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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-02-15 22:13:24 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-02-15 10:21:23 -0800 |
| commit | 3f17da699431ec48540beabc55c54d4b5e66c8e7 (patch) | |
| tree | 0cc68e5daea5d4532a0225aa47cce193a32f6655 /kernel/fork.c | |
| parent | 7775aa7690c26b3c5606090a43533a7a7429eb91 (diff) | |
| download | lwn-3f17da699431ec48540beabc55c54d4b5e66c8e7.tar.gz lwn-3f17da699431ec48540beabc55c54d4b5e66c8e7.zip | |
[PATCH] fix kill_proc_info() vs CLONE_THREAD race
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>
Cc: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 8e88b374cee9..3683ce10f4a9 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1123,8 +1123,8 @@ static task_t *copy_process(unsigned long clone_flags, 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 long clone_flags, */ p->it_prof_expires = jiffies_to_cputime(1); } - - spin_unlock(¤t->sighand->siglock); } /* @@ -1189,6 +1187,7 @@ static task_t *copy_process(unsigned long clone_flags, nr_threads++; total_forks++; + spin_unlock(¤t->sighand->siglock); write_unlock_irq(&tasklist_lock); proc_fork_connector(p); return p; |