drivers/base/devcoredump.c

   1 /*
   2  * This file is provided under the GPLv2 license.
   3  *
   4  * GPL LICENSE SUMMARY
   5  *
   6  * Copyright(c) 2014 Intel Mobile Communications GmbH
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of version 2 of the GNU General Public License as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * The full GNU General Public License is included in this distribution
  18  * in the file called COPYING.
  19  *
  20  * Contact Information:
  21  *  Intel Linux Wireless <ilw@linux.intel.com>
  22  * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
  23  *
  24  * Author: Johannes Berg <johannes@sipsolutions.net>
  25  */
  26 #include <linux/module.h>
  27 #include <linux/device.h>
  28 #include <linux/devcoredump.h>
  29 #include <linux/list.h>
  30 #include <linux/slab.h>
  31 #include <linux/fs.h>
  32 #include <linux/workqueue.h>
  33
  34 /* if data isn't read by userspace after 5 minutes then delete it */
  35 #define DEVCD_TIMEOUT   (HZ * 60 * 5)
  36
  37 struct devcd_entry {
  38         struct device devcd_dev;
  39         const void *data;
  40         size_t datalen;
  41         struct module *owner;
  42         ssize_t (*read)(char *buffer, loff_t offset, size_t count,
  43                         const void *data, size_t datalen);
  44         void (*free)(const void *data);
  45         struct delayed_work del_wk;
  46         struct device *failing_dev;
  47 };
  48
  49 static struct devcd_entry *dev_to_devcd(struct device *dev)
  50 {
  51         return container_of(dev, struct devcd_entry, devcd_dev);
  52 }
  53
  54 static void devcd_dev_release(struct device *dev)
  55 {
  56         struct devcd_entry *devcd = dev_to_devcd(dev);
  57
  58         devcd->free(devcd->data);
  59         module_put(devcd->owner);
  60
  61         /*
  62          * this seems racy, but I don't see a notifier or such on
  63          * a struct device to know when it goes away?
  64          */
  65         if (devcd->failing_dev->kobj.sd)
  66                 sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
  67                                   "devcoredump");
  68
  69         put_device(devcd->failing_dev);
  70         kfree(devcd);
  71 }
  72
  73 static void devcd_del(struct work_struct *wk)
  74 {
  75         struct devcd_entry *devcd;
  76
  77         devcd = container_of(wk, struct devcd_entry, del_wk.work);
  78
  79         device_del(&devcd->devcd_dev);
  80         put_device(&devcd->devcd_dev);
  81 }
  82
  83 static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj,
  84                                struct bin_attribute *bin_attr,
  85                                char *buffer, loff_t offset, size_t count)
  86 {
  87         struct device *dev = kobj_to_dev(kobj);
  88         struct devcd_entry *devcd = dev_to_devcd(dev);
  89
  90         return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
  91 }
  92
  93 static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
  94                                 struct bin_attribute *bin_attr,
  95                                 char *buffer, loff_t offset, size_t count)
  96 {
  97         struct device *dev = kobj_to_dev(kobj);
  98         struct devcd_entry *devcd = dev_to_devcd(dev);
  99
 100         mod_delayed_work(system_wq, &devcd->del_wk, 0);
 101
 102         return count;
 103 }
 104
 105 static struct bin_attribute devcd_attr_data = {
 106         .attr = { .name = "data", .mode = S_IRUSR | S_IWUSR, },
 107         .size = 0,
 108         .read = devcd_data_read,
 109         .write = devcd_data_write,
 110 };
 111
 112 static struct bin_attribute *devcd_dev_bin_attrs[] = {
 113         &devcd_attr_data, NULL,
 114 };
 115
 116 static const struct attribute_group devcd_dev_group = {
 117         .bin_attrs = devcd_dev_bin_attrs,
 118 };
 119
 120 static const struct attribute_group *devcd_dev_groups[] = {
 121         &devcd_dev_group, NULL,
 122 };
 123
 124 static struct class devcd_class = {
 125         .name           = "devcoredump",
 126         .owner          = THIS_MODULE,
 127         .dev_release    = devcd_dev_release,
 128         .dev_groups     = devcd_dev_groups,
 129 };
 130
 131 static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
 132                            const void *data, size_t datalen)
 133 {
 134         if (offset > datalen)
 135                 return -EINVAL;
 136
 137         if (offset + count > datalen)
 138                 count = datalen - offset;
 139
 140         if (count)
 141                 memcpy(buffer, ((u8 *)data) + offset, count);
 142
 143         return count;
 144 }
 145
 146 /**
 147  * dev_coredumpv - create device coredump with vmalloc data
 148  * @dev: the struct device for the crashed device
 149  * @data: vmalloc data containing the device coredump
 150  * @datalen: length of the data
 151  * @gfp: allocation flags
 152  *
 153  * This function takes ownership of the vmalloc'ed data and will free
 154  * it when it is no longer used. See dev_coredumpm() for more information.
