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

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