From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f179.google.com (mail-ob0-f179.google.com [209.85.214.179]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id BF124B6FEE for ; Mon, 23 Apr 2012 17:10:42 +1000 (EST) Received: by mail-ob0-f179.google.com with SMTP id uo19so7505922obb.38 for ; Mon, 23 Apr 2012 00:10:42 -0700 (PDT) Date: Mon, 23 Apr 2012 00:09:25 -0700 From: Anton Vorontsov To: Andrew Morton , Oleg Nesterov Subject: [PATCH 7/9] um: Should hold tasklist_lock while traversing processes Message-ID: <20120423070925.GG30752@lizard> References: <20120423070641.GA27702@lizard> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: <20120423070641.GA27702@lizard> Cc: linaro-kernel@lists.linaro.org, Mike Frysinger , Peter Zijlstra , user-mode-linux-devel@lists.sourceforge.net, linux-sh@vger.kernel.org, Richard Weinberger , patches@linaro.org, linux-kernel@vger.kernel.org, uclinux-dist-devel@blackfin.uclinux.org, linux-mm@kvack.org, Paul Mundt , John Stultz , KOSAKI Motohiro , Russell King , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Traversing the tasks requires holding tasklist_lock, otherwise it is unsafe. p.s. However, I'm not sure that calling os_kill_ptraced_process() in the atomic context is correct. It seem to work, but please take a closer look. Signed-off-by: Anton Vorontsov --- arch/um/kernel/reboot.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/um/kernel/reboot.c b/arch/um/kernel/reboot.c index 4d93dff..66d754c 100644 --- a/arch/um/kernel/reboot.c +++ b/arch/um/kernel/reboot.c @@ -4,6 +4,7 @@ */ #include "linux/sched.h" +#include "linux/spinlock.h" #include "linux/slab.h" #include "kern_util.h" #include "os.h" @@ -22,6 +23,7 @@ static void kill_off_processes(void) struct task_struct *p; int pid; + read_lock(&tasklist_lock); for_each_process(p) { if (p->mm == NULL) continue; @@ -29,6 +31,7 @@ static void kill_off_processes(void) pid = p->mm->context.id.u.pid; os_kill_ptraced_process(pid, 1); } + read_unlock(&tasklist_lock); } } -- 1.7.9.2