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Commit 5876700c authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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[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: default avatarOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 35f5cad8

kernel/exit.c

+2 −2
Original line number Diff line number Diff line
@@ -112,6 +112,8 @@ static void __exit_signal(struct task_struct *tsk) 
		sig = NULL; /* Marker for below. */

	}



	__unhash_process(tsk);



	tsk->signal = NULL;

	cleanup_sighand(tsk);

	spin_unlock(&sighand->siglock);
@@ -140,8 +142,6 @@ repeat: 
	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