Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261183AbVE2LXC (ORCPT ); Sun, 29 May 2005 07:23:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261196AbVE2LXC (ORCPT ); Sun, 29 May 2005 07:23:02 -0400 Received: from mail.tv-sign.ru ([213.234.233.51]:57516 "EHLO several.ru") by vger.kernel.org with ESMTP id S261183AbVE2LW6 (ORCPT ); Sun, 29 May 2005 07:22:58 -0400 Message-ID: <4299A7F6.3A31BB7D@tv-sign.ru> Date: Sun, 29 May 2005 15:31:02 +0400 From: Oleg Nesterov X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.2.20 i686) X-Accept-Language: en MIME-Version: 1.0 To: Trond Myklebust Cc: john cooper , linux-kernel@vger.kernel.org, Ingo Molnar , Olaf Kirch Subject: Re: RT and Cascade interrupts References: <42974F08.1C89CF2A@tv-sign.ru> <4297AF39.4070304@timesys.com> <42983135.C521F1C8@tv-sign.ru> <4298AED8.8000408@timesys.com> <1117312557.10746.6.camel@lade.trondhjem.org> Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1664 Lines: 59 __rpc_execute() calls ->tk_exit and goes to 'restarted' label. What if ->tk_exit calls rpc_sleep_on() ? If it is possible, we have a race. CPU_0 (main loop in rpc_execute restarted) CPU_1 rpc_delete_timer: if (RPC_IS_QUEUED()) // YES return; rpc_run_timer: rpc_wake_up_task: clear_bit(RPC_TASK_QUEUED) preemption, or long interrupt if (!RPC_IS_QUEUED()) // YES task->tk_action() __rpc_add_timer: set_bit(RPC_TASK_HAS_TIMER) mod_timer(); clear_bit(RPC_TASK_HAS_TIMER) Now we have pending timer without RPC_TASK_HAS_TIMER bit set. Is this patch makes any sense? Oleg. --- 2.6.12-rc5/net/sunrpc/sched.c~ Sun May 29 15:09:25 2005 +++ 2.6.12-rc5/net/sunrpc/sched.c Sun May 29 15:11:24 2005 @@ -135,8 +135,6 @@ __rpc_add_timer(struct rpc_task *task, r static void rpc_delete_timer(struct rpc_task *task) { - if (RPC_IS_QUEUED(task)) - return; if (test_and_clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate)) { del_singleshot_timer_sync(&task->tk_timer); dprintk("RPC: %4d deleting timer\n", task->tk_pid); @@ -566,7 +564,6 @@ static int __rpc_execute(struct rpc_task BUG_ON(RPC_IS_QUEUED(task)); - restarted: while (1) { /* * Garbage collection of pending timers... @@ -607,6 +604,7 @@ static int __rpc_execute(struct rpc_task unlock_kernel(); } + restarted: /* * Lockless check for whether task is sleeping or not. */ - 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/