Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH] firmware loader: don't cancel _nowait requests when helper is not yet available | Date | Thu, 15 Mar 2012 00:04:16 +0100 |
| |
On Wednesday, March 14, 2012, Stephen Boyd wrote: > On 03/13/12 13:14, Rafael J. Wysocki wrote: > > All of those use cases are in fact of the "wait for user space to be thawed > > and then load the firmware" type, which I believe may be handled without > > changing that code. > > > > Why don't you make your kthread freezable, for one example? > > > > Why don't you use a freezable workqueue instead? > > > > If we put it on the freezable workqueue or make it a freezable thread > will it work?
That depends on what exactly you want to achieve, which isn't entirely clear to me at this point.
> In my scenario a wakeup interrupt comes in that wakes us up from > suspend. Within that wakeup handler a work item is scheduled to the > freezable workqueue. That work item then calls request_firmware().
That should work.
> It looks like we call schedule() after thawing the workqueues and tasks > so the work item could run before usermodehelpers are enabled and then > request_firmware() would fail. Do we need something like this (ignore > the fact that we call usermodhelper_enable() twice)? > > diff --git a/kernel/power/process.c b/kernel/power/process.c > index 7e42645..61bfa95 100644 > --- a/kernel/power/process.c > +++ b/kernel/power/process.c > @@ -187,6 +187,7 @@ void thaw_processes(void) > } while_each_thread(g, p); > read_unlock(&tasklist_lock); > > + usermodehelper_enable();
That would be a reasonable change.
> schedule(); > printk("done.\n"); > } > > > Is there a reason we disable usermodehelpers if > CONFIG_SUSPEND_FREEZER=n?
Not really, but CONFIG_SUSPEND_FREEZER=n can only work reliably in a very limited set of cases, so I don't think it's even worth making the general code depend on it.
I'd actually prefer to remove CONFIG_SUSPEND_FREEZER altogether, because it's not very useful nowadays (probably isn't useful at all).
> Should we do this instead so that > usermodehelpers are only disabled if we freeze userspace? Also what is > that schedule() call in thaw_kernel_threads() for? It looks like we'll > call schedule between kernel thread thawing and userspace thawing.
Which is OK, I think.
> I pushed out the schedule() call to the callers so that we don't call > schedule() until userspace is thawed.
Why did you do that?
Rafael
| |