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
|
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 25 Jan 2017 16:34:27 +0100
Subject: [PATCH 088/351] radix-tree: use local locks
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=005680192f8aae72026cff0eff54af2ae3cb0b49
The preload functionality uses per-CPU variables and preempt-disable to
ensure that it does not switch CPUs during its usage. This patch adds
local_locks() instead preempt_disable() for the same purpose and to
remain preemptible on -RT.
Cc: stable-rt@vger.kernel.org
Reported-and-debugged-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/idr.h | 5 +----
include/linux/radix-tree.h | 7 ++-----
lib/radix-tree.c | 32 +++++++++++++++++++++++---------
3 files changed, 26 insertions(+), 18 deletions(-)
diff --git a/include/linux/idr.h b/include/linux/idr.h
index b6c6151c7446..81c9df5c04fa 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -169,10 +169,7 @@ static inline bool idr_is_empty(const struct idr *idr)
* Each idr_preload() should be matched with an invocation of this
* function. See idr_preload() for details.
*/
-static inline void idr_preload_end(void)
-{
- preempt_enable();
-}
+void idr_preload_end(void);
/**
* idr_for_each_entry() - Iterate over an IDR's elements of a given type.
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 34149e8b5f73..affb0fc4c5b6 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -330,6 +330,8 @@ unsigned int radix_tree_gang_lookup_slot(const struct radix_tree_root *,
int radix_tree_preload(gfp_t gfp_mask);
int radix_tree_maybe_preload(gfp_t gfp_mask);
int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order);
+void radix_tree_preload_end(void);
+
void radix_tree_init(void);
void *radix_tree_tag_set(struct radix_tree_root *,
unsigned long index, unsigned int tag);
@@ -349,11 +351,6 @@ unsigned int radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *,
unsigned int max_items, unsigned int tag);
int radix_tree_tagged(const struct radix_tree_root *, unsigned int tag);
-static inline void radix_tree_preload_end(void)
-{
- preempt_enable();
-}
-
int radix_tree_split_preload(unsigned old_order, unsigned new_order, gfp_t);
int radix_tree_split(struct radix_tree_root *, unsigned long index,
unsigned new_order);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index e5cab5c4e383..9309e813bc1f 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -38,7 +38,7 @@
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/string.h>
-
+#include <linux/locallock.h>
/* Number of nodes in fully populated tree of given height */
static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly;
@@ -87,6 +87,7 @@ struct radix_tree_preload {
struct radix_tree_node *nodes;
};
static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
+static DEFINE_LOCAL_IRQ_LOCK(radix_tree_preloads_lock);
static inline struct radix_tree_node *entry_to_node(void *ptr)
{
@@ -405,12 +406,13 @@ radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent,
* succeed in getting a node here (and never reach
* kmem_cache_alloc)
*/
- rtp = this_cpu_ptr(&radix_tree_preloads);
+ rtp = &get_locked_var(radix_tree_preloads_lock, radix_tree_preloads);
if (rtp->nr) {
ret = rtp->nodes;
rtp->nodes = ret->parent;
rtp->nr--;
}
+ put_locked_var(radix_tree_preloads_lock, radix_tree_preloads);
/*
* Update the allocation stack trace as this is more useful
* for debugging.
@@ -476,14 +478,14 @@ static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)
*/
gfp_mask &= ~__GFP_ACCOUNT;
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
rtp = this_cpu_ptr(&radix_tree_preloads);
while (rtp->nr < nr) {
- preempt_enable();
+ local_unlock(radix_tree_preloads_lock);
node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
if (node == NULL)
goto out;
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
rtp = this_cpu_ptr(&radix_tree_preloads);
if (rtp->nr < nr) {
node->parent = rtp->nodes;
@@ -525,7 +527,7 @@ int radix_tree_maybe_preload(gfp_t gfp_mask)
if (gfpflags_allow_blocking(gfp_mask))
return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
/* Preloading doesn't help anything with this gfp mask, skip it */
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
return 0;
}
EXPORT_SYMBOL(radix_tree_maybe_preload);
@@ -563,7 +565,7 @@ int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
/* Preloading doesn't help anything with this gfp mask, skip it */
if (!gfpflags_allow_blocking(gfp_mask)) {
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
return 0;
}
@@ -597,6 +599,12 @@ int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
return __radix_tree_preload(gfp_mask, nr_nodes);
}
+void radix_tree_preload_end(void)
+{
+ local_unlock(radix_tree_preloads_lock);
+}
+EXPORT_SYMBOL(radix_tree_preload_end);
+
static unsigned radix_tree_load_root(const struct radix_tree_root *root,
struct radix_tree_node **nodep, unsigned long *maxindex)
{
@@ -2102,10 +2110,16 @@ EXPORT_SYMBOL(radix_tree_tagged);
void idr_preload(gfp_t gfp_mask)
{
if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE))
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
}
EXPORT_SYMBOL(idr_preload);
+void idr_preload_end(void)
+{
+ local_unlock(radix_tree_preloads_lock);
+}
+EXPORT_SYMBOL(idr_preload_end);
+
int ida_pre_get(struct ida *ida, gfp_t gfp)
{
/*
@@ -2114,7 +2128,7 @@ int ida_pre_get(struct ida *ida, gfp_t gfp)
* to return to the ida_pre_get() step.
*/
if (!__radix_tree_preload(gfp, IDA_PRELOAD_SIZE))
- preempt_enable();
+ local_unlock(radix_tree_preloads_lock);
if (!this_cpu_read(ida_bitmap)) {
struct ida_bitmap *bitmap = kzalloc(sizeof(*bitmap), gfp);
|
