On Wed, Aug 13, 2014 at 07:59:06AM +0900, Tetsuo Handa wrote:
> Luis R. Rodriguez wrote:
> > Tetsuo bisected and found that commit 786235ee \"kthread: make
> > kthread_create() killable\" modified kthread_create() to bail as
> > soon as SIGKILL is received.
>
> I just wrote commit 786235ee. It is not Tetsuo who bisected it.
>
> > @@ -128,4 +129,38 @@ bool queue_kthread_work(struct kthread_worker *worker,
> > void flush_kthread_work(struct kthread_work *work);
> > void flush_kthread_worker(struct kthread_worker *worker);
> >
> > +#ifndef MODULE
> > +
> > +#define module_long_probe_init(x) __initcall(x);
> > +#define module_long_probe_exit(x) __exitcall(x);
> > +
> > +#else
> > +/* To be used by modules which can take over 30 seconds at probe */
> > +#define module_long_probe_init(initfn) \\
> > + static struct task_struct *__init_thread; \\
> > + static int _long_probe_##initfn(void *arg) \\
> > + { \\
> > + return initfn(); \\
> > + } \\
> > + static inline __init int __long_probe_##initfn(void) \\
> > + { \\
> > + __init_thread = kthread_run(_long_probe_##initfn,\\
> > + NULL, \\
> > + #initfn); \\
> > + if (IS_ERR(__init_thread)) \\
> > + return PTR_ERR(__init_thread); \\
> > + return 0; \\
> > + } \\
> > + module_init(__long_probe_##initfn);
> > +/* To be used by modules that require module_long_probe_init() */
> > +#define module_long_probe_exit(exitfn) \\
> > + static inline void __long_probe_##exitfn(void) \\
> > + { \\
> > + exitfn(); \\
>
> exitfn() must not be called if initfn() failed or has not
> completed yet. You need a bool variable for indicating that
> we are ready to call exitfn().
>
> Also, subsequent userspace operations may fail if
> we return to userspace before initfn() completes
> (e.g. device nodes are not created yet).
I doubt that this will be a problem, as device nodes are usually created
_after_ module_init() returns.
But the cleanup issues are real on error paths. Given that these
drivers will need "work" anyway, I don't think it's really a big deal.
thanks,
greg k-h
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