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| author | Tejun Heo <tj@kernel.org> | 2010-12-09 11:47:21 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2010-12-10 13:46:26 +0100 |
| commit | 0aa002fe602939370e9476e5ec32b562000a0425 (patch) | |
| tree | 9328b22674ec6eab144e464274f9f635fef37666 /arch | |
| parent | 0e3fa13f4ee110de007bca3bf395b77997319fc8 (diff) | |
| download | linux-stable-0aa002fe602939370e9476e5ec32b562000a0425.tar.gz linux-stable-0aa002fe602939370e9476e5ec32b562000a0425.tar.bz2 linux-stable-0aa002fe602939370e9476e5ec32b562000a0425.zip | |
x86: apic: Cleanup and simplify setup_local_APIC()
setup_local_APIC() is used to setup local APIC early during CPU
initialization and already assumes that preemption is disabled on
entry. However, The function unnecessarily disables and enables
preemption and uses smp_processor_id() multiple times in and out of
the nested preemption disabled section. This gives the wrong
impression that the function might be able to handle being called with
preemption enabled and/or migrated to another processor in the middle.
Make it clear that the function is always called with preemption
disabled, drop the confusing preemption disable block and call
smp_processor_id() once at the beginning of the function.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: brgerst@gmail.com
LKML-Reference: <4D00B3B9.7060702@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/apic/apic.c | 21 |
1 files changed, 9 insertions, 12 deletions
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 89339360b3d8..c0f6426cd337 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1195,12 +1195,15 @@ static void __cpuinit lapic_setup_esr(void) oldvalue, value); } - /** * setup_local_APIC - setup the local APIC + * + * Used to setup local APIC while initializing BSP or bringin up APs. + * Always called with preemption disabled. */ void __cpuinit setup_local_APIC(void) { + int cpu = smp_processor_id(); unsigned int value, queued; int i, j, acked = 0; unsigned long long tsc = 0, ntsc; @@ -1225,8 +1228,6 @@ void __cpuinit setup_local_APIC(void) #endif perf_events_lapic_init(); - preempt_disable(); - /* * Double-check whether this APIC is really registered. * This is meaningless in clustered apic mode, so we skip it. @@ -1342,21 +1343,19 @@ void __cpuinit setup_local_APIC(void) * TODO: set up through-local-APIC from through-I/O-APIC? --macro */ value = apic_read(APIC_LVT0) & APIC_LVT_MASKED; - if (!smp_processor_id() && (pic_mode || !value)) { + if (!cpu && (pic_mode || !value)) { value = APIC_DM_EXTINT; - apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n", - smp_processor_id()); + apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n", cpu); } else { value = APIC_DM_EXTINT | APIC_LVT_MASKED; - apic_printk(APIC_VERBOSE, "masked ExtINT on CPU#%d\n", - smp_processor_id()); + apic_printk(APIC_VERBOSE, "masked ExtINT on CPU#%d\n", cpu); } apic_write(APIC_LVT0, value); /* * only the BP should see the LINT1 NMI signal, obviously. */ - if (!smp_processor_id()) + if (!cpu) value = APIC_DM_NMI; else value = APIC_DM_NMI | APIC_LVT_MASKED; @@ -1364,11 +1363,9 @@ void __cpuinit setup_local_APIC(void) value |= APIC_LVT_LEVEL_TRIGGER; apic_write(APIC_LVT1, value); - preempt_enable(); - #ifdef CONFIG_X86_MCE_INTEL /* Recheck CMCI information after local APIC is up on CPU #0 */ - if (smp_processor_id() == 0) + if (!cpu) cmci_recheck(); #endif } |