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Commit 250a1ac6 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarBorislav Petkov <bp@alien8.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20141205084147.153643952@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 5db66334

arch/x86/kernel/smpboot.c

+1 −7
Original line number Diff line number Diff line
@@ -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)