From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Shi, Yang" Subject: Re: [PATCH] arm64: replace read_lock to rcu lock in call_break_hook Date: Thu, 01 Oct 2015 09:03:05 -0700 Message-ID: <560D5939.7080107@linaro.org> References: <1443653944-21885-1-git-send-email-yang.shi@linaro.org> <20151001150735.GH6963@e104818-lin.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: rostedt@goodmis.org, will.deacon@arm.com, dave.long@linaro.org, panand@redhat.com, linaro-kernel@lists.linaro.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rt-users@vger.kernel.org To: Catalin Marinas Return-path: Received: from mail-pa0-f41.google.com ([209.85.220.41]:36175 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750844AbbJAQDH (ORCPT ); Thu, 1 Oct 2015 12:03:07 -0400 Received: by pablk4 with SMTP id lk4so77840825pab.3 for ; Thu, 01 Oct 2015 09:03:07 -0700 (PDT) In-Reply-To: <20151001150735.GH6963@e104818-lin.cambridge.arm.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 10/1/2015 8:07 AM, Catalin Marinas wrote: > On Wed, Sep 30, 2015 at 03:59:04PM -0700, Yang Shi wrote: >> diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c >> index cebf786..eb520d0 100644 >> --- a/arch/arm64/kernel/debug-monitors.c >> +++ b/arch/arm64/kernel/debug-monitors.c >> @@ -292,11 +292,11 @@ static int call_break_hook(struct pt_regs *regs, unsigned int esr) >> struct break_hook *hook; >> int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL; >> >> - read_lock(&break_hook_lock); >> + rcu_read_lock(); >> list_for_each_entry(hook, &break_hook, node) >> if ((esr & hook->esr_mask) == hook->esr_val) >> fn = hook->fn; >> - read_unlock(&break_hook_lock); >> + rcu_read_unlock(); >> >> return fn ? fn(regs, esr) : DBG_HOOK_ERROR; >> } > > That's not enough, you also need list_(add|del)_rcu where the list is > modified, together with list_for_each_entry_rcu() here. Thanks for pointing it out. I'm going to prepare v2 with list_(add|del)_rcu. Yang >