Messages in this thread | | | Subject | Re: [PATCH] simplify/fix first_tid() | From | (Eric W. Biederman) | Date | Mon, 20 Mar 2006 11:00:59 -0700 |
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Oleg Nesterov <oleg@tv-sign.ru> writes:
> first_tid: > > /* If nr exceeds the number of threads there is nothing todo */ > if (nr) { > if (nr >= get_nr_threads(leader)) > goto done; > } > > This is not reliable: sub-threads can exit after this check, so the > 'for' loop below can overlap and proc_task_readdir() can return an > already filldir'ed dirents. > > for (; pos && pid_alive(pos); pos = next_thread(pos)) { > if (--nr > 0) > continue; > > Off-by-one error, will return 'leader' when nr == 1. > > This patch tries to fix these problems and simplify the code.
This is better however if I read this code correctly. It modifies the code so the last time user space goes trough this loop with nr > nr_threads. Then we will walk the entire threads list to achieve nothing.
So we really still need the nr_threads test in there so we don't traverse the list twice everytime through readdir.
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