Eric Lee / smarc-ti-linux-kernel

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Commit e756bc5670d0f801ca43dc55b8eacde42a5b818b

Authored by Bjorn Helgaas
Committed by Greg Kroah-Hartman
1 parent bfc5c17337
Exists in master and in 16 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

kobject: fix kset sample error path 

Previously, example_init() leaked a kset if any of the object creations
failed.  This fixes the leak by calling kset_unregister() in the error
path.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 1 additions and 0 deletions Inline Diff

samples/kobject/kset-example.c
Diff comments   View file @ e756bc5
1 /* 1 /*
2 * Sample kset and ktype implementation 2 * Sample kset and ktype implementation
3 * 3 *
4 * Copyright (C) 2004-2007 Greg Kroah-Hartman <greg@kroah.com> 4 * Copyright (C) 2004-2007 Greg Kroah-Hartman <greg@kroah.com>
5 * Copyright (C) 2007 Novell Inc. 5 * Copyright (C) 2007 Novell Inc.
6 * 6 *
7 * Released under the GPL version 2 only. 7 * Released under the GPL version 2 only.
8 * 8 *
9 */ 9 */
10 #include <linux/kobject.h> 10 #include <linux/kobject.h>
11 #include <linux/string.h> 11 #include <linux/string.h>
12 #include <linux/sysfs.h> 12 #include <linux/sysfs.h>
13 #include <linux/slab.h> 13 #include <linux/slab.h>
14 #include <linux/module.h> 14 #include <linux/module.h>
15 #include <linux/init.h> 15 #include <linux/init.h>
16 16
17 /* 17 /*
18 * This module shows how to create a kset in sysfs called 18 * This module shows how to create a kset in sysfs called
19 * /sys/kernel/kset-example 19 * /sys/kernel/kset-example
20 * Then tree kobjects are created and assigned to this kset, "foo", "baz", 20 * Then tree kobjects are created and assigned to this kset, "foo", "baz",
21 * and "bar". In those kobjects, attributes of the same name are also 21 * and "bar". In those kobjects, attributes of the same name are also
22 * created and if an integer is written to these files, it can be later 22 * created and if an integer is written to these files, it can be later
23 * read out of it. 23 * read out of it.
24 */ 24 */
25 25
26 26
27 /* 27 /*
28 * This is our "object" that we will create a few of and register them with 28 * This is our "object" that we will create a few of and register them with
29 * sysfs. 29 * sysfs.
30 */ 30 */
31 struct foo_obj { 31 struct foo_obj {
32 struct kobject kobj; 32 struct kobject kobj;
33 int foo; 33 int foo;
34 int baz; 34 int baz;
35 int bar; 35 int bar;
36 }; 36 };
37 #define to_foo_obj(x) container_of(x, struct foo_obj, kobj) 37 #define to_foo_obj(x) container_of(x, struct foo_obj, kobj)
38 38
39 /* a custom attribute that works just for a struct foo_obj. */ 39 /* a custom attribute that works just for a struct foo_obj. */
40 struct foo_attribute { 40 struct foo_attribute {
41 struct attribute attr; 41 struct attribute attr;
42 ssize_t (*show)(struct foo_obj *foo, struct foo_attribute *attr, char *buf); 42 ssize_t (*show)(struct foo_obj *foo, struct foo_attribute *attr, char *buf);
43 ssize_t (*store)(struct foo_obj *foo, struct foo_attribute *attr, const char *buf, size_t count); 43 ssize_t (*store)(struct foo_obj *foo, struct foo_attribute *attr, const char *buf, size_t count);
44 }; 44 };
45 #define to_foo_attr(x) container_of(x, struct foo_attribute, attr) 45 #define to_foo_attr(x) container_of(x, struct foo_attribute, attr)
46 46
47 /* 47 /*
48 * The default show function that must be passed to sysfs. This will be 48 * The default show function that must be passed to sysfs. This will be
49 * called by sysfs for whenever a show function is called by the user on a 49 * called by sysfs for whenever a show function is called by the user on a
50 * sysfs file associated with the kobjects we have registered. We need to 50 * sysfs file associated with the kobjects we have registered. We need to
51 * transpose back from a "default" kobject to our custom struct foo_obj and 51 * transpose back from a "default" kobject to our custom struct foo_obj and
52 * then call the show function for that specific object. 52 * then call the show function for that specific object.
53 */ 53 */
54 static ssize_t foo_attr_show(struct kobject *kobj, 54 static ssize_t foo_attr_show(struct kobject *kobj,
55 struct attribute *attr, 55 struct attribute *attr,
56 char *buf) 56 char *buf)
57 { 57 {
58 struct foo_attribute *attribute; 58 struct foo_attribute *attribute;
59 struct foo_obj *foo; 59 struct foo_obj *foo;
60 60
61 attribute = to_foo_attr(attr); 61 attribute = to_foo_attr(attr);
62 foo = to_foo_obj(kobj); 62 foo = to_foo_obj(kobj);
63 63
64 if (!attribute->show) 64 if (!attribute->show)
65 return -EIO; 65 return -EIO;
66 66
67 return attribute->show(foo, attribute, buf); 67 return attribute->show(foo, attribute, buf);
68 } 68 }
69 69
70 /* 70 /*
71 * Just like the default show function above, but this one is for when the 71 * Just like the default show function above, but this one is for when the
72 * sysfs "store" is requested (when a value is written to a file.) 72 * sysfs "store" is requested (when a value is written to a file.)
73 */ 73 */
74 static ssize_t foo_attr_store(struct kobject *kobj, 74 static ssize_t foo_attr_store(struct kobject *kobj,
75 struct attribute *attr, 75 struct attribute *attr,
76 const char *buf, size_t len) 76 const char *buf, size_t len)
77 { 77 {
78 struct foo_attribute *attribute; 78 struct foo_attribute *attribute;
79 struct foo_obj *foo; 79 struct foo_obj *foo;
80 80
81 attribute = to_foo_attr(attr); 81 attribute = to_foo_attr(attr);
82 foo = to_foo_obj(kobj); 82 foo = to_foo_obj(kobj);
83 83
84 if (!attribute->store) 84 if (!attribute->store)
85 return -EIO; 85 return -EIO;
86 86
87 return attribute->store(foo, attribute, buf, len); 87 return attribute->store(foo, attribute, buf, len);
88 } 88 }
89 89
90 /* Our custom sysfs_ops that we will associate with our ktype later on */ 90 /* Our custom sysfs_ops that we will associate with our ktype later on */
91 static const struct sysfs_ops foo_sysfs_ops = { 91 static const struct sysfs_ops foo_sysfs_ops = {
92 .show = foo_attr_show, 92 .show = foo_attr_show,
93 .store = foo_attr_store, 93 .store = foo_attr_store,
94 }; 94 };
95 95
96 /* 96 /*
97 * The release function for our object. This is REQUIRED by the kernel to 97 * The release function for our object. This is REQUIRED by the kernel to
98 * have. We free the memory held in our object here. 98 * have. We free the memory held in our object here.
99 * 99 *
100 * NEVER try to get away with just a "blank" release function to try to be 100 * NEVER try to get away with just a "blank" release function to try to be
101 * smarter than the kernel. Turns out, no one ever is... 101 * smarter than the kernel. Turns out, no one ever is...
102 */ 102 */
103 static void foo_release(struct kobject *kobj) 103 static void foo_release(struct kobject *kobj)
104 { 104 {
105 struct foo_obj *foo; 105 struct foo_obj *foo;
106 106
107 foo = to_foo_obj(kobj); 107 foo = to_foo_obj(kobj);
108 kfree(foo); 108 kfree(foo);
109 } 109 }
110 110
111 /* 111 /*
112 * The "foo" file where the .foo variable is read from and written to. 112 * The "foo" file where the .foo variable is read from and written to.
113 */ 113 */
114 static ssize_t foo_show(struct foo_obj *foo_obj, struct foo_attribute *attr, 114 static ssize_t foo_show(struct foo_obj *foo_obj, struct foo_attribute *attr,
115 char *buf) 115 char *buf)
116 { 116 {
117 return sprintf(buf, "%d\n", foo_obj->foo); 117 return sprintf(buf, "%d\n", foo_obj->foo);
118 } 118 }
119 119
120 static ssize_t foo_store(struct foo_obj *foo_obj, struct foo_attribute *attr, 120 static ssize_t foo_store(struct foo_obj *foo_obj, struct foo_attribute *attr,
121 const char *buf, size_t count) 121 const char *buf, size_t count)
122 { 122 {
123 sscanf(buf, "%du", &foo_obj->foo); 123 sscanf(buf, "%du", &foo_obj->foo);
124 return count; 124 return count;
125 } 125 }
126 126
127 static struct foo_attribute foo_attribute = 127 static struct foo_attribute foo_attribute =
128 __ATTR(foo, 0666, foo_show, foo_store); 128 __ATTR(foo, 0666, foo_show, foo_store);
129 129
130 /* 130 /*
131 * More complex function where we determine which variable is being accessed by 131 * More complex function where we determine which variable is being accessed by
132 * looking at the attribute for the "baz" and "bar" files. 132 * looking at the attribute for the "baz" and "bar" files.
