From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757223Ab1EXSm2 (ORCPT ); Tue, 24 May 2011 14:42:28 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:45008 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932816Ab1EXShx (ORCPT ); Tue, 24 May 2011 14:37:53 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:from:to:cc:subject:date:message-id:x-mailer:in-reply-to :references; b=L17FvUNYubQy0lem1TURS+8BxafmmHu1x5J75gYftBo/JLDRbKBtvUc2tKPFhj8X6j XSljcqfDnnbCI5X5zfmHv8kU1PakQ+UkozDtUFN9BwHzjYNjBNm3wD1HweXzwLiKijrX eVwZP15BxiC57dsSsV1T6Qr0KWB7PMf2k8TNs= From: Tejun Heo To: oleg@redhat.com Cc: vda.linux@googlemail.com, jan.kratochvil@redhat.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, indan@nul.nu, bdonlan@gmail.com, pedro@codesourcery.com, Tejun Heo Subject: [PATCH 03/19] ptrace: relocate set_current_state(TASK_TRACED) in ptrace_stop() Date: Tue, 24 May 2011 20:37:23 +0200 Message-Id: <1306262259-7285-4-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1306262259-7285-1-git-send-email-tj@kernel.org> References: <1306262259-7285-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In ptrace_stop(), after arch hook is done, the task state and jobctl bits are updated while holding siglock. The ordering requirement there is that TASK_TRACED is set before JOBCTL_TRAPPING is cleared to prevent ptracer waiting on TRAPPING doesn't end up waking up TRACED is actually set and sees TASK_RUNNING in wait(2). Move set_current_state(TASK_TRACED) to the top of the block and reorganize comments. This makes the ordering more obvious (TASK_TRACED before other updates) and helps future updates to group stop participation. This patch doesn't cause any functional change. Signed-off-by: Tejun Heo --- kernel/signal.c | 28 +++++++++++++--------------- 1 files changed, 13 insertions(+), 15 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 42d9bbd..eef44fd 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1733,6 +1733,18 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) } /* + * We're committing to trapping. TRACED should be visible before + * TRAPPING is cleared; otherwise, the tracer might fail do_wait(). + * Also, transition to TRACED and updates to ->jobctl should be + * atomic with respect to siglock and should be done after the arch + * hook as siglock is released and regrabbed across it. + */ + set_current_state(TASK_TRACED); + + current->last_siginfo = info; + current->exit_code = exit_code; + + /* * If @why is CLD_STOPPED, we're trapping to participate in a group * stop. Do the bookkeeping. Note that if SIGCONT was delievered * while siglock was released for the arch hook, PENDING could be @@ -1742,21 +1754,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING)) gstop_done = task_participate_group_stop(current); - current->last_siginfo = info; - current->exit_code = exit_code; - - /* - * TRACED should be visible before TRAPPING is cleared; otherwise, - * the tracer might fail do_wait(). - */ - set_current_state(TASK_TRACED); - - /* - * We're committing to trapping. Clearing JOBCTL_TRAPPING and - * transition to TASK_TRACED should be atomic with respect to - * siglock. This should be done after the arch hook as siglock is - * released and regrabbed across it. - */ + /* entering a trap, clear TRAPPING */ task_clear_jobctl_trapping(current); spin_unlock_irq(¤t->sighand->siglock); -- 1.7.1