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
219
220
221
222
223
224
225
226
|
From 80adc8fb1dabebcc9d41cb6c0f122860061c12a3 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 23 Nov 2016 16:29:32 +0100
Subject: [PATCH 169/347] locking/percpu-rwsem: Remove preempt_disable variants
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
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(-)
diff --git a/fs/locks.c b/fs/locks.c
index 28270e74be34..552476d6f6bb 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -936,7 +936,7 @@ static int flock_lock_inode(struct inode *inode, struct file_lock *request)
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;
@@ -977,7 +977,7 @@ static int flock_lock_inode(struct inode *inode, struct file_lock *request)
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);
@@ -1015,7 +1015,7 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request,
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
@@ -1187,7 +1187,7 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request,
}
out:
spin_unlock(&ctx->flc_lock);
- percpu_up_read_preempt_enable(&file_rwsem);
+ percpu_up_read(&file_rwsem);
/*
* Free any unused locks.
*/
@@ -1462,7 +1462,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
return error;
}
- percpu_down_read_preempt_disable(&file_rwsem);
+ percpu_down_read(&file_rwsem);
spin_lock(&ctx->flc_lock);
time_out_leases(inode, &dispose);
@@ -1514,13 +1514,13 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
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);
@@ -1537,7 +1537,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
}
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);
}
@@ -1693,7 +1693,7 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
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);
@@ -1764,7 +1764,7 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
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);
@@ -1787,7 +1787,7 @@ static int generic_delete_lease(struct file *filp, void *owner)
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 &&
@@ -1800,7 +1800,7 @@ static int generic_delete_lease(struct file *filp, void *owner)
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;
}
@@ -2531,13 +2531,13 @@ locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
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);
}
diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
index 79b99d653e03..fb44e237316d 100644
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -29,7 +29,7 @@ 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();
@@ -47,16 +47,10 @@ static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore *
__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();
}
@@ -83,13 +77,9 @@ static inline int percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
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().
*/
@@ -102,12 +92,6 @@ static inline void percpu_up_read_preempt_enable(struct percpu_rw_semaphore *sem
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 *);
--
2.36.1
|