 155  */
 156 void dev_coredumpv(struct device *dev, const void *data, size_t datalen,
 157                    gfp_t gfp)
 158 {
 159         dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, vfree);
 160 }
 161 EXPORT_SYMBOL_GPL(dev_coredumpv);
 162
 163 static int devcd_match_failing(struct device *dev, const void *failing)
 164 {
 165         struct devcd_entry *devcd = dev_to_devcd(dev);
 166
 167         return devcd->failing_dev == failing;
 168 }
 169
 170 /**
 171  * dev_coredumpm - create device coredump with read/free methods
 172  * @dev: the struct device for the crashed device
 173  * @owner: the module that contains the read/free functions, use %THIS_MODULE
 174  * @data: data cookie for the @read/@free functions
 175  * @datalen: length of the data
 176  * @gfp: allocation flags
 177  * @read: function to read from the given buffer
 178  * @free: function to free the given buffer
 179  *
 180  * Creates a new device coredump for the given device. If a previous one hasn't
 181  * been read yet, the new coredump is discarded. The data lifetime is determined
 182  * by the device coredump framework and when it is no longer needed the @free
 183  * function will be called to free the data.
 184  */
 185 void dev_coredumpm(struct device *dev, struct module *owner,
 186                    const void *data, size_t datalen, gfp_t gfp,
 187                    ssize_t (*read)(char *buffer, loff_t offset, size_t count,
 188                                    const void *data, size_t datalen),
 189                    void (*free)(const void *data))
 190 {
 191         static atomic_t devcd_count = ATOMIC_INIT(0);
 192         struct devcd_entry *devcd;
 193         struct device *existing;
 194
 195         existing = class_find_device(&devcd_class, NULL, dev,
 196                                      devcd_match_failing);
 197         if (existing) {
 198                 put_device(existing);
 199                 goto free;
 200         }
 201
 202         if (!try_module_get(owner))
 203                 goto free;
 204
 205         devcd = kzalloc(sizeof(*devcd), gfp);
 206         if (!devcd)
 207                 goto put_module;
 208
 209         devcd->owner = owner;
 210         devcd->data = data;
 211         devcd->datalen = datalen;
 212         devcd->read = read;
 213         devcd->free = free;
 214         devcd->failing_dev = get_device(dev);
 215
 216         device_initialize(&devcd->devcd_dev);
 217
 218         dev_set_name(&devcd->devcd_dev, "devcd%d",
 219                      atomic_inc_return(&devcd_count));
 220         devcd->devcd_dev.class = &devcd_class;
 221
 222         if (device_add(&devcd->devcd_dev))
 223                 goto put_device;
 224
 225         if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
 226                               "failing_device"))
 227                 /* nothing - symlink will be missing */;
 228
 229         if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
 230                               "devcoredump"))
 231                 /* nothing - symlink will be missing */;
 232
 233         INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
 234         schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
 235
 236         return;
 237  put_device:
 238         put_device(&devcd->devcd_dev);
 239  put_module:
 240         module_put(owner);
 241  free:
 242         free(data);
 243 }
 244 EXPORT_SYMBOL_GPL(dev_coredumpm);
 245
 246 static int __init devcoredump_init(void)
 247 {
 248         return class_register(&devcd_class);
 249 }
 250 __initcall(devcoredump_init);
 251
 252 static int devcd_free(struct device *dev, void *data)
 253 {
 254         struct devcd_entry *devcd = dev_to_devcd(dev);
 255
 256         flush_delayed_work(&devcd->del_wk);
 257         return 0;
 258 }
 259
 260 static void __exit devcoredump_exit(void)
 261 {
 262         class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
 263         class_unregister(&devcd_class);
 264 }
 265 __exitcall(devcoredump_exit);