133 */ 133 */
134 static ssize_t b_show(struct foo_obj *foo_obj, struct foo_attribute *attr, 134 static ssize_t b_show(struct foo_obj *foo_obj, struct foo_attribute *attr,
135 char *buf) 135 char *buf)
136 { 136 {
137 int var; 137 int var;
138 138
139 if (strcmp(attr->attr.name, "baz") == 0) 139 if (strcmp(attr->attr.name, "baz") == 0)
140 var = foo_obj->baz; 140 var = foo_obj->baz;
141 else 141 else
142 var = foo_obj->bar; 142 var = foo_obj->bar;
143 return sprintf(buf, "%d\n", var); 143 return sprintf(buf, "%d\n", var);
144 } 144 }
145 145
146 static ssize_t b_store(struct foo_obj *foo_obj, struct foo_attribute *attr, 146 static ssize_t b_store(struct foo_obj *foo_obj, struct foo_attribute *attr,
147 const char *buf, size_t count) 147 const char *buf, size_t count)
148 { 148 {
149 int var; 149 int var;
150 150
151 sscanf(buf, "%du", &var); 151 sscanf(buf, "%du", &var);
152 if (strcmp(attr->attr.name, "baz") == 0) 152 if (strcmp(attr->attr.name, "baz") == 0)
153 foo_obj->baz = var; 153 foo_obj->baz = var;
154 else 154 else
155 foo_obj->bar = var; 155 foo_obj->bar = var;
156 return count; 156 return count;
157 } 157 }
158 158
159 static struct foo_attribute baz_attribute = 159 static struct foo_attribute baz_attribute =
160 __ATTR(baz, 0666, b_show, b_store); 160 __ATTR(baz, 0666, b_show, b_store);
161 static struct foo_attribute bar_attribute = 161 static struct foo_attribute bar_attribute =
162 __ATTR(bar, 0666, b_show, b_store); 162 __ATTR(bar, 0666, b_show, b_store);
163 163
164 /* 164 /*
165 * Create a group of attributes so that we can create and destroy them all 165 * Create a group of attributes so that we can create and destroy them all
166 * at once. 166 * at once.
167 */ 167 */
168 static struct attribute *foo_default_attrs[] = { 168 static struct attribute *foo_default_attrs[] = {
169 &foo_attribute.attr, 169 &foo_attribute.attr,
170 &baz_attribute.attr, 170 &baz_attribute.attr,
171 &bar_attribute.attr, 171 &bar_attribute.attr,
172 NULL, /* need to NULL terminate the list of attributes */ 172 NULL, /* need to NULL terminate the list of attributes */
173 }; 173 };
174 174
175 /* 175 /*
176 * Our own ktype for our kobjects. Here we specify our sysfs ops, the 176 * Our own ktype for our kobjects. Here we specify our sysfs ops, the
177 * release function, and the set of default attributes we want created 177 * release function, and the set of default attributes we want created
178 * whenever a kobject of this type is registered with the kernel. 178 * whenever a kobject of this type is registered with the kernel.
179 */ 179 */
180 static struct kobj_type foo_ktype = { 180 static struct kobj_type foo_ktype = {
181 .sysfs_ops = &foo_sysfs_ops, 181 .sysfs_ops = &foo_sysfs_ops,
182 .release = foo_release, 182 .release = foo_release,
183 .default_attrs = foo_default_attrs, 183 .default_attrs = foo_default_attrs,
184 }; 184 };
185 185
186 static struct kset *example_kset; 186 static struct kset *example_kset;
187 static struct foo_obj *foo_obj; 187 static struct foo_obj *foo_obj;
188 static struct foo_obj *bar_obj; 188 static struct foo_obj *bar_obj;
189 static struct foo_obj *baz_obj; 189 static struct foo_obj *baz_obj;
190 190
191 static struct foo_obj *create_foo_obj(const char *name) 191 static struct foo_obj *create_foo_obj(const char *name)
192 { 192 {
193 struct foo_obj *foo; 193 struct foo_obj *foo;
194 int retval; 194 int retval;
195 195
196 /* allocate the memory for the whole object */ 196 /* allocate the memory for the whole object */
197 foo = kzalloc(sizeof(*foo), GFP_KERNEL); 197 foo = kzalloc(sizeof(*foo), GFP_KERNEL);
198 if (!foo) 198 if (!foo)
199 return NULL; 199 return NULL;
200 200
201 /* 201 /*
202 * As we have a kset for this kobject, we need to set it before calling 202 * As we have a kset for this kobject, we need to set it before calling
203 * the kobject core. 203 * the kobject core.
