5
Original line number Diff line number Diff line
@@ -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)