Hello, I'm dealing with a problem in a kernel module that get data from userspace using a /proc entry.

I set open/write/release entries for my own defined /proc entry, and manage well to use it to get data from userspace. I handle errors in open/write functions well, and they are visible to user as open/fopen or write/fwrite/fprintf errors.

But some of the errors can only be checked at close (because it's the time all the data is available). In these cases I return something different than 0, which I supposed to be in some way the value 'close' or 'fclose' will return to user.

But whatever the value I return my close behave like if all is fine. To be sure I replaced all the release() code by a simple 'return(-1);' and wrote a program that open/write/close the /proc entry, and prints the close return value (and the errno). It always return '0' whatever the value I give.

Behavior is the same with 'fclose', or by using shell mechanism (echo "..." >/proc/my/entry).

Any clue about this strange behavior that is not the one claimed in many tutorials I found?

BTW I'm using RHEL5 kernel (2.6.18, redhat modified), on a 64bit system.

Thanks.

Regards,

Yannick