Hi Ming
On 3/19/19 3:58 PM, Ming Lei wrote:
> On Tue, Mar 19, 2019 at 01:17:31PM +0800, jianchao.wang wrote:
>> Hi Ming
>>
>> On 3/19/19 12:24 PM, Ming Lei wrote:
>>> @@ -591,6 +591,15 @@ EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);
>>> void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
>>> unsigned int cpu)
>>> {
>>> + /*
>>> + * Once the clear bit is set, it will be visible to allocation
>>> + * side.
>>> + *
>>> + * This memory barrier orders any READ/WRITE on the to-be-freed
>>> + * asssociated instance for avoiding potential use-after-free, and
>>> + * its pair is the memory barrier implied in sbitmap_get().
>> which one ?
>
> test_and_set_bit_lock() in __sbitmap_get_word().
Yes, thanks for your pointing out.
Would you perhaps detail this in the comment ?
Thanks
Jianchao
>
>>
>>> + */
>>> + smp_mb();
>>
>> smp_mb_before_atomic should be enough.
>
> Right, will change to it in V2.
>
> Thanks,
> Ming
>
