Messages in this thread | | | Date | Fri, 26 Aug 2011 10:21:04 -0400 | From | Don Zickus <> | Subject | Re: [V3][PATCH 2/6] x86, nmi: create new NMI handler routines |
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On Fri, Aug 26, 2011 at 11:44:12AM +0200, Peter Zijlstra wrote: > On Thu, 2011-08-25 at 12:45 -0400, Don Zickus wrote: > > +static int __setup_nmi(unsigned int type, struct nmiaction *action) > > +{ > > + struct nmi_desc *desc = nmi_to_desc(type); > > + struct nmiaction **a = &(desc->head); > > + unsigned long flags; > > + > > + spin_lock_irqsave(&desc->lock, flags); > > + > > + /* > > + * some handlers need to be executed first otherwise a fake > > + * event confuses some handlers (kdump uses this flag) > > + */ > > + if (!(action->flags & NMI_FLAG_FIRST)) > > + while ((*a) != NULL) > > + a = &((*a)->next); > > + > > + action->next = *a; > > + rcu_assign_pointer(*a, action); > > + > > + spin_unlock_irqrestore(&desc->lock, flags); > > + return 0; > > +} > > + > > +static struct nmiaction *__free_nmi(unsigned int type, const char *name) > > +{ > > + struct nmi_desc *desc = nmi_to_desc(type); > > + struct nmiaction *n, **np = &(desc->head); > > + unsigned long flags; > > + > > + spin_lock_irqsave(&desc->lock, flags); > > + > > + while ((*np) != NULL) { > > + n = *np; > > + > > + /* > > + * the name passed in to describe the nmi handler > > + * is used as the lookup key > > + */ > > + if (!strcmp(n->name, name)) { > > + WARN(in_nmi(), > > + "Trying to free NMI (%s) from NMI context!\n", n->name); > > + rcu_assign_pointer(*np, n->next); > > + break; > > + } > > + np = &(n->next); > > + } > > + > > + spin_unlock_irqrestore(&desc->lock, flags); > > + synchronize_rcu(); > > + return (*np); > > +} > > Probably not worth fixing, but if someone was silly enough to register > with an already existing name we're up shit creek, right? :-)
Hmm, I thought I put a check in there during registration to prevent that. Guess not. But yeah, I thought about doing that just to have one less thing bite me later.
Cheers, Don
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