{"id":1393,"date":"2010-09-21T15:40:46","date_gmt":"2010-09-21T07:40:46","guid":{"rendered":"http:\/\/edsionte.com\/techblog\/?p=1393"},"modified":"2014-01-24T09:48:32","modified_gmt":"2014-01-24T01:48:32","slug":"char_dev-c%e6%ba%90%e7%a0%81%e5%88%86%e6%9e%90","status":"publish","type":"post","link":"http:\/\/edsionte.com\/techblog\/archives\/1393","title":{"rendered":"register_chrdev_region\u51fd\u6570\u6e90\u7801\u5206\u6790"},"content":{"rendered":"

\u5982\u4f55\u627e\u5230\u4e00\u4e2a\u6709\u6548\u7684\u5207\u5165\u70b9\u53bb\u6df1\u5165\u5206\u6790\u5185\u6838\u6e90\u7801\uff0c\u8fd9\u662f\u4e00\u4e2a\u4ee4\u4eba\u6df1\u601d\u7684\u95ee\u9898\u3002\u672c\u6587\u4ee5\u524d\u6587<\/a>\u4e2d\u672a\u8be6\u7ec6\u8bf4\u660e\u7684\u51fd\u6570\u4e3a\u5207\u5165\u70b9\uff0c\u6df1\u5165\u5206\u6790char_dev.c\u6587\u4ef6\u7684\u4ee3\u7801\u3002\u5982\u679c\u4f60\u5df2\u7ecf\u62e5\u6709\u4e86C\u8bed\u8a00\u57fa\u7840\u548c\u4e00\u4e9b\u6570\u636e\u7ed3\u6784\u57fa\u7840\uff0c\u90a3\u4e48\u8fd8\u7b49\u4ec0\u4e48\uff1fLet’s go\uff01<\/p>\n

\u5728\u300a\u5b57\u7b26\u8bbe\u5907\u9a71\u52a8\u5206\u6790\u300b\u4e00\u6587\u4e2d\uff0c\u6211\u4eec\u8bf4\u5230register_chrdev_region\u51fd\u6570\u7684\u529f\u80fd\u662f\u5728\u5df2\u77e5\u8d77\u59cb\u8bbe\u5907\u53f7\u7684\u60c5\u51b5\u4e0b\u53bb\u7533\u8bf7\u4e00\u7ec4\u8fde\u7eed\u7684\u8bbe\u5907\u53f7\u3002\u4e0d\u8fc7\u5927\u90e8\u5206\u9a71\u52a8\u4e66\u7c4d\u90fd\u6ca1\u6709\u53bb\u6df1\u5165\u8bf4\u660e\u6b64\u51fd\u6570\uff0c\u53ef\u80fd\u662f\u56e0\u4e3a\u8fd9\u4e2a\u51fd\u6570\u5185\u90e8\u5c01\u88c5\u4e86__register_chrdev_region(unsigned int major, unsigned int baseminor, int minorct, const char *name)\u51fd\u6570\u7684\u539f\u56e0\u3002\u4e0d\u8fc7\u6211\u4eec\u4e0d\u7528\u82e6\u607c\uff0c\u8fd9\u6b63\u597d\u4fc3\u4f7f\u6211\u4eec\u53bb\u5206\u6790\u8fd9\u4e2a\u51fd\u6570\u3002<\/p>\n

194int register_chrdev_region(dev_t from, unsigned count, const char *name)\r\n 195{\r\n 196        struct char_device_struct *cd;\r\n 197        dev_t to = from + count;\r\n 198        dev_t n, next;\r\n 199\r\n 200        for (n = from; n <\\ to; n = next) {\r\n 201                next = MKDEV(MAJOR(n)+1, 0);\r\n 202                if (next >\\ to)\r\n 203                        next = to;\r\n 204                cd = __register_chrdev_region(MAJOR(n), MINOR(n),\r\n 205                               next - n, name);\r\n 206                if (IS_ERR(cd))\r\n 207                        goto fail;\r\n 208        }\r\n 209        return 0;\r\n 210fail:\r\n 211        to = n;\r\n 212        for (n = from; n <\\ to; n = next) {\r\n 213                next = MKDEV(MAJOR(n)+1, 0);\r\n 214                kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));\r\n 215        }\r\n 216        return PTR_ERR(cd);\r\n 217}<\/pre>\n
