[PATCH] do __unhash_process() under ->siglock
This patch moves __unhash_process() call from realease_task() to
__exit_signal(), so __detach_pid() is called with ->siglock held.
This means we don't need tasklist_lock to iterate over thread group anymore:
copy_process() was already changed to do attach_pid()
under ->siglock.
Eric's "pidhash-kill-switch_exec_pids.patch" from -mm
changed de_thread() so it doesn't touch PIDTYPE_TGID.
NOTE: de_thread() still needs some attention. It still changes task->pid
lockless. Taking ->sighand.siglock here allows to do more tasklist_lock
removals.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/exit.c b/kernel/exit.c
index 6b2e4cf..44d6c6e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -112,6 +112,8 @@
sig = NULL; /* Marker for below. */
}
+ __unhash_process(tsk);
+
tsk->signal = NULL;
cleanup_sighand(tsk);
spin_unlock(&sighand->siglock);
@@ -140,8 +142,6 @@
BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
__exit_signal(p);
- __unhash_process(p);
-
/*
* If we are the last non-leader member of the thread
* group, and the leader is zombie, then notify the