Messages in this thread | | | From | Yong Zhang <> | Subject | [RFC PATCH 00/10] Cleanup ipi_call_lock[_irq]()/ipi_call_unlock[_irq]() | Date | Tue, 29 May 2012 15:15:55 +0800 |
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As discussed with Srivatsa [1], it seems there is no need to keep ipi_call_[un]lock_irq() when cpu bring-up/down. Because:
1) call_function.lock used in smp_call_function_many() is just to protect call_function.queue and &data->refs, cpu_online_mask is outside of the lock. And it's not necessary to protect cpu_online_mask, because data->cpumask is pre-calculate and even if a cpu is brougt up when calling arch_send_call_function_ipi_mask(), it's harmless because validation test in generic_smp_call_function_interrupt() will take care of it.
2) For cpu down issue, stop_machine() will guarantee that no concurrent smp_call_fuction() is processing.
In short it's more likely that keeping ipi_call_[un]lock() is leftover before we introduce generic smp helper. This patchset is just to clean things up.
[1] http://marc.info/?l=linux-kernel&m=133766786814484&w=2
Yong Zhang (10): hexagon: smp: remove call to ipi_call_lock()/ipi_call_unlock() mn10300: smp: remove call to ipi_call_lock()/ipi_call_unlock() parisc: smp: remove call to ipi_call_lock()/ipi_call_unlock() S390: smp: remove call to ipi_call_lock()/ipi_call_unlock() tile: smp: remove call to ipi_call_lock()/ipi_call_unlock() x86: smp: remove call to ipi_call_lock()/ipi_call_unlock() ia64: smp: remove call to ipi_call_lock_irq()/ipi_call_unlock_irq() SPARC: smp: remove call to ipi_call_lock_irq()/ipi_call_unlock_irq() POWERPC: smp: remove call to ipi_call_lock()/ipi_call_unlock() smp: remove ipi_call_lock[_irq]()/ipi_call_unlock[_irq]()
arch/hexagon/kernel/smp.c | 2 -- arch/ia64/kernel/smpboot.c | 2 -- arch/mn10300/kernel/smp.c | 2 -- arch/parisc/kernel/smp.c | 2 -- arch/powerpc/kernel/smp.c | 2 -- arch/s390/kernel/smp.c | 2 -- arch/sparc/kernel/smp_64.c | 6 ++---- arch/tile/kernel/smpboot.c | 10 ---------- arch/x86/kernel/smpboot.c | 9 --------- arch/x86/xen/smp.c | 2 -- include/linux/smp.h | 4 ---- kernel/smp.c | 20 -------------------- 12 files changed, 2 insertions(+), 61 deletions(-)
-- 1.7.5.4
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