From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88166C43441 for ; Tue, 13 Nov 2018 18:08:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4C247223AE for ; Tue, 13 Nov 2018 18:08:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="p8cokIbJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C247223AE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732487AbeKNEHw (ORCPT ); Tue, 13 Nov 2018 23:07:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:35062 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732124AbeKNEHw (ORCPT ); Tue, 13 Nov 2018 23:07:52 -0500 Received: from devnote (unknown [64.114.255.97]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 82C01208A3; Tue, 13 Nov 2018 18:08:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1542132518; bh=xQP50kAjy7ARw8RyNNAdepQ8FvQgeYQCTvzx9owIpuk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=p8cokIbJeH5/IReIrE4En7S1dVYNGKIM9En8KW3rKIoMsalB9vVJ27OFm+93CjaGB tuxbLjwuFqdr+BuE/DLmmBeoUAGWRQyMitiL3h+N6lj525ugBbak62NwsN4f37jRWi L4Uh6959kBoRn3jRtvGqsdp7tXuZZ8wT9C8AyfLM= Date: Tue, 13 Nov 2018 10:08:36 -0800 From: Masami Hiramatsu To: paulmck@linux.ibm.com Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Naveen N. Rao" , Anil S Keshavamurthy , "David S. Miller" Subject: Re: [PATCH tip/core/rcu 20/41] kprobes: eplace synchronize_sched() with synchronize_rcu() Message-Id: <20181113100836.567dcbdafa13546928b62d7a@kernel.org> In-Reply-To: <20181112031916.GF4170@linux.ibm.com> References: <20181111194104.GA4787@linux.ibm.com> <20181111194410.6368-20-paulmck@linux.ibm.com> <20181112120048.12b3fb7549f4b292fea1eefd@kernel.org> <20181112031916.GF4170@linux.ibm.com> X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.30; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 11 Nov 2018 19:19:16 -0800 "Paul E. McKenney" wrote: > On Mon, Nov 12, 2018 at 12:00:48PM +0900, Masami Hiramatsu wrote: > > On Sun, 11 Nov 2018 11:43:49 -0800 > > "Paul E. McKenney" wrote: > > > > > Now that synchronize_rcu() waits for preempt-disable regions of code > > > as well as RCU read-side critical sections, synchronize_sched() can be > > > replaced by synchronize_rcu(). This commit therefore makes this change. > > > > Would you mean synchronize_rcu() can ensure that any interrupt handler > > (which should run under preempt-disable state) run out (even on non-preemptive > > kernel)? > > Yes, but only as of this merge window. See this commit: > > 3e3100989869 ("rcu: Defer reporting RCU-preempt quiescent states when disabled") OK, I also found that now those are same. 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds") Acked-by: Masami Hiramatsu Thank you! > > Don't try this in v4.19 or earlier, but v4.20 and later is OK. ;-) > > Thanx, Paul > > > If so, I agree with these changes. > > > > Thank you, > > > > > > > > Signed-off-by: Paul E. McKenney > > > Cc: "Naveen N. Rao" > > > Cc: Anil S Keshavamurthy > > > Cc: "David S. Miller" > > > Cc: Masami Hiramatsu > > > --- > > > kernel/kprobes.c | 10 +++++----- > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > > > index 90e98e233647..08e31d863191 100644 > > > --- a/kernel/kprobes.c > > > +++ b/kernel/kprobes.c > > > @@ -229,7 +229,7 @@ static int collect_garbage_slots(struct kprobe_insn_cache *c) > > > struct kprobe_insn_page *kip, *next; > > > > > > /* Ensure no-one is interrupted on the garbages */ > > > - synchronize_sched(); > > > + synchronize_rcu(); > > > > > > list_for_each_entry_safe(kip, next, &c->pages, list) { > > > int i; > > > @@ -1382,7 +1382,7 @@ static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p) > > > if (ret) { > > > ap->flags |= KPROBE_FLAG_DISABLED; > > > list_del_rcu(&p->list); > > > - synchronize_sched(); > > > + synchronize_rcu(); > > > } > > > } > > > } > > > @@ -1597,7 +1597,7 @@ int register_kprobe(struct kprobe *p) > > > ret = arm_kprobe(p); > > > if (ret) { > > > hlist_del_rcu(&p->hlist); > > > - synchronize_sched(); > > > + synchronize_rcu(); > > > goto out; > > > } > > > } > > > @@ -1776,7 +1776,7 @@ void unregister_kprobes(struct kprobe **kps, int num) > > > kps[i]->addr = NULL; > > > mutex_unlock(&kprobe_mutex); > > > > > > - synchronize_sched(); > > > + synchronize_rcu(); > > > for (i = 0; i < num; i++) > > > if (kps[i]->addr) > > > __unregister_kprobe_bottom(kps[i]); > > > @@ -1966,7 +1966,7 @@ void unregister_kretprobes(struct kretprobe **rps, int num) > > > rps[i]->kp.addr = NULL; > > > mutex_unlock(&kprobe_mutex); > > > > > > - synchronize_sched(); > > > + synchronize_rcu(); > > > for (i = 0; i < num; i++) { > > > if (rps[i]->kp.addr) { > > > __unregister_kprobe_bottom(&rps[i]->kp); > > > -- > > > 2.17.1 > > > > > > > > > -- > > Masami Hiramatsu > > > -- Masami Hiramatsu