From patchwork Tue Feb 5 22:05:59 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Herton Ronaldo Krzesinski X-Patchwork-Id: 218374 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from chlorine.canonical.com (chlorine.canonical.com [91.189.94.204]) by ozlabs.org (Postfix) with ESMTP id 9955A2C02BE for ; Wed, 6 Feb 2013 09:08:20 +1100 (EST) Received: from localhost ([127.0.0.1] helo=chlorine.canonical.com) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1U2qgX-0001Aj-Pt; Tue, 05 Feb 2013 22:08:13 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1U2qgU-000191-Nq for kernel-team@lists.ubuntu.com; Tue, 05 Feb 2013 22:08:10 +0000 Received: from 189.58.24.194.dynamic.adsl.gvt.net.br ([189.58.24.194] helo=canonical.com) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1U2qgU-0003c4-1Q; Tue, 05 Feb 2013 22:08:10 +0000 From: Herton Ronaldo Krzesinski To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 10/93] ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone Date: Tue, 5 Feb 2013 20:05:59 -0200 Message-Id: <1360102042-10732-11-git-send-email-herton.krzesinski@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1360102042-10732-1-git-send-email-herton.krzesinski@canonical.com> References: <1360102042-10732-1-git-send-email-herton.krzesinski@canonical.com> X-Extended-Stable: 3.5 Cc: Russell King , Stephen Boyd X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.13 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: kernel-team-bounces@lists.ubuntu.com Errors-To: kernel-team-bounces@lists.ubuntu.com 3.5.7.5 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Stephen Boyd commit 568dca15aa2a0f4ddee255894ec393a159f13147 upstream. Patrik Kluba reports that the preempt count becomes invalid due to the preempt_enable() call being unbalanced with a preempt_disable() call in the vfp assembly routines. This happens because preempt_enable() and preempt_disable() update preempt counts under PREEMPT_COUNT=y but the vfp assembly routines do so under PREEMPT=y. In a configuration where PREEMPT=n and DEBUG_ATOMIC_SLEEP=y, PREEMPT_COUNT=y and so the preempt_enable() call in VFP_bounce() keeps subtracting from the preempt count until it goes negative. Fix this by always using PREEMPT_COUNT to decided when to update preempt counts in the ARM assembly code. Signed-off-by: Stephen Boyd Reported-by: Patrik Kluba Tested-by: Patrik Kluba Signed-off-by: Russell King Signed-off-by: Herton Ronaldo Krzesinski --- arch/arm/vfp/entry.S | 6 +++--- arch/arm/vfp/vfphw.S | 4 ++-- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm/vfp/entry.S b/arch/arm/vfp/entry.S index cc926c9..323ce1a 100644 --- a/arch/arm/vfp/entry.S +++ b/arch/arm/vfp/entry.S @@ -22,7 +22,7 @@ @ IRQs disabled. @ ENTRY(do_vfp) -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT ldr r4, [r10, #TI_PREEMPT] @ get preempt count add r11, r4, #1 @ increment it str r11, [r10, #TI_PREEMPT] @@ -35,7 +35,7 @@ ENTRY(do_vfp) ENDPROC(do_vfp) ENTRY(vfp_null_entry) -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT get_thread_info r10 ldr r4, [r10, #TI_PREEMPT] @ get preempt count sub r11, r4, #1 @ decrement it @@ -53,7 +53,7 @@ ENDPROC(vfp_null_entry) __INIT ENTRY(vfp_testing_entry) -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT get_thread_info r10 ldr r4, [r10, #TI_PREEMPT] @ get preempt count sub r11, r4, #1 @ decrement it diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S index 3a0efaa..6ff903e 100644 --- a/arch/arm/vfp/vfphw.S +++ b/arch/arm/vfp/vfphw.S @@ -167,7 +167,7 @@ vfp_hw_state_valid: @ else it's one 32-bit instruction, so @ always subtract 4 from the following @ instruction address. -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT get_thread_info r10 ldr r4, [r10, #TI_PREEMPT] @ get preempt count sub r11, r4, #1 @ decrement it @@ -191,7 +191,7 @@ look_for_VFP_exceptions: @ not recognised by VFP DBGSTR "not VFP" -#ifdef CONFIG_PREEMPT +#ifdef CONFIG_PREEMPT_COUNT get_thread_info r10 ldr r4, [r10, #TI_PREEMPT] @ get preempt count sub r11, r4, #1 @ decrement it