s390/percpu: implement this_cpu_xchg() (28634a07) · Commits · 戴 / test

The generic variant has a local_irq_save/restore pair which is quite expensive. It is sufficient to disable preemption, which is a no-op with !CONFIG_PREEMPT and then use the regular xchg macro. Signed-off-by:

Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by:

Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/percpu.h

+18 −0

Original line number	Diff line number	Diff line
		@@ -84,6 +84,24 @@ do { \
		#define this_cpu_cmpxchg_4(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval)
		#define this_cpu_cmpxchg_8(pcp, oval, nval) arch_this_cpu_cmpxchg(pcp, oval, nval)

		#define arch_this_cpu_xchg(pcp, nval) \
		({ \
		typeof(pcp) *ptr__; \
		typeof(pcp) ret__; \
		preempt_disable(); \
		ptr__ = __this_cpu_ptr(&(pcp)); \
		ret__ = xchg(ptr__, nval); \
		preempt_enable(); \
		ret__; \
		})

		#define this_cpu_xchg_1(pcp, nval) arch_this_cpu_xchg(pcp, nval)
		#define this_cpu_xchg_2(pcp, nval) arch_this_cpu_xchg(pcp, nval)
		#define this_cpu_xchg_4(pcp, nval) arch_this_cpu_xchg(pcp, nval)
		#ifdef CONFIG_64BIT
		#define this_cpu_xchg_8(pcp, nval) arch_this_cpu_xchg(pcp, nval)
		#endif

		#include <asm-generic/percpu.h>

		#endif /* __ARCH_S390_PERCPU__ */

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