On Sat, Sep 14, 2013 at 12:41:36PM +0800, Wang YanQing wrote:
> On Thu, Sep 12, 2013 at 12:07:05AM +0800, Jiang Liu wrote:
> > From: Jiang Liu <jiang.liu@xxxxxxxxxx>
> >
> > 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.liu@xxxxxxxxxx>
> > Acked-by: Wang YanQing <udknight@xxxxxxxxx>
> > Cc: Jiang Liu <liuj97@xxxxxxxxx>
> > ---
> > 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.
Add Cc:gang.chen@xxxxxxxxxxx
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