204 */ 204 */
205 foo->kobj.kset = example_kset; 205 foo->kobj.kset = example_kset;
206 206
207 /* 207 /*
208 * Initialize and add the kobject to the kernel. All the default files 208 * Initialize and add the kobject to the kernel. All the default files
209 * will be created here. As we have already specified a kset for this 209 * will be created here. As we have already specified a kset for this
210 * kobject, we don't have to set a parent for the kobject, the kobject 210 * kobject, we don't have to set a parent for the kobject, the kobject
211 * will be placed beneath that kset automatically. 211 * will be placed beneath that kset automatically.
212 */ 212 */
213 retval = kobject_init_and_add(&foo->kobj, &foo_ktype, NULL, "%s", name); 213 retval = kobject_init_and_add(&foo->kobj, &foo_ktype, NULL, "%s", name);
214 if (retval) { 214 if (retval) {
215 kobject_put(&foo->kobj); 215 kobject_put(&foo->kobj);
216 return NULL; 216 return NULL;
217 } 217 }
218 218
219 /* 219 /*
220 * We are always responsible for sending the uevent that the kobject 220 * We are always responsible for sending the uevent that the kobject
221 * was added to the system. 221 * was added to the system.
222 */ 222 */
223 kobject_uevent(&foo->kobj, KOBJ_ADD); 223 kobject_uevent(&foo->kobj, KOBJ_ADD);
224 224
225 return foo; 225 return foo;
226 } 226 }
227 227
228 static void destroy_foo_obj(struct foo_obj *foo) 228 static void destroy_foo_obj(struct foo_obj *foo)
229 { 229 {
230 kobject_put(&foo->kobj); 230 kobject_put(&foo->kobj);
231 } 231 }
232 232
233 static int __init example_init(void) 233 static int __init example_init(void)
234 { 234 {
235 /* 235 /*
236 * Create a kset with the name of "kset_example", 236 * Create a kset with the name of "kset_example",
237 * located under /sys/kernel/ 237 * located under /sys/kernel/
238 */ 238 */
239 example_kset = kset_create_and_add("kset_example", NULL, kernel_kobj); 239 example_kset = kset_create_and_add("kset_example", NULL, kernel_kobj);
240 if (!example_kset) 240 if (!example_kset)
241 return -ENOMEM; 241 return -ENOMEM;
242 242
243 /* 243 /*
244 * Create three objects and register them with our kset 244 * Create three objects and register them with our kset
245 */ 245 */
246 foo_obj = create_foo_obj("foo"); 246 foo_obj = create_foo_obj("foo");
247 if (!foo_obj) 247 if (!foo_obj)
248 goto foo_error; 248 goto foo_error;
249 249
250 bar_obj = create_foo_obj("bar"); 250 bar_obj = create_foo_obj("bar");
251 if (!bar_obj) 251 if (!bar_obj)
252 goto bar_error; 252 goto bar_error;
253 253
254 baz_obj = create_foo_obj("baz"); 254 baz_obj = create_foo_obj("baz");
255 if (!baz_obj) 255 if (!baz_obj)
256 goto baz_error; 256 goto baz_error;
257 257
258 return 0; 258 return 0;
259 259
260 baz_error: 260 baz_error:
261 destroy_foo_obj(bar_obj); 261 destroy_foo_obj(bar_obj);
262 bar_error: 262 bar_error:
263 destroy_foo_obj(foo_obj); 263 destroy_foo_obj(foo_obj);
264 foo_error: 264 foo_error:
265 kset_unregister(example_kset);
265 return -EINVAL; 266 return -EINVAL;
266 } 267 }
267 268
268 static void __exit example_exit(void) 269 static void __exit example_exit(void)
269 { 270 {
270 destroy_foo_obj(baz_obj); 271 destroy_foo_obj(baz_obj);
271 destroy_foo_obj(bar_obj); 272 destroy_foo_obj(bar_obj);
272 destroy_foo_obj(foo_obj); 273 destroy_foo_obj(foo_obj);
273 kset_unregister(example_kset); 274 kset_unregister(example_kset);
274 } 275 }
275 276
276 module_init(example_init); 277 module_init(example_init);
277 module_exit(example_exit); 278 module_exit(example_exit);
278 MODULE_LICENSE("GPL"); 279 MODULE_LICENSE("GPL");
279 MODULE_AUTHOR("Greg Kroah-Hartman <greg@kroah.com>"); 280 MODULE_AUTHOR("Greg Kroah-Hartman <greg@kroah.com>");
280 281