linux-kernel - [PATCH] __exit_signal: don't take rcu lock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:	Sat, 31 May 2008 20:15:27 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] __exit_signal: don't take rcu lock

There is no reason for rcu_read_lock() in __exit_signal(). tsk->sighand can
only be changed if tsk does exec, obviously this is not possible.

Signed-off-by: Oleg Nesterov <oleg@...sign.ru>

--- 26-rc2/kernel/exit.c~0_ES_NO_RCU	2008-05-26 18:09:12.000000000 +0400
+++ 26-rc2/kernel/exit.c	2008-05-31 20:08:11.000000000 +0400
@@ -84,7 +84,6 @@ static void __exit_signal(struct task_st
 	BUG_ON(!sig);
 	BUG_ON(!atomic_read(&sig->count));
 
-	rcu_read_lock();
 	sighand = rcu_dereference(tsk->sighand);
 	spin_lock(&sighand->siglock);
 
@@ -135,7 +134,6 @@ static void __exit_signal(struct task_st
 	tsk->signal = NULL;
 	tsk->sighand = NULL;
 	spin_unlock(&sighand->siglock);
-	rcu_read_unlock();
 
 	__cleanup_sighand(sighand);
 	clear_tsk_thread_flag(tsk,TIF_SIGPENDING);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/