dlm: replace schedule with cond_resched
[linux-3.10.git] / fs / dlm / ast.c
1 /******************************************************************************
2 *******************************************************************************
3 **
4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
5 **  Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
6 **
7 **  This copyrighted material is made available to anyone wishing to use,
8 **  modify, copy, or redistribute it subject to the terms and conditions
9 **  of the GNU General Public License v.2.
10 **
11 *******************************************************************************
12 ******************************************************************************/
13
14 #include "dlm_internal.h"
15 #include "lock.h"
16 #include "user.h"
17 #include "ast.h"
18
19 #define WAKE_ASTS  0
20
21 static struct list_head         ast_queue;
22 static spinlock_t               ast_queue_lock;
23 static struct task_struct *     astd_task;
24 static unsigned long            astd_wakeflags;
25 static struct mutex             astd_running;
26
27
28 void dlm_del_ast(struct dlm_lkb *lkb)
29 {
30         spin_lock(&ast_queue_lock);
31         if (lkb->lkb_ast_type & (AST_COMP | AST_BAST))
32                 list_del(&lkb->lkb_astqueue);
33         spin_unlock(&ast_queue_lock);
34 }
35
36 void dlm_add_ast(struct dlm_lkb *lkb, int type)
37 {
38         if (lkb->lkb_flags & DLM_IFL_USER) {
39                 dlm_user_add_ast(lkb, type);
40                 return;
41         }
42
43         spin_lock(&ast_queue_lock);
44         if (!(lkb->lkb_ast_type & (AST_COMP | AST_BAST))) {
45                 kref_get(&lkb->lkb_ref);
46                 list_add_tail(&lkb->lkb_astqueue, &ast_queue);
47         }
48         lkb->lkb_ast_type |= type;
49         spin_unlock(&ast_queue_lock);
50
51         set_bit(WAKE_ASTS, &astd_wakeflags);
52         wake_up_process(astd_task);
53 }
54
55 static void process_asts(void)
56 {
57         struct dlm_ls *ls = NULL;
58         struct dlm_rsb *r = NULL;
59         struct dlm_lkb *lkb;
60         void (*cast) (void *astparam);
61         void (*bast) (void *astparam, int mode);
62         int type = 0, found, bmode;
63
64         for (;;) {
65                 found = 0;
66                 spin_lock(&ast_queue_lock);
67                 list_for_each_entry(lkb, &ast_queue, lkb_astqueue) {
68                         r = lkb->lkb_resource;
69                         ls = r->res_ls;
70
71                         if (dlm_locking_stopped(ls))
72                                 continue;
73
74                         list_del(&lkb->lkb_astqueue);
75                         type = lkb->lkb_ast_type;
76                         lkb->lkb_ast_type = 0;
77                         found = 1;
78                         break;
79                 }
80                 spin_unlock(&ast_queue_lock);
81
82                 if (!found)
83                         break;
84
85                 cast = lkb->lkb_astfn;
86                 bast = lkb->lkb_bastfn;
87                 bmode = lkb->lkb_bastmode;
88
89                 if ((type & AST_COMP) && cast)
90                         cast(lkb->lkb_astparam);
91
92                 /* FIXME: Is it safe to look at lkb_grmode here
93                    without doing a lock_rsb() ?
94                    Look at other checks in v1 to avoid basts. */
95
96                 if ((type & AST_BAST) && bast)
97                         if (!dlm_modes_compat(lkb->lkb_grmode, bmode))
98                                 bast(lkb->lkb_astparam, bmode);
99
100                 /* this removes the reference added by dlm_add_ast
101                    and may result in the lkb being freed */
102                 dlm_put_lkb(lkb);
103
104                 cond_resched();
105         }
106 }
107
108 static inline int no_asts(void)
109 {
110         int ret;
111
112         spin_lock(&ast_queue_lock);
113         ret = list_empty(&ast_queue);
114         spin_unlock(&ast_queue_lock);
115         return ret;
116 }
117
118 static int dlm_astd(void *data)
119 {
120         while (!kthread_should_stop()) {
121                 set_current_state(TASK_INTERRUPTIBLE);
122                 if (!test_bit(WAKE_ASTS, &astd_wakeflags))
123                         schedule();
124                 set_current_state(TASK_RUNNING);
125
126                 mutex_lock(&astd_running);
127                 if (test_and_clear_bit(WAKE_ASTS, &astd_wakeflags))
128                         process_asts();
129                 mutex_unlock(&astd_running);
130         }
131         return 0;
132 }
133
134 void dlm_astd_wake(void)
135 {
136         if (!no_asts()) {
137                 set_bit(WAKE_ASTS, &astd_wakeflags);
138                 wake_up_process(astd_task);
139         }
140 }
141
142 int dlm_astd_start(void)
143 {
144         struct task_struct *p;
145         int error = 0;
146
147         INIT_LIST_HEAD(&ast_queue);
148         spin_lock_init(&ast_queue_lock);
149         mutex_init(&astd_running);
150
151         p = kthread_run(dlm_astd, NULL, "dlm_astd");
152         if (IS_ERR(p))
153                 error = PTR_ERR(p);
154         else
155                 astd_task = p;
156         return error;
157 }
158
159 void dlm_astd_stop(void)
160 {
161         kthread_stop(astd_task);
162 }
163
164 void dlm_astd_suspend(void)
165 {
166         mutex_lock(&astd_running);
167 }
168
169 void dlm_astd_resume(void)
170 {
171         mutex_unlock(&astd_running);
172 }
173