Re: [PATCH w-t] iwlwifi: rewrite iwl-scan.c to avoid race conditions

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2010-09-01 at 13:58 +0200, Stanislaw Gruszka wrote:

> Custom workqueue is not strictly needed, but it assure all works will
> run short after schedule. Common workqueue can not give us such guarantees,
> as other driver/subsystem can schedule own work, possibly slow, which
> can block start of our work for long time.

I believe that's no longer true, with Tejun's workqueue rewrite that
just got into mainline.

> > Shouldn't that only be a few of them anyway?
> 
> For sure abort_scan and abort_timeout works have to be scheduled on something
> other than priv->workqueue. I'm queuing all scan works on priv->scan_workqueue
> for consistency.

Remind me: The reason is that we need to cancel them from within the
workqueue? But if we're on the same workqueue, it seems like they
couldn't be running already, so cancel_work_sync() would always cancel
them? Do we get lockdep errors for that? Or are there actual locks
involved?

johannes