debuggers.hg

view xen/common/stop_machine.c @ 0:7d21f7218375

Exact replica of unstable on 051908 + README-this
author Mukesh Rathor
date Mon May 19 15:34:57 2008 -0700 (2008-05-19)
parents
children 5c0bf00e371d
line source
1 /******************************************************************************
2 * common/stop_machine.c
3 *
4 * Facilities to put whole machine in a safe 'stop' state
5 *
6 * Copyright 2005 Rusty Russell rusty@rustcorp.com.au IBM Corporation
7 * Copyright 2008 Kevin Tian <kevin.tian@intel.com>, Intel Corporation.
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms and conditions of the GNU General Public License,
11 * version 2, as published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope it will be useful, but WITHOUT
14 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
16 * more details.
17 *
18 * You should have received a copy of the GNU General Public License along with
19 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
20 * Place - Suite 330, Boston, MA 02111-1307 USA.
21 */
23 #include <xen/config.h>
24 #include <xen/init.h>
25 #include <xen/sched.h>
26 #include <xen/spinlock.h>
27 #include <xen/softirq.h>
28 #include <xen/errno.h>
29 #include <xen/smp.h>
30 #include <asm/current.h>
31 #include <asm/processor.h>
33 enum stopmachine_state {
34 STOPMACHINE_START,
35 STOPMACHINE_PREPARE,
36 STOPMACHINE_DISABLE_IRQ,
37 STOPMACHINE_INVOKE,
38 STOPMACHINE_EXIT
39 };
41 struct stopmachine_data {
42 unsigned int nr_cpus;
44 enum stopmachine_state state;
45 atomic_t done;
47 unsigned int fn_cpu;
48 int fn_result;
49 int (*fn)(void *);
50 void *fn_data;
51 };
53 static struct stopmachine_data stopmachine_data;
54 static DEFINE_SPINLOCK(stopmachine_lock);
56 static void stopmachine_set_state(enum stopmachine_state state)
57 {
58 atomic_set(&stopmachine_data.done, 0);
59 smp_wmb();
60 stopmachine_data.state = state;
61 while ( atomic_read(&stopmachine_data.done) != stopmachine_data.nr_cpus )
62 cpu_relax();
63 }
65 int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
66 {
67 cpumask_t allbutself;
68 unsigned int i, nr_cpus;
69 int ret;
71 BUG_ON(!local_irq_is_enabled());
73 allbutself = cpu_online_map;
74 cpu_clear(smp_processor_id(), allbutself);
75 nr_cpus = cpus_weight(allbutself);
77 if ( nr_cpus == 0 )
78 {
79 BUG_ON(cpu != smp_processor_id());
80 return (*fn)(data);
81 }
83 /* Note: We shouldn't spin on lock when it's held by others since others
84 * is expecting this cpus to enter softirq context. Or else deadlock
85 * is caused.
86 */
87 if ( !spin_trylock(&stopmachine_lock) )
88 return -EBUSY;
90 stopmachine_data.fn = fn;
91 stopmachine_data.fn_data = data;
92 stopmachine_data.nr_cpus = nr_cpus;
93 stopmachine_data.fn_cpu = cpu;
94 atomic_set(&stopmachine_data.done, 0);
95 stopmachine_data.state = STOPMACHINE_START;
97 smp_wmb();
99 for_each_cpu_mask ( i, allbutself )
100 cpu_raise_softirq(i, STOPMACHINE_SOFTIRQ);
102 stopmachine_set_state(STOPMACHINE_PREPARE);
104 local_irq_disable();
105 stopmachine_set_state(STOPMACHINE_DISABLE_IRQ);
107 if ( cpu == smp_processor_id() )
108 stopmachine_data.fn_result = (*fn)(data);
109 stopmachine_set_state(STOPMACHINE_INVOKE);
110 ret = stopmachine_data.fn_result;
112 stopmachine_set_state(STOPMACHINE_EXIT);
113 local_irq_enable();
115 spin_unlock(&stopmachine_lock);
117 return ret;
118 }
120 static void stopmachine_softirq(void)
121 {
122 enum stopmachine_state state = STOPMACHINE_START;
124 smp_mb();
126 while ( state != STOPMACHINE_EXIT )
127 {
128 while ( stopmachine_data.state == state )
129 cpu_relax();
131 state = stopmachine_data.state;
132 switch ( state )
133 {
134 case STOPMACHINE_DISABLE_IRQ:
135 local_irq_disable();
136 break;
137 case STOPMACHINE_INVOKE:
138 if ( stopmachine_data.fn_cpu == smp_processor_id() )
139 stopmachine_data.fn_result =
140 stopmachine_data.fn(stopmachine_data.fn_data);
141 break;
142 default:
143 break;
144 }
146 smp_mb();
147 atomic_inc(&stopmachine_data.done);
148 }
150 local_irq_enable();
151 }
153 static int __init cpu_stopmachine_init(void)
154 {
155 open_softirq(STOPMACHINE_SOFTIRQ, stopmachine_softirq);
156 return 0;
157 }
158 __initcall(cpu_stopmachine_init);