From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753922AbcDSKTQ (ORCPT ); Tue, 19 Apr 2016 06:19:16 -0400 Received: from mail-pa0-f67.google.com ([209.85.220.67]:34526 "EHLO mail-pa0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753480AbcDSKTO (ORCPT ); Tue, 19 Apr 2016 06:19:14 -0400 From: Kautuk Consul To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Anton Blanchard , Cyril Bur , Michael Neuling , Anshuman Khandual Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Kautuk Consul Subject: [PATCH 1/1] powerpc: get_wchan(): solve possible race scenario due to parallel wakeup Date: Tue, 19 Apr 2016 15:48:21 +0530 Message-Id: <1461061101-31196-1-git-send-email-kautuk.consul.1980@gmail.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a check for p->state == TASK_RUNNING so that any wake-ups on task_struct p in the interim lead to 0 being returned by get_wchan(). Signed-off-by: Kautuk Consul --- arch/powerpc/kernel/process.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index b8500b4..f233352 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1785,7 +1785,8 @@ unsigned long get_wchan(struct task_struct *p) do { sp = *(unsigned long *)sp; - if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD)) + if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD) || + p->state == TASK_RUNNING) return 0; if (count > 0) { ip = ((unsigned long *)sp)[STACK_FRAME_LR_SAVE]; -- 1.7.9.5