Hello,
On Mon, Oct 29, 2012 at 05:01:36PM +0800, Aaron Lu wrote:
> ODD_suspend disk_events_workfn
> ata_port_suspend check_events
> disk_block_events resume ODD
> cancel_delayed_work_sync resume parent
> (waiting for disk_events_workfn) (waiting for suspend callback)
I don't understand why solving it needs to be this elaborate.
check_event() can retry. Just add a per-sr mutex which is try-locked
by sr_block_check_events() and grab it when entering zero power.
> +/*
> + * Under some circumstances, there is a race between the calling thread
> + * of disk_block_events and the events checking function. To avoid such a race,
> + * this function will check if the delayed work is pending. If not, it means
> + * the work is either not queued or is already running, false is returned.
> + * And if yes, try to cancel the delayed work. If succedded, disk_block_events
> + * will be called and there is no worry that cancel_delayed_work_sync will
> + * deadlock the events checking function. And if failed, false is returned.
> + */
> +bool disk_try_block_events(struct gendisk *disk)
> +{
> + struct disk_events *ev = disk->ev;
> +
> + if (!ev)
> + return false;
> +
> + if (delayed_work_pending(&ev->dwork)) {
And please don't use delayed_work_pending() like this. It doesn't add
anything. cancel_delayed_work() already needs to perform all the
necessary tests.
> + if (cancel_delayed_work(&disk->ev->dwork)) {
> + disk_block_events(disk);
> + return true;
> + }
> + }
> +
> + return false;
> +}
Thanks.
--
tejun
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