Differential D32947 Diff 98437 share/man/man9/vm_page_busy.9

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share/man/man9/vm_page_busy.9

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	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR			.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
	.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER			.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT			.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY			.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH			.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
	.\" DAMAGE.			.\" DAMAGE.
	.\"			.\"
	.\" $FreeBSD$			.\" $FreeBSD$
	.Dd August 07, 2013			.Dd November 11, 2021
	.Dt VM_PAGE_BUSY 9			.Dt VM_PAGE_BUSY 9
	.Os			.Os
	.Sh NAME			.Sh NAME
	.Nm vm_page_busied ,			.Nm vm_page_busied ,
	.Nm vm_page_busy_downgrade ,			.Nm vm_page_busy_downgrade ,
	.Nm vm_page_busy_sleep ,			.Nm vm_page_busy_sleep ,
	.Nm vm_page_sbusied ,			.Nm vm_page_sbusied ,
	.Nm vm_page_sbusy ,			.Nm vm_page_sbusy ,
	.Nm vm_page_sleep_if_busy ,
	.Nm vm_page_sunbusy ,			.Nm vm_page_sunbusy ,
	.Nm vm_page_trysbusy ,			.Nm vm_page_trysbusy ,
	.Nm vm_page_tryxbusy ,			.Nm vm_page_tryxbusy ,
	.Nm vm_page_xbusied ,			.Nm vm_page_xbusied ,
	.Nm vm_page_xbusy ,			.Nm vm_page_xbusy ,
	.Nm vm_page_xunbusy ,			.Nm vm_page_xunbusy ,
	.Nm vm_page_assert_sbusied ,			.Nm vm_page_assert_sbusied ,
	.Nm vm_page_assert_unbusied ,			.Nm vm_page_assert_unbusied ,
	.Nm vm_page_assert_xbusied			.Nm vm_page_assert_xbusied
	.Nd protect page identity changes and page content references			.Nd protect page identity changes and page content references
	.Sh SYNOPSIS			.Sh SYNOPSIS
	.In sys/param.h			.In sys/param.h
	.In vm/vm.h			.In vm/vm.h
	.In vm/vm_page.h			.In vm/vm_page.h
	.Ft int			.Ft int
	.Fn vm_page_busied "vm_page_t m"			.Fn vm_page_busied "vm_page_t m"
	.Ft void			.Ft void
	.Fn vm_page_busy_downgrade "vm_page_t m"			.Fn vm_page_busy_downgrade "vm_page_t m"
	.Ft void			.Ft bool
	.Fn vm_page_busy_sleep "vm_page_t m" "const char *msg"			.Fn vm_page_busy_sleep "vm_page_t m" "const char *msg" "int allocflags"
	.Ft int			.Ft int
	.Fn vm_page_sbusied "vm_page_t m"			.Fn vm_page_sbusied "vm_page_t m"
	.Ft void			.Ft void
	.Fn vm_page_sbusy "vm_page_t m"			.Fn vm_page_sbusy "vm_page_t m"
	.Ft int
	.Fn vm_page_sleep_if_busy "vm_page_t m" "const char *msg"
	.Ft void			.Ft void
	.Fn vm_page_sunbusy "vm_page_t m"			.Fn vm_page_sunbusy "vm_page_t m"
	.Ft int			.Ft int
	.Fn vm_page_trysbusy "vm_page_t m"			.Fn vm_page_trysbusy "vm_page_t m"
	.Ft int			.Ft int
	.Fn vm_page_tryxbusy "vm_page_t m"			.Fn vm_page_tryxbusy "vm_page_t m"
	.Ft int			.Ft int
	.Fn vm_page_xbusied "vm_page_t m"			.Fn vm_page_xbusied "vm_page_t m"
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	The			The
	.Fn vm_page_busy_downgrade			.Fn vm_page_busy_downgrade
	function must be used to downgrade			function must be used to downgrade
	.Fa m			.Fa m
	from an exclusive busy state to a shared busy state.			from an exclusive busy state to a shared busy state.
	.Pp			.Pp
	The			The
	.Fn vm_page_busy_sleep			.Fn vm_page_busy_sleep
	function puts the invoking thread to sleep using the appropriate			checks the busy state of the page
	waitchannels for the busy mechanism.			.Fa m
				and puts the invoking thread to sleep if the page is busy.
				The VM object for the page must be locked.
				The
				.Fa allocflags
				parameter must be either
				.Dv 0 ,
				in which case the function will sleep if the page is busied,
				pauamma_gundo.comUnsubmitted Not Done Inline Actions "busied" pauamma_gundo.com: "busied"
				or
				.Dv VM_ALLOC_IGN_SBUSY ,
				in which case the function will sleep only if the page is exclusively
				busied.
				pauamma_gundo.comUnsubmitted Not Done Inline Actions Same as above for "exclusively busied" pauamma_gundo.com: Same as above for "exclusively busied"
				A return value of true indicates that the invoking thread was put to
				sleep and that the object was unlocked.
				A return value of false indicates that the invoking thread did not sleep
				and the object remains locked.
	The parameter			The parameter
	.Fa msg			.Fa msg
	is a string describing the sleep condition for userland tools.			is a string describing the sleep condition for userland tools.
	.Pp			.Pp
	The			The
	.Fn vm_page_busied			.Fn vm_page_busied
	function returns non-zero if the current thread busied			function returns non-zero if the current thread busied
				pauamma_gundo.comUnsubmitted Not Done Inline Actions "busied" again, so I assume it wasn't a mistake above. pauamma_gundo.com: "busied" again, so I assume it wasn't a mistake above.
	.Fa m			.Fa m
	in shared mode.			in shared mode.
	Returns zero otherwise.			Returns zero otherwise.
	.Pp			.Pp
	The			The
	.Fn vm_page_sbusy			.Fn vm_page_sbusy
	function shared busies			function shared busies
	.Fa m .			.Fa m .
	.Pp
	The
	.Fn vm_page_sleep_if_busy
	function puts the invoking thread to sleep, using the appropriate
	waitchannels for the busy mechanism, if
	.Fa m .
	is busied in either exclusive or shared mode.
	If the invoking thread slept a non-zero value is returned, otherwise
	0 is returned.
	The parameter
	.Fa msg
	is a string describing the sleep condition for userland tools.
	.Pp			.Pp
	The			The
	.Fn vm_page_sunbusy			.Fn vm_page_sunbusy
	function shared unbusies			function shared unbusies
				pauamma_gundo.comUnsubmitted Not Done Inline Actions "unbusies" pauamma_gundo.com: "unbusies"
	.Fa m .			.Fa m .
	.Pp			.Pp
	The			The
	.Fn vm_page_trysbusy			.Fn vm_page_trysbusy
	attempts to shared busy			attempts to shared busy
	.Fa m .			.Fa m .
	If the operation cannot immediately succeed			If the operation cannot immediately succeed
	.Fn vm_page_trysbusy			.Fn vm_page_trysbusy
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