From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiang Liu Subject: [Patch v1 01/17] x86, smpboot: Remove pointless preempt_disable() in native_smp_prepare_cpus() Date: Wed, 17 Dec 2014 12:35:32 +0800 Message-ID: <1418790948-22804-2-git-send-email-jiang.liu@linux.intel.com> References: <1418790948-22804-1-git-send-email-jiang.liu@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1418790948-22804-1-git-send-email-jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Thomas Gleixner , Joerg Roedel , Benjamin Herrenschmidt , Ingo Molnar , "H. Peter Anvin" , Yinghai Lu , Borislav Petkov , x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Toshi Kani , Igor Mammedov , David Rientjes , Dave Hansen , Lan Tianyu Cc: Ingo Molnar , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Tony Luck , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jiang Liu List-Id: iommu@lists.linux-foundation.org From: Thomas Gleixner There is no reason to keep preemption disabled in this function. We only have two other threads live: kthreadd and idle. Neither of them is going to preempt. But that preempt_disable forces all the code inside to do GFP_ATOMIC allocations which is just insane. Remove it. Signed-off-by: Thomas Gleixner Tested-by: Borislav Petkov Cc: Jiang Liu Cc: Joerg Roedel Cc: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Link: http://lkml.kernel.org/r/20141205084147.153643952-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org Signed-off-by: Thomas Gleixner Signed-off-by: Jiang Liu --- arch/x86/kernel/smpboot.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 7a8f5845e8eb..6d7022c683e3 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1084,7 +1084,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) { unsigned int i; - preempt_disable(); smp_cpu_index_default(); /* @@ -1102,22 +1101,19 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) } set_cpu_sibling_map(0); - if (smp_sanity_check(max_cpus) < 0) { pr_info("SMP disabled\n"); disable_smp(); - goto out; + return; } default_setup_apic_routing(); - preempt_disable(); if (read_apic_id() != boot_cpu_physical_apicid) { panic("Boot APIC ID in local APIC unexpected (%d vs %d)", read_apic_id(), boot_cpu_physical_apicid); /* Or can we switch back to PIC here? */ } - preempt_enable(); connect_bsp_APIC(); @@ -1151,8 +1147,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) uv_system_init(); set_mtrr_aps_delayed_init(); -out: - preempt_enable(); } void arch_enable_nonboot_cpus_begin(void) -- 1.7.10.4