From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:39140 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754066AbeDJW2d (ORCPT ); Tue, 10 Apr 2018 18:28:33 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, NeilBrown , Andreas Dilger , Sasha Levin Subject: [PATCH 4.15 062/168] staging: lustre: disable preempt while sampling processor id. Date: Wed, 11 Apr 2018 00:23:24 +0200 Message-Id: <20180410212802.839699613@linuxfoundation.org> In-Reply-To: <20180410212800.144079021@linuxfoundation.org> References: <20180410212800.144079021@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: NeilBrown [ Upstream commit dbeccabf5294e80f7cc9ee566746c42211bed736 ] Calling smp_processor_id() without disabling preemption triggers a warning (if CONFIG_DEBUG_PREEMPT). I think the result of cfs_cpt_current() is only used as a hint for load balancing, rather than as a precise and stable indicator of the current CPU. So it doesn't need to be called with preemption disabled. So disable preemption inside cfs_cpt_current() to silence the warning. Signed-off-by: NeilBrown Reviewed-by: Andreas Dilger Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c +++ b/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c @@ -529,19 +529,20 @@ EXPORT_SYMBOL(cfs_cpt_spread_node); int cfs_cpt_current(struct cfs_cpt_table *cptab, int remap) { - int cpu = smp_processor_id(); - int cpt = cptab->ctb_cpu2cpt[cpu]; + int cpu; + int cpt; - if (cpt < 0) { - if (!remap) - return cpt; + preempt_disable(); + cpu = smp_processor_id(); + cpt = cptab->ctb_cpu2cpt[cpu]; + if (cpt < 0 && remap) { /* don't return negative value for safety of upper layer, * instead we shadow the unknown cpu to a valid partition ID */ cpt = cpu % cptab->ctb_nparts; } - + preempt_enable(); return cpt; } EXPORT_SYMBOL(cfs_cpt_current);