Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751308AbdLAVbr (ORCPT ); Fri, 1 Dec 2017 16:31:47 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:48580 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750965AbdLAVbq (ORCPT ); Fri, 1 Dec 2017 16:31:46 -0500 Date: Fri, 1 Dec 2017 13:31:40 -0800 From: Sukadev Bhattiprolu To: Michael Ellerman Cc: clombard@linux.vnet.ibm.com, felix@linux.vnet.ibm.com, vaibhav@linux.vnet.ibm.com, linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/1]: powerpc: block interrupts when updating TIDR MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Operating-System: Linux 2.0.32 on an i486 User-Agent: Mutt/1.7.1 (2016-10-04) X-TM-AS-GCONF: 00 x-cbid: 17120121-0020-0000-0000-00000D193732 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008137; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000243; SDB=6.00954033; UDB=6.00482105; IPR=6.00734108; BA=6.00005726; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00018295; XFM=3.00000015; UTC=2017-12-01 21:31:43 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17120121-0021-0000-0000-00005F22604E Message-Id: <20171201213140.GA2776@us.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-12-01_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1712010256 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1909 Lines: 64 From: Sukadev Bhattiprolu Date: Tue, 28 Nov 2017 13:39:43 -0600 Subject: [PATCH 1/1]: powerpc: block interrupts when updating TIDR 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. Signed-off-by: Sukadev Bhattiprolu --- arch/powerpc/kernel/process.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index bfdd783..aa8dbb9 100644 --- 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 @@ static int assign_thread_tidr(void) 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 @@ static int assign_thread_tidr(void) 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); } /* -- 2.7.4