On 2019-02-28 01:05:02 [+0000], Liu, Yongxin wrote:
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index 63cb01ef4ef0..0eecc8670f80 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -926,18 +926,15 @@ int nd_blk_region_init(struct nd_region *nd_region) unsigned int nd_region_acquire_lane(struct nd_region *nd_region) {
> unsigned int cpu, lane;
> + struct nd_percpu_lane *ndl_lock, *ndl_count;
>
> - cpu = get_cpu();
> - if (nd_region->num_lanes < nr_cpu_ids) {
> - struct nd_percpu_lane *ndl_lock, *ndl_count;
> + cpu = get_cpu_light();
what is wrong with using raw_smp_processor_id() instead of get_cpu()? In
case the schedulers pushes the task to another CPU the it will access
cross-CPU data which is locked.
>
> - lane = cpu % nd_region->num_lanes;
> - ndl_count = per_cpu_ptr(nd_region->lane, cpu);
> - ndl_lock = per_cpu_ptr(nd_region->lane, lane);
> - if (ndl_count->count++ == 0)
> - spin_lock(&ndl_lock->lock);
> - } else
> - lane = cpu;
> + lane = cpu % nd_region->num_lanes;
> + ndl_count = per_cpu_ptr(nd_region->lane, cpu);
> + ndl_lock = per_cpu_ptr(nd_region->lane, lane);
> + if (ndl_count->count++ == 0)
> + spin_lock(&ndl_lock->lock);
>
> return lane;
> }
Sebastian
