EXPORT_SYMBOL宏正在产生冲突类型错误

Question

我正在尝试将一个符号导出到内核。但是我得到了下面的错误。我的linux版本是5.4.2，

/home/ram/checkout/drivers/char/i2c_sw_hw_common.c: At top level:
/home/ram/checkout/drivers/char/i2c_sw_hw_common.c:1031:14: error: conflicting types  for ‘sfp_i2c_in32’
 UInt32 sfp_i2c_in32(char_dev_t *dev,unsigned int I2cDevaddr, int alen, unsigned int offset,unsigned int I2cAddr,int Width, int AccessType)
          ^~~~~~~~~~~~
In file included from /home/ram/checkout/drivers/char/i2c_sw_hw_common.c:3:
/home/ram/checkout/drivers/char/i2c_sw_hw_common.h:123:8: note: previous declaration of ‘sfp_i2c_in32’ was here
 UInt32 sfp_i2c_in32(char_dev_t *dev,unsigned int I2cDevaddr, int alen, unsigned int offset,unsigned int I2cAddr,int Width, int AccessType);
    ^~~~~~~~~~~~
/home/ram/checkout/drivers/char/i2c_sw_hw_common.c: In function ‘sfp_i2c_in32’:
/home/ram/checkout/drivers/char/i2c_sw_hw_common.c:1035:18: warning: unused variable ‘byte_count’ [-Wunused-variable]
    unsigned int byte_count = 0 ;
              ^~~~~~~~~~
/home/ram/checkout/drivers/char/i2c_sw_hw_common.c: At top level:
/home/ram/checkout/drivers/char/i2c_sw_hw_common.c:1063:29: error: conflicting types for ‘sfp_i2c_in32’
 EXPORT_SYMBOL_NOVERS(sfp_i2c_in32);
                         ^~~~~~~
In file included from /home/ram/checkout/drivers/char/i2c_sw_hw_common.c:3:
/home/ram/checkout/drivers/char/i2c_sw_hw_common.h:123:8: note: previous declaration of ‘sfp_i2c_in32’ was here
 UInt32 sfp_i2c_in32(char_dev_t *dev,unsigned int I2cDevaddr, int alen, unsigned int offset,unsigned int I2cAddr,int Width, int AccessType);
    ^~~~~~~~~~~~
cc1: some warnings being treated as errors

这是我对这个符号的声明、定义和导出。

i2c_sw_hw_common.c

UInt32 sfp_i2c_in32(char_dev_t *dev,unsigned int I2cDevaddr, int alen, unsigned int offset,unsigned int I2cAddr,int Width, int AccessType)
{
    // code
}
EXPORT_SYMBOL(sfp_i2c_in32);

i2c_sw_hw_common.h

UInt32 sfp_i2c_in32(char_dev_t *dev,unsigned int I2cDevaddr, int alen, unsigned int offset,unsigned int I2cAddr,int Width, int AccessType);

Answer 1

问题在于如何使用用户定义的数据类型。我没有使用unsigned int，而是使用了用户定义的UInt32。

typedef unsigned long UInt32;

这通常不会造成任何问题，只要在头文件和源文件中都可以看到相同的定义。

但是在我的例子中，在源文件(.c)中，UInt32被当作宏处理，在预处理完成后被扩展为unsigned int。

但是在头文件中，UInt32仍然是用户定义的数据类型。所以编译器抛出了上面的错误。

在检查了预处理阶段的输出后，我了解了这一点(为此使用-save-temps标志)。

在预处理阶段之后，声明仍然是，

UInt32 sfp_i2c_in32(char_dev_t *dev,unsigned int I2cDevaddr, int alen, unsigned int offset,unsigned int I2cAddr,int Width, int AccessType);

但定义改为，

unsigned int sfp_i2c_in32(char_dev_t *dev,unsigned int I2cDevaddr, int alen, unsigned int offset,unsigned int I2cAddr,int Width, int AccessType)
{
    // code
}

因此，从我的代码中删除所有用户定义的数据类型，并且只使用预定义的数据类型。

以上问题的极简例子可以是，

// file.h
typedef unsigned long UInt32;

UInt32 f();



// file.c
#include "x.h"

#define UInt32 unsigned int

UInt32 f()
{
    return 0;
}

你会犯错误，

x.c:6:14: error: conflicting types for ‘f’
 UInt32 f()
        ^
In file included from x.c:2:0:
x.h:3:8: note: previous declaration of ‘f’ was here
 UInt32 f();
        ^