\u9996\u5148\u503c\u5f97\u6211\u4eec\u6ce8\u610f\u7684\u662f\uff0c\u8fd9\u4e2a\u51fd\u6570\u6bcf\u6b21\u5206\u914d\u7684\u662f\u4e00\u7ec4\u8bbe\u5907\u7f16\u53f7\u3002\u5176\u4e2dfrom\u53c2\u6570\u662f\u8fd9\u7ec4\u8fde\u7eed\u8bbe\u5907\u53f7\u7684\u8d77\u59cb\u8bbe\u5907\u53f7\uff0ccount\u662f\u8fd9\u7ec4\u8bbe\u5907\u53f7\u7684\u5927\u5c0f\uff08\u4e5f\u662f\u6b21\u8bbe\u5907\u53f7\u7684\u4e2a\u6570\uff09\uff0cname\u53c2\u6570\u5904\u7406\u672c\u7ec4\u8bbe\u5907\u7684\u9a71\u52a8\u540d\u79f0\u3002\u53e6\u5916\uff0c\u5f53\u6b21\u8bbe\u5907\u53f7\u6570\u76ee\u8fc7\u591a\uff08count\u8fc7\u591a\uff09\u7684\u65f6\u5019\uff0c\u6b21\u8bbe\u5907\u53f7\u53ef\u80fd\u4f1a\u6ea2\u51fa\u5230\u4e0b\u4e00\u4e2a\u4e3b\u8bbe\u5907\u3002\u56e0\u6b64\u6211\u4eec\u5728for\u8bed\u53e5\u4e2d\u53ef\u4ee5\u770b\u5230\uff0c\u9996\u5148\u5f97\u5230\u4e0b\u4e00\u4e2a\u4e3b\u8bbe\u5907\u53f7\uff08\u5176\u5b9e\u4e5f\u662f\u4e00\u4e2a\u8bbe\u5907\u53f7\uff0c\u53ea\u4e0d\u8fc7\u6b64\u65f6\u7684\u6b21\u8bbe\u5907\u53f7\u4e3a0\uff09\u5e76\u5b58\u50a8\u4e8enext\u4e2d\u3002\u7136\u540e\u5224\u65ad\u5728from\u7684\u57fa\u7840\u4e0a\u518d\u8ffd\u52a0count\u4e2a\u8bbe\u5907\u662f\u5426\u5df2\u7ecf\u6ea2\u51fa\u5230\u4e0b\u4e00\u4e2a\u4e3b\u8bbe\u5907\u53f7\u3002\u5982\u679c\u6ca1\u6709\u6ea2\u51fa\uff08next\u5c0f\u4e8eto\uff09\uff0c\u90a3\u4e48\u6574\u4e2afor\u8bed\u53e5\u5c31\u53ea\u6267\u884c\u4e2a\u4e00\u6b21__register_chrdev_region\u51fd\u6570\uff1b\u5426\u5219\u5f53\u8bbe\u5907\u53f7\u6ea2\u51fa\u65f6\uff0c\u4f1a\u628a\u5f53\u524d\u6ea2\u51fa\u7684\u8bbe\u5907\u53f7\u8303\u56f4\u5212\u5206\u4e3a\u51e0\u4e2a\u5c0f\u8303\u56f4\uff0c\u5206\u522b\u8c03\u7528__register_chrdev_region\u51fd\u6570\u3002<\/p>\n
\u5982\u679c\u5728\u67d0\u4e2a\u5c0f\u8303\u56f4\u8c03\u7528__register_chrdev_region\u65f6\u51fa\u73b0\u4e86\u5931\u8d25\uff0c\u90a3\u4e48\u4f1a\u5c06\u6b64\u524d\u5206\u914d\u7684\u8bbe\u5907\u53f7\u90fd\u91ca\u653e\u3002<\/p>\n
