On Thu, Sep 12, 2013 at 12:07:05AM +0800, Jiang Liu wrote:
> From: Jiang Liu <jiang....@huawei.com>
>
> Commit f44310b98ddb7 "smp: Fix SMP function call empty cpu mask race"
> introduced field call_function_data->cpumask_ipi to resolve a race
> condition in smp_call_function_many().
>
> Later commit 9a46ad6d6df3 "smp: make smp_call_function_many() use logic
> similar to smp_call_function_single()" fixed the same issue in another
> way when optimizing smp_call_function_many(), which then obsoletes
> changes introduced by commit f44310b98ddb7. So revert it.
>
> Signed-off-by: Jiang Liu <jiang....@huawei.com>
> Acked-by: Wang YanQing <udkni...@gmail.com>
> Cc: Jiang Liu <liu...@gmail.com>
> ---
> kernel/smp.c | 16 ++--------------
> 1 file changed, 2 insertions(+), 14 deletions(-)
>
> diff --git a/kernel/smp.c b/kernel/smp.c
> index fe9f773..a034712 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
> @@ -255,9 +250,9 @@ int smp_call_function_single(int cpu, smp_call_func_t
> func, void *info,
> csd = &__get_cpu_var(csd_data);
>
> csd_lock(csd);
> -
> csd->func = func;
> csd->info = info;
> +
> generic_exec_single(cpu, csd, wait);
> } else {
> err = -ENXIO; /* CPU not online */
> @@ -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) {
> --
> 1.8.1.2
Hi Liu and all
Commit 60c323699bb308404dcb60e8808531e02651578a
(kernel/smp.c: free related resources when failure occurs in hotplug_cfd())
is a fix patch for commit you revert, and it had been merged into mainline.
So could you ajust your patch to revert it together? I don't think we need
a separate patch to revert 60c323699bb308404dcb60e8808531e02651578a, because
your patch haven't be merged.
Thanks.
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