Re: [PATCH v10 4/5] core: Add kernel message dumper to call on oopses and panics

Artem Bityutskiy
2009-10-16T11:04:00Z

On Fri, 2009-10-16 at 12:10 +0200, Ingo Molnar wrote:
> * Simon Kagstrom <simon.kagstrom@netinsight.net> wrote:
>
> > +int kmsg_dump_register(struct kmsg_dumper *dumper)
> > +{
> > + unsigned long flags;
> > +
> > + /* The dump callback needs to be set */
> > + if (!dumper->dump)
> > + return -EINVAL;
> > +
> > + spin_lock_irqsave(&dump_list_lock, flags);
> > +
> > + /* Don't allow registering multiple times */
> > + if (dumper->registered) {
> > + spin_unlock_irqrestore(&dump_list_lock, flags);
> > +
> > + return -EBUSY;
> > + }
> > +
> > + dumper->registered = 1;
> > + list_add(&dumper->list, &dump_list);
> > + spin_unlock_irqrestore(&dump_list_lock, flags);
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(kmsg_dump_register);
>
>
> i dont want to bikeshed paint this but this sequence caught my eyes. We
> generally do flatter and clearer locking sequences:
>
> int kmsg_dump_register(struct kmsg_dumper *dumper)
> {
> unsigned long flags;
> int err = -EBUSY;
>
> /* The dump callback needs to be set */
> if (!dumper->dump)
> return -EINVAL;
>
> spin_lock_irqsave(&dump_list_lock, flags);
>
> /* Don't allow registering multiple times */
> if (!dumper->registered) {
> dumper->registered = 1;
> list_add_tail(&dumper->list, &dump_list);
> err = 0;
> }
>
> spin_unlock_irqrestore(&dump_list_lock, flags);
>
> return err;
> }
> EXPORT_SYMBOL_GPL(kmsg_dump_register);

And while we are on it, I think these extra lines before and after
spinlocks are unneeded and even a bit annoying :-)

--
Best Regards,
Artem Bityutskiy (Артём Битюцкий)