Hi Gautham-
Gautham R Shenoy wrote:
> Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
> get_online_cpus and put_online_cpus instead as it highlights
> the refcount semantics in these operations.
Something other than "get_online_cpus", please? lock_cpu_hotplug()
protects cpu_present_map as well as cpu_online_map. For example, some
of the powerpc code modified in this patch is made a bit less clear
because it is manipulating cpu_present_map, not cpu_online_map.
> Index: linux-2.6.23/arch/powerpc/platforms/pseries/hotplug-cpu.c
> ===================================================================
> --- linux-2.6.23.orig/arch/powerpc/platforms/pseries/hotplug-cpu.c
> +++ linux-2.6.23/arch/powerpc/platforms/pseries/hotplug-cpu.c
> @@ -151,7 +151,7 @@ static int pseries_add_processor(struct
> for (i = 0; i < nthreads; i++)
> cpu_set(i, tmp);
>
> - lock_cpu_hotplug();
> + get_online_cpus();
>
> BUG_ON(!cpus_subset(cpu_present_map, cpu_possible_map));
>
> @@ -188,7 +188,7 @@ static int pseries_add_processor(struct
> }
> err = 0;
> out_unlock:
> - unlock_cpu_hotplug();
> + put_online_cpus();
> return err;
> }
>
> @@ -209,7 +209,7 @@ static void pseries_remove_processor(str
>
> nthreads = len / sizeof(u32);
>
> - lock_cpu_hotplug();
> + get_online_cpus();
> for (i = 0; i < nthreads; i++) {
> for_each_present_cpu(cpu) {
> if (get_hard_smp_processor_id(cpu) != intserv[i])
> @@ -223,7 +223,7 @@ static void pseries_remove_processor(str
> printk(KERN_WARNING "Could not find cpu to remove "
> "with physical id 0x%x\n", intserv[i]);
> }
> - unlock_cpu_hotplug();
> + put_online_cpus();
> }
-
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