From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:41498 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965068AbeBUNHM (ORCPT ); Wed, 21 Feb 2018 08:07:12 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sukadev Bhattiprolu , Michael Ellerman Subject: [PATCH 4.15 020/163] powerpc/kernel: Block interrupts when updating TIDR Date: Wed, 21 Feb 2018 13:47:29 +0100 Message-Id: <20180221124531.267932292@linuxfoundation.org> In-Reply-To: <20180221124529.931834518@linuxfoundation.org> References: <20180221124529.931834518@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sukadev Bhattiprolu commit 384dfd627f1ee67d028e6f14c6e9bf5a1e2a7a24 upstream. clear_thread_tidr() is called in interrupt context as a part of delayed put of the task structure (i.e as a part of timer interrupt). To prevent a deadlock, block interrupts when holding vas_thread_id_lock to set/ clear TIDR for a task. Fixes: ec233ede4c86 ("powerpc: Add support for setting SPRN_TIDR") Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/process.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1509,14 +1509,15 @@ static int assign_thread_tidr(void) { int index; int err; + unsigned long flags; again: if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL)) return -ENOMEM; - spin_lock(&vas_thread_id_lock); + spin_lock_irqsave(&vas_thread_id_lock, flags); err = ida_get_new_above(&vas_thread_ida, 1, &index); - spin_unlock(&vas_thread_id_lock); + spin_unlock_irqrestore(&vas_thread_id_lock, flags); if (err == -EAGAIN) goto again; @@ -1524,9 +1525,9 @@ again: return err; if (index > MAX_THREAD_CONTEXT) { - spin_lock(&vas_thread_id_lock); + spin_lock_irqsave(&vas_thread_id_lock, flags); ida_remove(&vas_thread_ida, index); - spin_unlock(&vas_thread_id_lock); + spin_unlock_irqrestore(&vas_thread_id_lock, flags); return -ENOMEM; } @@ -1535,9 +1536,11 @@ again: static void free_thread_tidr(int id) { - spin_lock(&vas_thread_id_lock); + unsigned long flags; + + spin_lock_irqsave(&vas_thread_id_lock, flags); ida_remove(&vas_thread_ida, id); - spin_unlock(&vas_thread_id_lock); + spin_unlock_irqrestore(&vas_thread_id_lock, flags); } /*