On 03/04/2017 09:01 AM, Paolo Valente wrote:
> @@ -560,6 +600,15 @@ struct bfq_data {
> struct bfq_io_cq *bio_bic;
> /* bfqq associated with the task issuing current bio for merging */
> struct bfq_queue *bio_bfqq;
> +
> + /*
> + * io context to put right after bfqd->lock is released. This
> + * filed is used to perform put_io_context, when needed, to
> + * after the scheduler lock has been released, and thus
> + * prevent an ioc->lock from being possibly taken while the
> + * scheduler lock is being held.
> + */
> + struct io_context *ioc_to_put;
> };
The logic around this is nasty, effectively you end up having locking
around sections of code instea of structures, which is never a good
idea.
The helper functions for unlocking and dropping the ioc add to the mess
as well.
Can't we simply pass back a pointer to an ioc to free? That should be
possible, given that we must have grabbed the bfqd lock ourselves
further up in the call chain. So we _know_ that we'll drop it later on.
If that wasn't the case, the existing logic wouldn't work.
--
Jens Axboe
