| Subject | Re: [PATCH v5 3.1.0-rc4-tip 18/26] uprobes: slot allocation. | From | Peter Zijlstra <> | Date | Tue, 27 Sep 2011 14:37:59 +0200 |
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On Tue, 2011-09-20 at 17:33 +0530, Srikar Dronamraju wrote: > +static unsigned long xol_take_insn_slot(struct uprobes_xol_area *area) > +{ > + unsigned long slot_addr, flags; > + int slot_nr; > + > + do { > + spin_lock_irqsave(&area->slot_lock, flags); > + slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); > + if (slot_nr < UINSNS_PER_PAGE) { > + __set_bit(slot_nr, area->bitmap); > + slot_addr = area->vaddr + > + (slot_nr * UPROBES_XOL_SLOT_BYTES); > + atomic_inc(&area->slot_count); > + } > + spin_unlock_irqrestore(&area->slot_lock, flags); > + if (slot_nr >= UINSNS_PER_PAGE) > + xol_wait_event(area); > + > + } while (slot_nr >= UINSNS_PER_PAGE); > + > + return slot_addr; > +}
Why isn't a find_first_bit() + set_and_test_bit() not sufficient? That is, what do you need that lock for?
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