Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756086Ab1E2XNP (ORCPT ); Sun, 29 May 2011 19:13:15 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:54798 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754295Ab1E2XNC (ORCPT ); Sun, 29 May 2011 19:13:02 -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=dqqDk7GwxiYrczserMCB6//zfP7D0OSdP0yNaH0sPp21UUjfUD+TaX9EsQHDxIeBi2 lPs1Y2ZKahym4YROBALii8/XOFOPuDfMMJtQbuZ3+9gUFVGqS2HQuTcZsJ50BjaFghjt csubwxOQE9uUv+1Ruh+q5RYvVfbV4q27xYgqs= 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 08/17] ptrace: use bit_waitqueue for TRAPPING instead of wait_chldexit Date: Mon, 30 May 2011 01:12:31 +0200 Message-Id: <1306710760-16440-9-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.7.5.2 In-Reply-To: <1306710760-16440-1-git-send-email-tj@kernel.org> References: <1306710760-16440-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2279 Lines: 72 ptracer->signal->wait_chldexit was used to wait for TRAPPING; however, ->wait_chldexit was already complicated with waker-side filtering without adding TRAPPING wait on top of it. Also, it unnecessarily made TRAPPING clearing depend on the current ptrace relationship - if the ptracee is detached, wakeup is lost. There is no reason to use signal->wait_chldexit here. We're just waiting for JOBCTL_TRAPPING bit to clear and given the relatively infrequent use of ptrace, bit_waitqueue can serve it perfectly. This patch makes JOBCTL_TRAPPING wait use bit_waitqueue instead of signal->wait_chldexit. -v2: Use JOBCTL_*_BIT macros instead of ilog2() as suggested by Linus. Signed-off-by: Tejun Heo Cc: Linus Torvalds --- kernel/ptrace.c | 10 ++++++++-- kernel/signal.c | 3 +-- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 1506556..82f566b 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -25,6 +25,12 @@ #include +static int ptrace_trapping_sleep_fn(void *flags) +{ + schedule(); + return 0; +} + /* * ptrace a task: make the debugger its new parent and * move it to the ptrace list. @@ -269,8 +275,8 @@ unlock_tasklist: unlock_creds: mutex_unlock(&task->signal->cred_guard_mutex); out: - wait_event(current->signal->wait_chldexit, - !(task->jobctl & JOBCTL_TRAPPING)); + wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, + ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE); return retval; } diff --git a/kernel/signal.c b/kernel/signal.c index 9ab91c5..172a4c7 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -272,8 +272,7 @@ static void task_clear_jobctl_trapping(struct task_struct *task) { if (unlikely(task->jobctl & JOBCTL_TRAPPING)) { task->jobctl &= ~JOBCTL_TRAPPING; - __wake_up_sync_key(&task->parent->signal->wait_chldexit, - TASK_UNINTERRUPTIBLE, 1, task); + wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT); } } -- 1.7.5.2 -- 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/