Messages in this thread Patch in this message | | | Date | Wed, 15 Feb 2006 22:13:24 +0300 | From | Oleg Nesterov <> | Subject | [PATCH 1/2] fix kill_proc_info() vs CLONE_THREAD race |
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There is a window after copy_process() unlocks ->sighand.siglock and before it adds the new thread to the thread list.
In that window __group_complete_signal(SIGKILL) will not see the new thread yet, so this thread will start running while the whole thread group was supposed to exit.
I beleive we have another good reason to place attach_pid(PID/TGID) under ->sighand.siglock. We can do the same for
release_task()->__unhash_process()
de_thread()->switch_exec_pids()
After that we don't need tasklist_lock to iterate over the thread list, and we can simplify things, see for example do_sigaction() or sys_times().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 2.6.16-rc3/kernel/fork.c~1_KILL 2006-02-15 22:52:07.000000000 +0300 +++ 2.6.16-rc3/kernel/fork.c 2006-02-15 23:21:51.000000000 +0300 @@ -1123,8 +1123,8 @@ static task_t *copy_process(unsigned lon p->real_parent = current; p->parent = p->real_parent; + spin_lock(¤t->sighand->siglock); if (clone_flags & CLONE_THREAD) { - spin_lock(¤t->sighand->siglock); /* * Important: if an exit-all has been started then * do not create this new thread - the whole thread @@ -1162,8 +1162,6 @@ static task_t *copy_process(unsigned lon */ p->it_prof_expires = jiffies_to_cputime(1); } - - spin_unlock(¤t->sighand->siglock); } /* @@ -1189,6 +1187,7 @@ static task_t *copy_process(unsigned lon nr_threads++; total_forks++; + spin_unlock(¤t->sighand->siglock); write_unlock_irq(&tasklist_lock); proc_fork_connector(p); return p; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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