1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
|
Subject: locking/percpu-rwsem: Remove preempt_disable variants
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed Nov 23 16:29:32 CET 2016
Effective revert commit:
87709e28dc7c ("fs/locks: Use percpu_down_read_preempt_disable()")
This is causing major pain for PREEMPT_RT and is only a very small
performance issue for PREEMPT=y.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
---
fs/locks.c | 32 ++++++++++++++++----------------
include/linux/percpu-rwsem.h | 24 ++++--------------------
2 files changed, 20 insertions(+), 36 deletions(-)
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -935,7 +935,7 @@ static int flock_lock_inode(struct inode
return -ENOMEM;
}
- percpu_down_read_preempt_disable(&file_rwsem);
+ percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
if (request->fl_flags & FL_ACCESS)
goto find_conflict;
@@ -976,7 +976,7 @@ static int flock_lock_inode(struct inode
out:
spin_unlock(&ctx->flc_lock);
- percpu_up_read_preempt_enable(&file_rwsem);
+ percpu_up_read(&file_rwsem);
if (new_fl)
locks_free_lock(new_fl);
locks_dispose_list(&dispose);
@@ -1013,7 +1013,7 @@ static int posix_lock_inode(struct inode
new_fl2 = locks_alloc_lock();
}
- percpu_down_read_preempt_disable(&file_rwsem);
+ percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
/*
* New lock request. Walk all POSIX locks and look for conflicts. If
@@ -1185,7 +1185,7 @@ static int posix_lock_inode(struct inode
}
out:
spin_unlock(&ctx->flc_lock);
- percpu_up_read_preempt_enable(&file_rwsem);
+ percpu_up_read(&file_rwsem);
/*
* Free any unused locks.
*/
@@ -1460,7 +1460,7 @@ int __break_lease(struct inode *inode, u
return error;
}
- percpu_down_read_preempt_disable(&file_rwsem);
+ percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
time_out_leases(inode, &dispose);
@@ -1512,13 +1512,13 @@ int __break_lease(struct inode *inode, u
locks_insert_block(fl, new_fl);
trace_break_lease_block(inode, new_fl);
spin_unlock(&ctx->flc_lock);
- percpu_up_read_preempt_enable(&file_rwsem);
+ percpu_up_read(&file_rwsem);
locks_dispose_list(&dispose);
error = wait_event_interruptible_timeout(new_fl->fl_wait,
!new_fl->fl_next, break_time);
- percpu_down_read_preempt_disable(&file_rwsem);
+ percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
trace_break_lease_unblock(inode, new_fl);
locks_delete_block(new_fl);
@@ -1535,7 +1535,7 @@ int __break_lease(struct inode *inode, u
}
out:
spin_unlock(&ctx->flc_lock);
- percpu_up_read_preempt_enable(&file_rwsem);
+ percpu_up_read(&file_rwsem);
locks_dispose_list(&dispose);
locks_free_lock(new_fl);
return error;
@@ -1609,7 +1609,7 @@ int fcntl_getlease(struct file *filp)
ctx = smp_load_acquire(&inode->i_flctx);
if (ctx && !list_empty_careful(&ctx->flc_lease)) {
- percpu_down_read_preempt_disable(&file_rwsem);
+ percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
time_out_leases(inode, &dispose);
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
@@ -1619,7 +1619,7 @@ int fcntl_getlease(struct file *filp)
break;
}
spin_unlock(&ctx->flc_lock);
- percpu_up_read_preempt_enable(&file_rwsem);
+ percpu_up_read(&file_rwsem);
locks_dispose_list(&dispose);
}
@@ -1694,7 +1694,7 @@ generic_add_lease(struct file *filp, lon
return -EINVAL;
}
- percpu_down_read_preempt_disable(&file_rwsem);
+ percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
time_out_leases(inode, &dispose);
error = check_conflicting_open(dentry, arg, lease->fl_flags);
@@ -1765,7 +1765,7 @@ generic_add_lease(struct file *filp, lon
lease->fl_lmops->lm_setup(lease, priv);
out:
spin_unlock(&ctx->flc_lock);
- percpu_up_read_preempt_enable(&file_rwsem);
+ percpu_up_read(&file_rwsem);
locks_dispose_list(&dispose);
if (is_deleg)
inode_unlock(inode);
@@ -1788,7 +1788,7 @@ static int generic_delete_lease(struct f
return error;
}
- percpu_down_read_preempt_disable(&file_rwsem);
+ percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
if (fl->fl_file == filp &&
@@ -1801,7 +1801,7 @@ static int generic_delete_lease(struct f
if (victim)
error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
spin_unlock(&ctx->flc_lock);
- percpu_up_read_preempt_enable(&file_rwsem);
+ percpu_up_read(&file_rwsem);
locks_dispose_list(&dispose);
return error;
}
@@ -2532,13 +2532,13 @@ locks_remove_lease(struct file *filp, st
if (list_empty(&ctx->flc_lease))
return;
- percpu_down_read_preempt_disable(&file_rwsem);
+ percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
if (filp == fl->fl_file)
lease_modify(fl, F_UNLCK, &dispose);
spin_unlock(&ctx->flc_lock);
- percpu_up_read_preempt_enable(&file_rwsem);
+ percpu_up_read(&file_rwsem);
locks_dispose_list(&dispose);
}
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -28,7 +28,7 @@ static struct percpu_rw_semaphore name =
extern int __percpu_down_read(struct percpu_rw_semaphore *, int);
extern void __percpu_up_read(struct percpu_rw_semaphore *);
-static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore *sem)
+static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
{
might_sleep();
@@ -46,16 +46,10 @@ static inline void percpu_down_read_pree
__this_cpu_inc(*sem->read_count);
if (unlikely(!rcu_sync_is_idle(&sem->rss)))
__percpu_down_read(sem, false); /* Unconditional memory barrier */
- barrier();
/*
- * The barrier() prevents the compiler from
+ * The preempt_enable() prevents the compiler from
* bleeding the critical section out.
*/
-}
-
-static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
-{
- percpu_down_read_preempt_disable(sem);
preempt_enable();
}
@@ -82,13 +76,9 @@ static inline int percpu_down_read_trylo
return ret;
}
-static inline void percpu_up_read_preempt_enable(struct percpu_rw_semaphore *sem)
+static inline void percpu_up_read(struct percpu_rw_semaphore *sem)
{
- /*
- * The barrier() prevents the compiler from
- * bleeding the critical section out.
- */
- barrier();
+ preempt_disable();
/*
* Same as in percpu_down_read().
*/
@@ -101,12 +91,6 @@ static inline void percpu_up_read_preemp
rwsem_release(&sem->rw_sem.dep_map, 1, _RET_IP_);
}
-static inline void percpu_up_read(struct percpu_rw_semaphore *sem)
-{
- preempt_disable();
- percpu_up_read_preempt_enable(sem);
-}
-
extern void percpu_down_write(struct percpu_rw_semaphore *);
extern void percpu_up_write(struct percpu_rw_semaphore *);
|
