Messages in this thread Patch in this message | | | Subject | [PATCH 1/3] smp/ipi: Remove redundant cfd->cpumask_ipi mask | From | Preeti U Murthy <> | Date | Fri, 05 Jul 2013 21:57:01 +0530 |
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cfd->cpumask_ipi is used only in smp_call_function_many().The existing comment around it says that this additional mask is used because cfd->cpumask can get overwritten.
There is no reason why the cfd->cpumask can be overwritten, since this is a per_cpu mask; nobody can change it but us and we are called with preemption disabled.
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Cc: srivatsa.bhat@linux.vnet.ibm.com Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Rusty Russell <rusty@rustcorp.com.au> ---
kernel/smp.c | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c index 4dba0f7..89be6e6 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -23,7 +23,6 @@ enum { struct call_function_data { struct call_single_data __percpu *csd; cpumask_var_t cpumask; - cpumask_var_t cpumask_ipi; }; static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data); @@ -47,9 +46,6 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, cpu_to_node(cpu))) return notifier_from_errno(-ENOMEM); - if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL, - cpu_to_node(cpu))) - return notifier_from_errno(-ENOMEM); cfd->csd = alloc_percpu(struct call_single_data); if (!cfd->csd) { free_cpumask_var(cfd->cpumask); @@ -64,7 +60,6 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) case CPU_DEAD: case CPU_DEAD_FROZEN: free_cpumask_var(cfd->cpumask); - free_cpumask_var(cfd->cpumask_ipi); free_percpu(cfd->csd); break; #endif @@ -410,13 +405,6 @@ void smp_call_function_many(const struct cpumask *mask, if (unlikely(!cpumask_weight(cfd->cpumask))) return; - /* - * After we put an entry into the list, cfd->cpumask may be cleared - * again when another CPU sends another IPI for a SMP function call, so - * cfd->cpumask will be zero. - */ - cpumask_copy(cfd->cpumask_ipi, cfd->cpumask); - for_each_cpu(cpu, cfd->cpumask) { struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu); struct call_single_queue *dst = @@ -433,7 +421,7 @@ void smp_call_function_many(const struct cpumask *mask, } /* Send a message to all CPUs in the map */ - arch_send_call_function_ipi_mask(cfd->cpumask_ipi); + arch_send_call_function_ipi_mask(cfd->cpumask); if (wait) { for_each_cpu(cpu, cfd->cpumask) {
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