\u5176\u5b9eregister_chrdev_region\u51fd\u6570\u8fd8\u6ca1\u6709\u5b8c\u5168\u8bf4\u6e05\u9664\u8bbe\u5907\u53f7\u5206\u914d\u7684\u5177\u4f53\u8fc7\u7a0b\uff0c\u56e0\u4e3a\u5177\u4f53\u67d0\u4e2a\u5c0f\u8303\u56f4\u7684\u8bbe\u5907\u53f7\u662f\u7531__register_chrdev_region\u51fd\u6570\u6765\u5b8c\u6210\u7684\u3002\u53ef\u80fd\u4f60\u5df2\u7ecf\u6ce8\u610f\u5230\u5728register_chrdev_region\u51fd\u6570\u6e90\u7801\u4e2d\u51fa\u73b0\u4e86struct char_device_struct\u7ed3\u6784\uff0c\u6211\u4eec\u9996\u5148\u6765\u770b\u8fd9\u4e2a\u7ed3\u6784\u4f53\uff1a<\/p>\n
  50static struct char_device_struct {\r\n  51        struct char_device_struct *next;\r\n  52        unsigned int major;\r\n  53        unsigned int baseminor;\r\n  54        int minorct;\r\n  55        char name[64];\r\n  56        struct cdev *cdev;              \/* will die *\/\r\n  57} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];<\/pre>\n
\u5728register_chrdev_region\u51fd\u6570\u4e2d\uff0c\u5728\u6bcf\u4e2a\u5b57\u7b26\u8bbe\u5907\u53f7\u7684\u5c0f\u8303\u56f4\u4e0a\u8c03\u7528__register_chrdev_region\u51fd\u6570\uff0c\u90fd\u4f1a\u8fd4\u56de\u4e00\u4e2astruct char_device_struct\u7c7b\u578b\u7684\u6307\u9488\u3002\u56e0\u6b64\u6211\u4eec\u53ef\u4ee5\u5f97\u77e5\uff0cstruct char_device_struct\u7c7b\u578b\u5bf9\u5e94\u7684\u5e76\u4e0d\u662f\u6bcf\u4e00\u4e2a\u5b57\u7b26\u8bbe\u5907\uff0c\u800c\u662f\u5177\u6709\u8fde\u7eed\u8bbe\u5907\u53f7\u7684\u4e00\u7ec4\u5b57\u7b26\u8bbe\u5907\u3002\u4ece\u8fd9\u4e2a\u7ed3\u6784\u4f53\u5185\u90e8\u7684\u5b57\u6bb5\u4e5f\u53ef\u4ee5\u770b\u51fa\uff0c\u8fd9\u7ec4\u8fde\u7eed\u7684\u8bbe\u5907\u53f7\u7684\u4e3b\u8bbe\u5907\u53f7\u4e3amajor\uff0c\u6b21\u8bbe\u5907\u53f7\u8d77\u59cb\u4e3abaseminor\uff0c\u6b21\u8bbe\u5907\u53f7\u8303\u56f4\u4e3aminorct\uff0c\u8fd9\u7ec4\u8bbe\u5907\u53f7\u5bf9\u5e94\u7684\u8bbe\u5907\u9a71\u52a8\u540d\u79f0\u4e3aname\uff0ccdev\u4e3a\u6307\u5411\u8fd9\u4e2a\u5b57\u7b26\u8bbe\u5907\u9a71\u52a8\u7684\u6307\u9488\u3002<\/p>\n
\u8fd9\u91cc\u8981\u7279\u522b\u8bf4\u660e\u7684\u662f\uff0c\u5185\u6838\u4e2d\u6240\u6709\u5df2\u5206\u914d\u7684\u5b57\u7b26\u8bbe\u5907\u7f16\u53f7\u90fd\u8bb0\u5f55\u5728\u4e00\u4e2a\u540d\u4e3achrdevs\u6563\u5217\u8868\u91cc\u3002\u8be5\u6563\u5217\u8868\u4e2d\u7684\u6bcf\u4e00\u4e2a\u5143\u7d20\u662f\u4e00\u4e2a char_device_struct\u7ed3\u6784\uff0c\u8fd9\u4e2a\u6563\u5217\u8868\u7684\u5927\u5c0f\u4e3a255\uff08CHRDEV_MAJOR_HASH_SIZE\uff09\uff0c\u8fd9\u662f\u56e0\u4e3a\u7cfb\u7edf\u5c4f\u853d\u4e8612\u4f4d\u4e3b\u8bbe\u5907\u53f7\u7684\u524d\u56db\u4f4d\u3002\u65e2\u7136\u8bf4\u5230\u6563\u5217\u8868\uff0c\u90a3\u4e48\u80af\u5b9a\u4f1a\u51fa\u73b0\u51b2\u7a81\u73b0\u8c61\uff0c\u56e0\u6b64next\u5b57\u6bb5\u5c31\u662f\u51b2\u7a81\u94fe\u8868\u4e2d\u7684\u4e0b\u4e00\u4e2a\u5143\u7d20\u7684\u6307\u9488\u3002<\/p>\n
\u63a5\u4e0b\u6765\u6211\u4eec\u8be6\u7ec6\u6765\u6790__register_chrdev_region\u51fd\u6570\u3002\u9996\u5148\u4e3acd\u53d8\u91cf\u5206\u914d\u5185\u5b58\u5e76\u7528\u96f6\u6765\u586b\u5145\uff08\u8fd9\u5c31\u662f\u7528kzalloc\u800c\u4e0d\u662fkmalloc\u7684\u539f\u56e0\uff09\u3002\u63a5\u7740\u901a\u8fc7P\u64cd\u4f5c\u4f7f\u5f97\u540e\u7eed\u8981\u6267\u884c\u7684\u8bed\u53e5\u5747\u5904\u4e8e\u4e34\u754c\u533a\u3002<\/p>\n
  92static struct char_device_struct *\r\n  93__register_chrdev_region(unsigned int major, unsigned int baseminor,\r\n  94                           int minorct, const char *name)\r\n  95{\r\n  96        struct char_device_struct *cd, **cp;\r\n  97        int ret = 0;\r\n  98        int i;\r\n  99\r\n 100        cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);\r\n 101        if (cd == NULL)\r\n 102                return ERR_PTR(-ENOMEM);\r\n 103\r\n 104        mutex_lock(&chrdevs_lock);<\/pre>\n
\u5982\u679cmajor\u4e3a0\uff0c\u4e5f\u5c31\u662f\u672a\u6307\u5b9a\u4e00\u4e2a\u5177\u4f53\u7684\u4e3b\u8bbe\u5907\u53f7\uff0c\u9700\u8981\u52a8\u6001\u5206\u914d\u3002\u90a3\u4e48\u63a5\u4e0b\u6765\u7684if\u8bed\u53e5\u5c31\u5728\u6574\u4e2a\u6563\u5217\u8868\u4e2d\u4e3a\u8fd9\u7ec4\u8bbe\u5907\u5bfb\u627e\u5408\u9002\u7684\u4f4d\u7f6e\uff0c\u5373\u4ece\u6563\u5217\u8868\u7684\u672b\u5c3e\u5f00\u59cb\u5bfb\u627echrdevs[i]\u4e3a\u7a7a\u7684\u60c5\u51b5\u3002\u82e5\u627e\u5230\u540e\uff0c\u90a3\u4e48i\u4e0d\u4ec5\u4ee3\u8868\u8fd9\u7ec4\u8bbe\u5907\u7684\u4e3b\u8bbe\u5907\u53f7\uff0c\u4e5f\u4ee3\u8868\u5176\u5728\u6563\u5217\u8868\u4e2d\u7684\u5173\u952e\u5b57\u3002\u5f53\u7136\uff0c\u5982\u679c\u4e3b\u8bbe\u5907\u53f7\u5b9e\u73b0\u5df2\u6307\u5b9a\uff0c\u90a3\u4e48\u53ef\u4e0d\u53bb\u7406\u4f1a\u8fd9\u90e8\u5206\u4ee3\u7801\u3002<\/p>\n
 105\r\n 106        \/* temporary *\/\r\n 107        if (major == 0) {\r\n 108                for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {\r\n 109                        if (chrdevs[i] == NULL)\r\n 110                                break;\r\n 111                }\r\n 112\r\n 113                if (i == 0) {\r\n 114                        ret = -EBUSY;\r\n 115                        goto out;\r\n 116                }\r\n 117                major = i;\r\n 118                ret = major;\r\n 119        }<\/pre>\n
