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Diffstat (limited to 'hurd/hurd/port.h')
| -rw-r--r-- | hurd/hurd/port.h | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/hurd/hurd/port.h b/hurd/hurd/port.h new file mode 100644 index 0000000000..a057503d4a --- /dev/null +++ b/hurd/hurd/port.h @@ -0,0 +1,152 @@ +/* Lightweight user references for ports. +Copyright (C) 1993, 1994 Free Software Foundation, Inc. +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library 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 +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +#ifndef _HURD_PORT_H + +#define _HURD_PORT_H 1 +#include <features.h> + +#include <mach.h> +#include <hurd/userlink.h> +#include <spin-lock.h> +#include <hurd/signal.h> + + +/* Structure describing a cell containing a port. With the lock held, a + user extracts PORT, and attaches his own link (in local storage) to the + USERS chain. PORT can then safely be used. When PORT is no longer + needed, with the lock held, the user removes his link from the chain. + If his link is the last, and PORT has changed since he fetched it, the + user deallocates the port he used. See <hurd/userlink.h>. */ + +struct hurd_port + { + spin_lock_t lock; /* Locks rest. */ + struct hurd_userlink *users; /* Chain of users; see below. */ + mach_port_t port; /* Port. */ + }; + + +/* Evaluate EXPR with the variable `port' bound to the port in PORTCELL. */ + +#define HURD_PORT_USE(portcell, expr) \ + ({ struct hurd_port *const __p = (portcell); \ + struct hurd_userlink __link; \ + const mach_port_t port = _hurd_port_get (__p, &__link); \ + __typeof(expr) __result = (expr); \ + _hurd_port_free (__p, &__link, port); \ + __result; }) + + +#ifndef _EXTERN_INLINE +#define _EXTERN_INLINE extern __inline +#endif + + +/* Initialize *PORT to INIT. */ + +_EXTERN_INLINE void +_hurd_port_init (struct hurd_port *port, mach_port_t init) +{ + __spin_lock_init (&port->lock); + port->users = NULL; + port->port = init; +} + + +/* Get a reference to *PORT, which is locked. + Pass return value and LINK to _hurd_port_free when done. */ + +_EXTERN_INLINE mach_port_t +_hurd_port_locked_get (struct hurd_port *port, + struct hurd_userlink *link) +{ + mach_port_t result; + result = port->port; + if (result != MACH_PORT_NULL) + _hurd_userlink_link (&port->users, link); + __spin_unlock (&port->lock); + return result; +} + +/* Same, but locks PORT first. */ + +_EXTERN_INLINE mach_port_t +_hurd_port_get (struct hurd_port *port, + struct hurd_userlink *link) +{ + mach_port_t result; + HURD_CRITICAL_BEGIN; + __spin_lock (&port->lock); + result = _hurd_port_locked_get (port, link); + HURD_CRITICAL_END; + return result; +} + + +/* Free a reference gotten with `USED_PORT = _hurd_port_get (PORT, LINK);' */ + +_EXTERN_INLINE void +_hurd_port_free (struct hurd_port *port, + struct hurd_userlink *link, + mach_port_t used_port) +{ + int dealloc; + if (used_port == MACH_PORT_NULL) + /* When we fetch an empty port cell with _hurd_port_get, + it does not link us on the users chain, since there is + no shared resource. */ + return; + HURD_CRITICAL_BEGIN; + __spin_lock (&port->lock); + dealloc = _hurd_userlink_unlink (link); + __spin_unlock (&port->lock); + HURD_CRITICAL_END; + if (dealloc) + __mach_port_deallocate (__mach_task_self (), used_port); +} + + +/* Set *PORT's port to NEWPORT. NEWPORT's reference is consumed by PORT->port. + PORT->lock is locked. */ + +_EXTERN_INLINE void +_hurd_port_locked_set (struct hurd_port *port, mach_port_t newport) +{ + mach_port_t old; + old = _hurd_userlink_clear (&port->users) ? port->port : MACH_PORT_NULL; + port->port = newport; + __spin_unlock (&port->lock); + if (old != MACH_PORT_NULL) + __mach_port_deallocate (__mach_task_self (), old); +} + +/* Same, but locks PORT first. */ + +_EXTERN_INLINE void +_hurd_port_set (struct hurd_port *port, mach_port_t newport) +{ + HURD_CRITICAL_BEGIN; + __spin_lock (&port->lock); + _hurd_port_locked_set (port, newport); + HURD_CRITICAL_END; +} + + +#endif /* hurd/port.h */ |