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diff --git a/share/man/man9/g_event.9 b/share/man/man9/g_event.9 new file mode 100644 index 000000000000..380caa82a0b8 --- /dev/null +++ b/share/man/man9/g_event.9 @@ -0,0 +1,189 @@ +.\" +.\" Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org> +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES +.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. +.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, +.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 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 DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd January 16, 2004 +.Dt G_EVENT 9 +.Os +.Sh NAME +.Nm g_post_event , +.Nm g_waitfor_event , +.Nm g_cancel_event +.Nd "GEOM events management" +.Sh SYNOPSIS +.In geom/geom.h +.Ft int +.Fn g_post_event "g_event_t *func" "void *arg" "int flag" ... +.Ft int +.Fn g_waitfor_event "g_event_t *func" "void *arg" "int flag" ... +.Ft void +.Fn g_cancel_event "void *ref" +.Sh DESCRIPTION +The GEOM framework has its own event queue to inform classes about important +events. +The event queue can be also used by GEOM classes themselves, for example +to work around some restrictions in the I/O path, where sleeping, heavy weight +tasks, etc.\& are not permitted. +.Pp +The +.Fn g_post_event +function tells the GEOM framework to call function +.Fa func +with argument +.Fa arg +from the event queue. +The +.Fa flag +argument is passed to +.Xr malloc 9 +for memory allocations inside of +.Fn g_post_event . +The only allowed flags are +.Dv M_WAITOK +and +.Dv M_NOWAIT . +The rest of the arguments are used as references to identify the event. +An event can be canceled by using any of the given references as an +argument to +.Fn g_cancel_event . +The list of references has to end with a +.Dv NULL +value. +.Pp +The +.Fn g_waitfor_event +function is a blocking version of the +.Fn g_post_event +function. +It waits until the event is finished or canceled and then returns. +.Pp +The +.Fn g_cancel_event +function cancels all event(s) identified by +.Fa ref . +Cancellation is equivalent to calling the requested function +with requested arguments and argument +.Fa flag +set to +.Dv EV_CANCEL . +.Sh RESTRICTIONS/CONDITIONS +.Fn g_post_event : +.Bl -item -offset indent +.It +The argument +.Fa flag +has to be +.Dv M_WAITOK +or +.Dv M_NOWAIT . +.It +The list of references has to end with a +.Dv NULL +value. +.El +.Pp +.Fn g_waitfor_event : +.Bl -item -offset indent +.It +The argument +.Fa flag +has to be +.Dv M_WAITOK +or +.Dv M_NOWAIT . +.It +The list of references has to end with a +.Dv NULL +value. +.It +The +.Fn g_waitfor_event +function cannot be called from an event, since doing so would result +in a deadlock. +.El +.Sh RETURN VALUES +The +.Fn g_post_event +and +.Fn g_waitfor_event +functions +return 0 if successful; otherwise an error code is returned. +.Sh EXAMPLES +Example of a function called from the event queue. +.Bd -literal -offset indent +void +example_event(void *arg, int flag) +{ + + if (flag == EV_CANCEL) { + printf("Event with argument %p canceled.\\n", arg); + return; + } + + printf("Event with argument %p called.\\n", arg); +} +.Ed +.Sh ERRORS +Possible errors for the +.Fn g_post_event +function: +.Bl -tag -width Er +.It Bq Er ENOMEM +The +.Fa flag +argument was set to +.Dv M_NOWAIT +and there was insufficient memory. +.El +.Pp +Possible errors for the +.Fn g_waitfor_event +function: +.Bl -tag -width Er +.It Bq Er EAGAIN +The event was canceled. +.It Bq Er ENOMEM +The +.Fa flag +argument was set to +.Dv M_NOWAIT +and there was insufficient memory. +.El +.Sh SEE ALSO +.Xr geom 4 , +.Xr DECLARE_GEOM_CLASS 9 , +.Xr g_access 9 , +.Xr g_attach 9 , +.Xr g_bio 9 , +.Xr g_consumer 9 , +.Xr g_data 9 , +.Xr g_geom 9 , +.Xr g_provider 9 , +.Xr g_provider_by_name 9 , +.Xr g_wither_geom 9 +.Sh AUTHORS +.An -nosplit +This manual page was written by +.An Pawel Jakub Dawidek Aq pjd@FreeBSD.org . |