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x86, smpboot: Remove pointless preempt_disable() in native_smp_prepare_cpus()

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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 <tglx@linutronix.de>
Tested-by: Borislav 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: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2014-12-05 08:48:29 +00:00
parent 5db66334a7
commit 250a1ac685
1 changed files with 1 additions and 7 deletions
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8
arch/x86/kernel/smpboot.c
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@ -1084,7 +1084,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
{ {
unsigned int i; unsigned int i;
preempt_disable();
smp_cpu_index_default(); smp_cpu_index_default();
/* /*
@ -1102,22 +1101,19 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
} }
set_cpu_sibling_map(0); set_cpu_sibling_map(0);
if (smp_sanity_check(max_cpus) < 0) { if (smp_sanity_check(max_cpus) < 0) {
pr_info("SMP disabled\n"); pr_info("SMP disabled\n");
disable_smp(); disable_smp();
goto out; return;
} }
default_setup_apic_routing(); default_setup_apic_routing();
preempt_disable();
if (read_apic_id() != boot_cpu_physical_apicid) { if (read_apic_id() != boot_cpu_physical_apicid) {
panic("Boot APIC ID in local APIC unexpected (%d vs %d)", panic("Boot APIC ID in local APIC unexpected (%d vs %d)",
read_apic_id(), boot_cpu_physical_apicid); read_apic_id(), boot_cpu_physical_apicid);
/* Or can we switch back to PIC here? */ /* Or can we switch back to PIC here? */
} }
preempt_enable();
connect_bsp_APIC(); connect_bsp_APIC();
@ -1151,8 +1147,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
uv_system_init(); uv_system_init();
set_mtrr_aps_delayed_init(); set_mtrr_aps_delayed_init();
out:
preempt_enable();
} }
void arch_enable_nonboot_cpus_begin(void) void arch_enable_nonboot_cpus_begin(void)