From: Thomas Gleixner Date: Fri, 5 Dec 2014 08:48:29 +0000 (+0000) Subject: x86, smpboot: Remove pointless preempt_disable() in native_smp_prepare_cpus() X-Git-Tag: firefly_0821_release~176^2~2615^2~29 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=250a1ac685f147d4f4b2f132cfaffcce1a6792c1;p=firefly-linux-kernel-4.4.55.git x86, smpboot: Remove pointless preempt_disable() in native_smp_prepare_cpus() 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@kernel.org Link: http://lkml.kernel.org/r/20141205084147.153643952@linutronix.de Signed-off-by: Thomas Gleixner --- 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)