From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08BA5C04AAF for ; Tue, 21 May 2019 09:20:33 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CE3332173E for ; Tue, 21 May 2019 09:20:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Kn1Cz+yy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE3332173E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=Oaf5aC7trsXarxpudugURlgXN2UVFJgSwrPgNjQa4Ao=; b=Kn1 Cz+yybmJTB+tq0AzDDh4EjUocxvwtNW+S7Pk0a9bLlktkdlNsfMD5JahBO7VlgfLGRXsnhRLi2QNB BeEQYvYx8sghxncfbBtAM3anDHDGPgS5B+sEpa3zxvJmKwQIlWF2voYNzeckdnRx4gXTwD33pdgzL 2BVS5kw/r0Ig0VcKqfkdJoOodUR/03mAStDV1BPuHChrbfwW26Yh58I7vidVbxYUMcqhK7HOsoNMj BsHS7VCAIsKUuhYC91VBUUYiVVLwEi8HX2cOCSiZB58RGv0P4umzQygw2ixr548gkH/V8BTwPoB90 HeMlFS8UlbtSsdCIElozocSfjRs1AfQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hT0wf-0000YM-DD; Tue, 21 May 2019 09:20:29 +0000 Received: from alexa-out-tai-02.qualcomm.com ([103.229.16.227]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hT0wb-0000Xk-Qh for linux-arm-kernel@lists.infradead.org; Tue, 21 May 2019 09:20:27 +0000 Received: from ironmsg03-tai.qualcomm.com ([10.249.140.8]) by alexa-out-tai-02.qualcomm.com with ESMTP; 21 May 2019 17:20:20 +0800 X-IronPort-AV: E=McAfee;i="5900,7806,9263"; a="29754389" Received: from c-fan-gv.ap.qualcomm.com (HELO c-fan-gv) ([10.231.253.105]) by ironmsg03-tai.qualcomm.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 21 May 2019 17:20:08 +0800 From: Tengfei Fan To: catalin.marinas@arm.com, will.deacon@arm.com Subject: [PATCH] arm64: break while loop if task had been rescheduled Date: Tue, 21 May 2019 17:20:04 +0800 Message-Id: <1558430404-4840-1-git-send-email-tengfeif@codeaurora.org> X-Mailer: git-send-email 1.9.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190521_022026_162037_F921DCCF X-CRM114-Status: GOOD ( 11.94 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, tengfei@codeaurora.org, Tengfei Fan , anshuman.khandual@arm.com, marc.zyngier@arm.com, andreyknvl@google.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org While printing a task's backtrace and this task isn't current task, it is possible that task's fp and fp+8 have the same value, so cannot break the while loop. This can break while loop if this task had been rescheduled during print this task's backtrace. Signed-off-by: Tengfei Fan --- arch/arm64/kernel/traps.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 2975598..9df6e02 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -103,6 +103,9 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) { struct stackframe frame; int skip = 0; + long cur_state = 0; + unsigned long cur_sp = 0; + unsigned long cur_fp = 0; pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); @@ -127,6 +130,9 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) */ frame.fp = thread_saved_fp(tsk); frame.pc = thread_saved_pc(tsk); + cur_state = tsk->state; + cur_sp = thread_saved_sp(tsk); + cur_fp = frame.fp; } #ifdef CONFIG_FUNCTION_GRAPH_TRACER frame.graph = 0; @@ -134,6 +140,23 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) printk("Call trace:\n"); do { + if (tsk != current && (cur_state != tsk->state + /* + * We would not be printing backtrace for the task + * that has changed state from uninterruptible to + * running before hitting the do-while loop but after + * saving the current state. If task is in running + * state before saving the state, then we may print + * wrong call trace or end up in infinite while loop + * if *(fp) and *(fp+8) are same. While the situation + * will stop print when that task schedule out. + */ + || cur_sp != thread_saved_sp(tsk) + || cur_fp != thread_saved_fp(tsk))) { + printk("The task:%s had been rescheduled!\n", + tsk->comm); + break; + } /* skip until specified stack frame */ if (!skip) { dump_backtrace_entry(frame.pc); -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel