Re: [PATCH] Making it easy to add system calls

Linus Torvalds
2003-03-06T03:21:11Z

On Wed, 5 Mar 2003, george anzinger wrote:
>
> SYS_CALL(clock_nanosleep) \
>
> This will put "sys_clock_nanosleep" in the call table in entry.S and
> define the "__NR_clock_nanosleep" for unistd. The last entry of the
> enum is NR_syscalls, thus defineing and keeping this symbol current.

Me no likee.

The fact is, we add system calls maybe a few times a year. Having to
update two places instead of just one is not very onerous.

More importantly, the system call numbers should be something you have to
think about, and a setup that makes it easy to merge new system calls with
different numbers "by mistake" is a _bad_ setup.

Don't get me wrong - I'm not saying that "system calls should be hard to
add, because only real men should add system calls". But I _am_ saying
that it should be damn hard to add a system call by mistake at the wrong
number, which is something your patch makes a lot easier than the current
situation.

And I do believe that adding system calls should inherently be something
that you have to think twice about, even if one of the thoughs is just
literally writing out the number that you decided on. So while I don't
think it should be "hard", it should definitely not be made any easier
than it already is.

Linus