\u63a5\u7740\u5bf9\u5c06\u53c2\u6570\u4e2d\u7684\u503c\u4f9d\u6b21\u8d4b\u7ed9cd\u53d8\u91cf\u7684\u5bf9\u5e94\u5b57\u6bb5\u3002\u5f53\u4e3b\u8bbe\u5907\u53f7\u975e\u96f6\uff0c\u5373\u4e8b\u5148\u5df2\u77e5\u7684\u8bdd\uff0c\u90a3\u4e48\u8fd8\u8981\u901a\u8fc7major_to_index\u51fd\u6570\u5bf9\u5176\u8fdb\u884c\u9664\u6a21255\u8fd0\u7b97\uff0c\u56e0\u6b64\u6574\u4e2a\u6563\u5217\u8868\u5173\u952e\u5b57\u7684\u8303\u56f4\u662f0\uff5e254\u3002<\/p>\n
 120\r\n 121        cd->major = major;\r\n 122        cd->baseminor = baseminor;\r\n 123        cd->minorct = minorct;\r\n 124        strlcpy(cd->name, name, sizeof(cd->name));\r\n 125\r\n 126        i = major_to_index(major);<\/pre>\n
\u81f3\u6b64\uff0c\u6211\u4eec\u901a\u8fc7\u4e0a\u9762\u7684\u4ee3\u7801\u4f1a\u5f97\u5230\u4e00\u4e2a\u6709\u6548\u7684\u4e3b\u8bbe\u5907\u53f7\uff08\u5982\u679c\u53ef\u4ee5\u7ee7\u7eed\u6267\u884c\u4e0b\u9762\u4ee3\u7801\u7684\u8bdd\uff09\uff0c\u90a3\u4e48\u63a5\u4e0b\u6765\u8fd8\u4e0d\u80fd\u7ee7\u7eed\u5206\u914d\u3002\u6b63\u5982\u4f60\u6240\u77e5\u7684\u90a3\u6837\uff0c\u6563\u5217\u8868\u4e2d\u7684\u51b2\u7a81\u662f\u5728\u6240\u96be\u514d\u7684\u3002\u56e0\u6b64\u6211\u4eec\u5f97\u5230major\u7684\u503c\u540e\uff0c\u6211\u4eec\u8981\u53bb\u904d\u5386\u51b2\u7a81\u94fe\u8868\uff0c\u4e3a\u5f53\u524d\u6211\u4eec\u6240\u8ff0\u7684char_device_struct\u7c7b\u578b\u7684\u53d8\u91cfcd\u53bb\u5bfb\u627e\u6b63\u786e\u7684\u4f4d\u7f6e\u3002\u66f4\u91cd\u8981\u7684\u662f\uff0c\u6211\u4eec\u8981\u68c0\u67e5\u5f53\u524d\u7684\u6b21\u8bbe\u5907\u53f7\u8303\u56f4\uff0c\u5373baseminor~baseminor+minorct\uff0c\u662f\u5426\u548c\u4e4b\u524d\u7684\u5df2\u5206\u914d\u7684\u6b21\u8bbe\u5907\u53f7\uff08\u524d\u63d0\u662fmajor\u76f8\u540c\uff09\u8303\u56f4\u6709\u91cd\u53e0\u3002<\/p>\n
\u4e0b\u9762\u7684for\u5faa\u73af\u5c31\u662f\u5728\u51b2\u7a81\u94fe\u8868\u4e2d\u67e5\u627e\u4f55\u65f6\u7684\u4f4d\u7f6e\uff0c\u5f53\u51fa\u73b0\u4ee5\u4e0b\u4e09\u79cd\u60c5\u51b5\u65f6\uff0cfor\u8bed\u53e5\u4f1a\u505c\u6b62\u3002<\/p>\n
(1)\u5982\u679c\u51b2\u7a81\u8868\u4e2d\u6b63\u88ab\u904d\u5386\u7684\u7ed3\u70b9\u7684\u4e3b\u8bbe\u5907\u53f7\uff08*(cp)->major\uff09\u5927\u4e8e\u6211\u4eec\u6240\u5206\u914d\u7684\u4e3b\u8bbe\u5907\u53f7(major)\uff0c\u90a3\u4e48\u5c31\u53ef\u4ee5\u8df3\u51fafor\u8bed\u53e5\uff0c\u4e0d\u518d\u7ee7\u7eed\u67e5\u627e\u3002\u6b64\u65f6\u5e94\u8be5\u8bf4\u8bbe\u5907\u53f7\u5206\u914d\u6210\u529f\u4e86\uff0c\u90a3\u4e48cd\u7ed3\u70b9\u53ea\u9700\u7b49\u5f85\u88ab\u63d2\u5230\u51b2\u7a81\u94fe\u8868\u5f53\u4e2d\uff08*cp\u8282\u70b9\u4e4b\u524d\uff09\u3002<\/p>\n
