Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753756AbZDUDnZ (ORCPT ); Mon, 20 Apr 2009 23:43:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752486AbZDUDnL (ORCPT ); Mon, 20 Apr 2009 23:43:11 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:54911 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750966AbZDUDnK (ORCPT ); Mon, 20 Apr 2009 23:43:10 -0400 Message-ID: <49ED406F.2040401@cn.fujitsu.com> Date: Tue, 21 Apr 2009 11:41:35 +0800 From: Lai Jiangshan User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Stephen Hemminger CC: Paul Mackerras , paulmck@linux.vnet.ibm.com, Eric Dumazet , Evgeniy Polyakov , David Miller , kaber@trash.net, torvalds@linux-foundation.org, jeff.chua.linux@gmail.com, mingo@elte.hu, jengelh@medozas.de, r000n@r000n.net, linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, netdev@vger.kernel.org, benh@kernel.crashing.org, mathieu.desnoyers@polymtl.ca Subject: Re: [PATCH] netfilter: use per-cpu recursive lock (v11) References: <49E72E83.50702@trash.net> <20090416.153354.170676392.davem@davemloft.net> <20090416234955.GL6924@linux.vnet.ibm.com> <20090417012812.GA25534@linux.vnet.ibm.com> <20090418094001.GA2369@ioremap.net> <20090418141455.GA7082@linux.vnet.ibm.com> <20090420103414.1b4c490f@nehalam> <49ECBE0A.7010303@cosmosbay.com> <18924.59347.375292.102385@cargo.ozlabs.ibm.com> <20090420215827.GK6822@linux.vnet.ibm.com> <18924.64032.103954.171918@cargo.ozlabs.ibm.com> <20090420160121.268a8226@nehalam> In-Reply-To: <20090420160121.268a8226@nehalam> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1197 Lines: 44 Stephen Hemminger wrote: > +/** > + * xt_table_info_rdlock_bh - recursive read lock for xt table info > + * > + * Table processing calls this to hold off any changes to table > + * (on current CPU). Always leaves with bottom half disabled. > + * If called recursively, then assumes bh/preempt already disabled. > + */ > +void xt_info_rdlock_bh(void) > +{ > + struct xt_info_lock *lock; > + > + preempt_disable(); > + lock = &__get_cpu_var(xt_info_locks); > + if (likely(++lock->depth == 0)) Maybe I missed something. I think softirq may be still enabled here. So what happen when xt_info_rdlock_bh() called recursively here? > + spin_lock_bh(&lock->lock); > + preempt_enable_no_resched(); > +} > +EXPORT_SYMBOL_GPL(xt_info_rdlock_bh); > + Is this OK for you: void xt_info_rdlock_bh(void) { struct xt_info_lock *lock; local_bh_disable(); lock = &__get_cpu_var(xt_info_locks); if (likely(++lock->depth == 0)) spin_lock(&lock->lock); } Lai. -- 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/