unsigned long copy_from_user (void * to, const void __user * from, unsigned long n);
to
Destination address, in kernel space.
fromSource address, in user space.
nNumber of bytes to copy.
User context only. This function may sleep.
Copy data from user space to kernel space.
Returns number of bytes that could not be copied. On success, this will be zero.
If some data could not be copied, this function will pad the copied data to the requested size using zero bytes.
unsigned long copy_to_user (void __user * to, const void * from, unsigned long n);
to
Destination address, in user space.
fromSource address, in kernel space.
nNumber of bytes to copy.
User context only. This function may sleep.
Copy data from kernel space to user space.
Returns number of bytes that could not be copied. On success, this will be zero.
put_user ( x, ptr);
x
Value to copy to user space.
ptrDestination address, in user space.
User context only. This function may sleep.
This macro copies a single simple value from kernel space to user space. It supports simple types like char and int, but not larger data types like structures or arrays.
ptr must have pointer-to-simple-variable type, and x must be assignable to the result of dereferencing ptr.
Returns zero on success, or -EFAULT on error.
get_user ( x, ptr);
x
Variable to store result.
ptrSource address, in user space.
User context only. This function may sleep.
This macro copies a single simple variable from user space to kernel space. It supports simple types like char and int, but not larger data types like structures or arrays.
ptr must have pointer-to-simple-variable type, and the result of dereferencing ptr must be assignable to x without a cast.
Returns zero on success, or -EFAULT on error. On error, the variable x is set to zero.
转自：http://blogold.chinaunix.net/u/20947/showart_234319.html
