Re: Is this racy?

[Daniel Jacobowitz <dan@debian.org>]

On Mon, Oct 07, 2002 at 02:51:52PM -0600, Michal Jaegermann wrote:
> In fs/proc/array.c (2.4.20-pre9, 2.4.19 and likely many other
> versions) in function 'proc_pid_stat()' there is a code like that:
> 
> 	......
> 	read_lock(&tasklist_lock);
> 	ppid = task->pid ? task->p_opptr->pid : 0;
> 	read_unlock(&tasklist_lock);
> 	res = sprintf(buffer,"<long format string>",
> 		task->pid,
> 		......
> 		ppid,
> 		......
> 
> So assignment to ppid is locked but other reads from fiels of 'task'
> structure are not guarded that way.  Is this ok or if not we do not
> particularly care?  Function 'task_state()' in the same file seems
> to be more careful about this.

I think the lock is just so that p_opptr->pid doesn't change while
we're looking at it.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer