On 3/28/21 8:02 PM, Keith Busch wrote:
> On Sun, Mar 28, 2021 at 10:23:37PM -0400, Yufen Yu wrote:
>> static struct bio *__bio_chain_endio(struct bio *bio)
>> {
>> struct bio *parent = bio->bi_private;
>> + unsigned long flags;
>>
>> + spin_lock_irqsave(&parent->bi_lock, flags);
>> if (!parent->bi_status)
>> parent->bi_status = bio->bi_status;
>> + spin_unlock_irqrestore(&parent->bi_lock, flags);
>
>
> I don't see a spin_lock_init() on this new lock, though a spinlock seems
> overkill here. If you need an atomic update, you could do:
>
> cmpxchg(&parent->bi_status, 0, bio->bi_status);
Hmm ... isn't cmpxchg() significantly slower than a spinlock?
Thanks,
Bart.
