From 99be20e0687fff63642da6f753f56427b0ba4efc Mon Sep 17 00:00:00 2001 From: "Michael I. Bushnell" Date: Fri, 3 Dec 1993 01:55:28 +0000 Subject: Initial revision --- libiohelp/get_conch.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 libiohelp/get_conch.c (limited to 'libiohelp') diff --git a/libiohelp/get_conch.c b/libiohelp/get_conch.c new file mode 100644 index 00000000..4e2467b6 --- /dev/null +++ b/libiohelp/get_conch.c @@ -0,0 +1,58 @@ +/* + Copyright (C) 1993 Free Software Foundation + + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2, or (at + your option) any later version. + + This program is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ + +#include + +/* The conch must be locked when calling this routine. */ +error_t +_libioserver_internal_get_conch (struct conch *c) +{ + struct shared *user_sh; + int error = 0; + + again: + user_sh = c->holder_shared_page; + + if (user_sh) + { + spin_lock (&user_sh->lock); + switch (user_sh->conch_status) + { + case USER_HAS_CONCH: + user_sh->conch_status = USER_RELEASE_CONCH; + /* fall through ... */ + case USER_RELEASE_CONCH: + spin_unlock (&user_sh->lock); + condition_wait (&c->wait, &c->lock); + /* Anything can have happened */ + goto again; + + case USER_COULD_HAVE_CONCH: + user_sh->conch_status = USER_HAS_NOT_CONCH; + spin_unlock (&user_sh->lock); + error = fetch_shared_data (c->holder); + break; + + case USER_HAS_NOT_CONCH: + spin_unlock (&user_sh->lock); + break; + } + } + c->holder = 0; + c->holder_shared_page = 0; + return error; +} -- cgit v1.2.3