(2)\u5982\u679c(*cp)\u7ed3\u70b9\u548ccd\u7ed3\u70b9\u7684\u4e3b\u8bbe\u5907\u53f7\u76f8\u540c\uff0c\u4f46\u662f\u524d\u8005\u7684\u6b21\u8bbe\u5907\u53f7\u8d77\u70b9\u6bd4cd\u7ed3\u70b9\u7684\u5927\uff0c\u90a3\u4e48\u8df3\u51fafor\u8bed\u53e5\uff0c\u7b49\u5f85\u4e0b\u4e00\u6b65\u7684\u8303\u56f4\u91cd\u53e0\u7684\u68c0\u6d4b\u3002<\/p>\n
(3)\u5982\u679c(*cp)\u7ed3\u70b9\u548ccd\u7ed3\u70b9\u7684\u4e3b\u8bbe\u5907\u53f7\u76f8\u540c\uff0c\u4f46\u662fcd\u7ed3\u70b9\u7684\u6b21\u8bbe\u5907\u53f7\u8d77\u70b9\u5c0f\u4e8e(*cp)\u7ed3\u70b9\u7684\u6b21\u8bbe\u5907\u53f7\u7684\u7ec8\u70b9\uff0c\u90a3\u4e48\u4f1a\u8df3\u51fafor\u8bed\u53e5\u3002\u6b64\u65f6\u5f88\u53ef\u80fd\u4e24\u4e2a\u8303\u56f4\u7684\u6b21\u8bbe\u5907\u53f7\u53d1\u751f\u4e86\u91cd\u53e0\u3002<\/p>\n
\u7531\u4e0a\u9762\u7684\u5206\u6790\u53ef\u4ee5\u770b\u51fa\uff0c\u51b2\u7a81\u8868\u4e2d\u662f\u6309\u7167\u8bbe\u5907\u53f7\u9012\u589e\u7684\u987a\u5e8f\u6392\u5217\u7684\u3002<\/p>\n
 127\r\n 128        for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)\r\n 129                if ((*cp)->major > major ||\r\n 130                    ((*cp)->major == major &&\r\n 131                     (((*cp)->baseminor >= baseminor) ||\r\n 132                      ((*cp)->baseminor + (*cp)->minorct > baseminor))))\r\n 133                        break;<\/pre>\n
\u63a5\u4e0b\u6765\u68c0\u6d4b\u5f53\u4e3b\u8bbe\u5907\u53f7\u76f8\u540c\u65f6\uff0c\u6b21\u8bbe\u5907\u8303\u56f4\u662f\u5426\u53d1\u751f\u4e86\u91cd\u53e0\u3002\u9996\u5148\u4f9d\u6b21\u8ba1\u7b97\u51fa\u65b0\u8001\u6b21\u8bbe\u5907\u53f7\u7684\u8303\u56f4\uff0c\u63a5\u7740\u8fdb\u884c\u8303\u56f4\u5224\u65ad\u3002\u7b2c\u4e00\u4e2a\u5224\u65ad\u8bed\u53e5\u662f\u68c0\u6d4b\u65b0\u8303\u56f4\u7684\u7ec8\u70b9\u662f\u5426\u5728\u8001\u8303\u56f4\u7684\u4e4b\u95f4\uff1b\u7b2c\u4e8c\u4e2a\u5224\u65ad\u8bed\u53e5\u662f\u68c0\u6d4b\u65b0\u8303\u56f4\u7684\u8d77\u70b9\u662f\u5426\u5728\u8001\u8303\u56f4\u4e4b\u95f4\u3002<\/p>\n
 134\r\n 135        \/* Check for overlapping minor ranges.  *\/\r\n 136        if (*cp && (*cp)->major == major) {\r\n 137                int old_min = (*cp)->baseminor;\r\n 138                int old_max = (*cp)->baseminor + (*cp)->minorct - 1;\r\n 139                int new_min = baseminor;\r\n 140                int new_max = baseminor + minorct - 1;\r\n 141\r\n 142                \/* New driver overlaps from the left.  *\/\r\n 143                if (new_max >= old_min && new_max <= old_max) {\r\n 144                        ret = -EBUSY;\r\n 145                        goto out;\r\n 146                }\r\n 147\r\n 148                \/* New driver overlaps from the right.  *\/\r\n 149                if (new_min <= old_max && new_min >= old_min) {\r\n 150                        ret = -EBUSY;\r\n 151                        goto out;\r\n 152                }\r\n 153        }<\/pre>\n
