Messages in this thread Patch in this message | | | Date | Fri, 5 Dec 2014 15:25:33 -0800 | From | tip-bot for Thomas Gleixner <> | Subject | [tip:x86/apic] x86, smpboot: Remove pointless preempt_disable() in native_smp_prepare_cpus() |
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Commit-ID: dd60143c04f257bace7c8d805eb1f4aec461b138 Gitweb: http://git.kernel.org/tip/dd60143c04f257bace7c8d805eb1f4aec461b138 Author: Thomas Gleixner <tglx@linutronix.de> AuthorDate: Fri, 5 Dec 2014 08:48:29 +0000 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Sat, 6 Dec 2014 00:19:25 +0100
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 <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> --- 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 4d2128a..2dc789d 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)
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