From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752215Ab2KXSCi (ORCPT ); Sat, 24 Nov 2012 13:02:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34616 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751864Ab2KXSCg (ORCPT ); Sat, 24 Nov 2012 13:02:36 -0500 Date: Sat, 24 Nov 2012 19:02:33 +0100 From: Oleg Nesterov To: Ingo Molnar , Peter Zijlstra , Srikar Dronamraju Cc: Ananth N Mavinakayanahalli , Anton Arapov , linux-kernel@vger.kernel.org Subject: [PATCH 3/4] uprobes: Kill UPROBE_RUN_HANDLER flag Message-ID: <20121124180233.GA30990@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121124180213.GA30963@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Simply remove UPROBE_RUN_HANDLER and the corresponding code. It can only help if uprobe has a single consumer, and in fact it is no longer needed after handler_chain() was changed to use ->register_rwsem, we simply can not race with uprobe_register(). Signed-off-by: Oleg Nesterov --- kernel/events/uprobes.c | 23 +++++------------------ 1 files changed, 5 insertions(+), 18 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 873c993..97c3874 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -83,10 +83,8 @@ static atomic_t uprobe_events = ATOMIC_INIT(0); /* Have a copy of original instruction */ #define UPROBE_COPY_INSN 0 -/* Dont run handlers when first register/ last unregister in progress*/ -#define UPROBE_RUN_HANDLER 1 /* Can skip singlestep */ -#define UPROBE_SKIP_SSTEP 2 +#define UPROBE_SKIP_SSTEP 1 struct uprobe { struct rb_node rb_node; /* node in the rb tree */ @@ -475,9 +473,6 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) { struct uprobe_consumer *uc; - if (!test_bit(UPROBE_RUN_HANDLER, &uprobe->flags)) - return; - down_read(&uprobe->register_rwsem); for (uc = uprobe->consumers; uc; uc = uc->next) uc->handler(uc, regs); @@ -825,13 +820,8 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) { - int err; - consumer_add(uprobe, uc); - err = register_for_each_vma(uprobe, true); - if (!err) /* TODO: pointless unless the first consumer */ - set_bit(UPROBE_RUN_HANDLER, &uprobe->flags); - return err; + return register_for_each_vma(uprobe, true); } static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) @@ -842,12 +832,9 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u return; err = register_for_each_vma(uprobe, false); - if (!uprobe->consumers) { - clear_bit(UPROBE_RUN_HANDLER, &uprobe->flags); - /* TODO : cant unregister? schedule a worker thread */ - if (!err) - delete_uprobe(uprobe); - } + /* TODO : cant unregister? schedule a worker thread */ + if (!uprobe->consumers && !err) + delete_uprobe(uprobe); } /* -- 1.5.5.1