On 09/14/2013 12:43 PM, Wang YanQing wrote: > 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 <[email protected]> >>> >>> 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 <[email protected]> >>> Acked-by: Wang YanQing <[email protected]> >>> Cc: Jiang Liu <[email protected]> >>> --- >>> 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:[email protected]
Thank you, and, I should continue trying to familiar with kernel step by step. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- Chen Gang -- Chen Gang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