\u5f53\u4e00\u5207\u90fd\u6b63\u5e38\u540e\uff0c\u5c31\u5c06char_device_struct\u63cf\u8ff0\u7b26\u63d2\u5165\u5230\u4e2d\u9014\u94fe\u8868\u4e2d\u3002\u81f3\u6b64\uff0c\u4e00\u6b21\u5c0f\u8303\u56f4\u7684\u8bbe\u5907\u53f7\u5206\u914d\u6210\u529f\u3002\u5e76\u4e14\u6b64\u65f6\u79bb\u5f00\u4e34\u754c\u533a\uff0c\u8fdb\u884cV\u64cd\u4f5c\u3002\u5982\u679c\u4e0a\u8ff0\u8fc7\u7a0b\u4e2d\u6709\u4efb\u4f55\u5931\u8d25\uff0c\u5219\u4f1a\u8df3\u8f6c\u5230out\u5904\uff0c\u8fd4\u56de\u9519\u8bef\u4fe1\u606f\u3002<\/p>\n
 154\r\n 155        cd->next = *cp;\r\n 156        *cp = cd;\r\n 157        mutex_unlock(&chrdevs_lock);\r\n 158        return cd;\r\n 159out:\r\n 160        mutex_unlock(&chrdevs_lock);\r\n 161        kfree(cd);\r\n 162        return ERR_PTR(ret);\r\n 163}<\/pre>\n
\u81f3\u6b64\uff0c\u6211\u4eec\u5df2\u7ecf\u5206\u6790\u5b8c\u4e86\u5b57\u7b26\u8bbe\u5907\u53f7\u5206\u914d\u51fd\u6570\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u5982\u4f55\u627e\u5230\u4e00\u4e2a\u6709\u6548\u7684\u5207\u5165\u70b9\u53bb\u6df1\u5165\u5206\u6790\u5185\u6838\u6e90\u7801\uff0c\u8fd9\u662f\u4e00\u4e2a\u4ee4\u4eba\u6df1\u601d\u7684\u95ee\u9898\u3002\u672c\u6587\u4ee5\u524d\u6587\u4e2d\u672a\u8be6\u7ec6\u8bf4\u660e\u7684\u51fd\u6570\u4e3a\u5207\u5165\u70b9\uff0c\u6df1\u5165 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[110],"tags":[134,108,151],"class_list":["post-1393","post","type-post","status-publish","format-standard","hentry","category-linux","tag-kernel","tag-linux","tag-151"],"views":15551,"_links":{"self":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/1393","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/comments?post=1393"}],"version-history":[{"count":2,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/1393\/revisions"}],"predecessor-version":[{"id":4381,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/1393\/revisions\/4381"}],"wp:attachment":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/media?parent=1393"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/categories?post=1393"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/tags?post=1393"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}