Question

我想创建一个sysfs条目，使用＆＃34;属性＆＃34;结构体。建议这样做的方法是使用__ATTR宏，如下所示：

static ssize_t functionCalledOnRead(struct kobject *, struct attribute *, char *);
static ssize_t functionCalledOnRead(struct kobject *, struct attribute *, char *);

static struct attribute genericSysfsAttribute = __ATTR(attr_name, S_IRUGO | S_IRUSR, functionCalledOnRead, functionCalledOnWrite);

然而，这不起作用。

/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:15: warning: braces around scalar initializer
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:15: warning: (near initialization for 'genericSysfsAttribute.name')
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:15: error: field name not in record or union initializer
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:15: error: (near initialization for 'genericSysfsAttribute.name')
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:15: error: field name not in record or union initializer
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:15: error: (near initialization for 'genericSysfsAttribute.name')
In file included from include/linux/thread_info.h:11:0,
                 from include/asm-generic/preempt.h:4,
                 from arch/arm/include/generated/asm/preempt.h:1,
                 from include/linux/preempt.h:59,
                 from include/linux/spinlock.h:50,
                 from include/linux/seqlock.h:35,
                 from include/linux/time.h:5,
                 from include/linux/stat.h:18,
                 from include/linux/module.h:10,
                 from /home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:2:
include/linux/bug.h:34:45: warning: excess elements in scalar initializer
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
include/linux/bug.h:34:45: warning: (near initialization for 'genericSysfsAttribute.name')
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
include/linux/bug.h:34:45: error: unknown field 'show' specified in initializer
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
include/linux/bug.h:34:45: warning: initialization makes integer from pointer without a cast
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
include/linux/bug.h:34:45: warning: (near initialization for 'genericSysfsAttribute.mode')
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
include/linux/bug.h:34:45: error: initializer element is not computable at load time
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
include/linux/bug.h:34:45: error: (near initialization for 'genericSysfsAttribute.mode')
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
include/linux/bug.h:34:45: error: unknown field 'store' specified in initializer
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
include/linux/bug.h:34:45: warning: excess elements in struct initializer
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
include/linux/bug.h:34:45: warning: (near initialization for 'genericSysfsAttribute')
 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
                                             ^
include/linux/kernel.h:842:3: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
   BUILD_BUG_ON_ZERO((perms) & 2) +     \
   ^
include/linux/sysfs.h:102:12: note: in expansion of macro 'VERIFY_OCTAL_PERMISSIONS'
    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },  \
            ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:49: note: in expansion of macro '__ATTR'
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                                                 ^
/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.c:32:25: warning: 'genericSysfsAttribute' defined but not used [-Wunused-variable]
 static struct attribute genericSysfsAttribute = __ATTR(attr_name,S_IRUGO | S_IRUSR,functionCalledOnRead,functionCalledOnWrite);
                         ^
scripts/Makefile.build:297: recipe for target '/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.o' failed
make[2]: *** [/home/osboxes/Documents/kernel_modules/sysfsmodule/sysfsmodule.o] Error 1
Makefile:1425: recipe for target '_module_/home/osboxes/Documents/kernel_modules/sysfsmodule' failed
make[1]: *** [_module_/home/osboxes/Documents/kernel_modules/sysfsmodule] Error 2
make[1]: Leaving directory '/home/osboxes/Documents/linux-mykonos'
Makefile:7: recipe for target 'cross' failed
make: *** [cross] Error 2

我真的不明白大多数错误在说什么，因为他们正在谈论包含的代码，而不是我写的内容。但是，由于第一个参数只是一个名称，第二个参数只是一个数字，我不认为这些有任何问题，所以它似乎与我如何给出这两个名称有关。功能不起作用。如何传递这样的函数？

Answer 1

宏if df['time'].total_seconds() == 291.0: print("true")不是直接使用，而是供子系统开发人员使用，他们为kobject定义类型并创建属性结构＆＃34;衍生＆＃34;来自__ATTR。

此外，普通struct attribute有a little sence：

裸属性不包含读取或写入值的方法属性。鼓励子系统定义自己的属性用于添加和删除属性的结构和包装函数特定的对象类型。

Answer 2

由于传递给宏的模式值S_IRUGO|S_IRUSR引起错误。在<linux/kernel.h>模块中，如果权限违反以下任一条件，则权限检查将引发错误：

USER_READABLE> = GROUP_READABLE> = OTHER_READABLE
<777和> 0
USER_WRITABLE> = GROUP_WRITABLE
OTHER_WRITABLE = 0（不允许在此处写入内容不是一个好主意）

如何在Linux内核中使用__ATTR宏？

2 个答案: