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share/man/man9/casuword.9

	.\" Copyright (c) 2014 The FreeBSD Foundation			.\" Copyright (c) 2014, 2019 The FreeBSD Foundation
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	.\" Konstantin Belousov <kib@FreeBSD.org> under sponsorship			.\" Konstantin Belousov <kib@FreeBSD.org> under sponsorship
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	.\" $FreeBSD$			.\" $FreeBSD$
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	.Dd October 21, 2014			.Dd April 19, 2019
	.Dt CASU 9			.Dt CASU 9
	.Os			.Os
	.Sh NAME			.Sh NAME
	.Nm casueword ,			.Nm casueword ,
	.Nm casueword32 ,			.Nm casueword32 ,
	.Nm casuword ,			.Nm casuword ,
	.Nm casuword32			.Nm casuword32
	.Nd fetch, compare and store data from user-space			.Nd fetch, compare and store data from user-space
	.Sh SYNOPSIS			.Sh SYNOPSIS
	.In sys/types.h			.In sys/types.h
	.In sys/systm.h			.In sys/systm.h
	.Ft int			.Ft int
	.Fn casueword "volatile u_long base" "u_long oldval" "u_long oldvalp" "u_long newval"			.Fo casueword
				.Fa "volatile u_long *base"
				.Fa "u_long oldval"
				.Fa "u_long *oldvalp"
				.Fa "u_long newval"
				.Fc
	.Ft int			.Ft int
	.Fn casueword32 "volatile uint32_t base" "uint32_t oldval" "uint32_t oldvalp" "uint32_t newval"			.Fo casueword32
				.Fa "volatile uint32_t *base"
				.Fa "uint32_t oldval"
				.Fa "uint32_t *oldvalp"
				.Fa "uint32_t newval"
				.Fc
	.Ft u_long			.Ft u_long
	.Fn casuword "volatile u_long *base" "u_long oldval" "u_long newval"			.Fo casuword
				.Fa "volatile u_long *base"
				.Fa "u_long oldval"
				.Fa "u_long newval"
				.Fc
	.Ft uint32_t			.Ft uint32_t
	.Fn casuword32 "volatile uint32_t *base" "uint32_t oldval" "uint32_t newval"			.Fo casuword32
				.Fa "volatile uint32_t *base"
				.Fa "uint32_t oldval"
				.Fa "uint32_t newval"
				.Fc
	.Sh DESCRIPTION			.Sh DESCRIPTION
	The			The
	.Nm			.Nm
	functions are designed to perform atomic compare-and-swap operation on			functions are designed to perform atomic compare-and-swap operation on
	the value in the usermode memory of the current process.			the value in the usermode memory of the current process.
	.Pp			.Pp
	The			The
	.Nm			.Nm
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	.Fn casuword			.Fn casuword
	and			and
	.Fn casuword32			.Fn casuword32
	functions return the data fetched or -1 on failure.			functions return the data fetched or -1 on failure.
	The			The
	.Fn casueword			.Fn casueword
	and			and
	.Fn casueword32			.Fn casueword32
	functions return 0 on success and -1 on failure.			functions return 0 on success, -1 on failure to access memory,
				and 1 when comparision or store failed.
				markjUnsubmitted Done Inline Actions Typo in "comparison." markj: Typo in "comparison."
				The store can fail on load-linked/store-conditional architectures.
	.Sh SEE ALSO			.Sh SEE ALSO
	.Xr atomic 9 ,			.Xr atomic 9 ,
	.Xr fetch 9 ,			.Xr fetch 9 ,
	.Xr store 9			.Xr store 9