Messages in this thread | | | Subject | Re: [PATCH v5 3.1.0-rc4-tip 18/26] uprobes: slot allocation. | From | Peter Zijlstra <> | Date | Tue, 27 Sep 2011 14:55:23 +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; > +}
> +static void xol_free_insn_slot(struct task_struct *tsk) > +{ > + struct uprobes_xol_area *area; > + unsigned long vma_end; > + unsigned long slot_addr; > + > + if (!tsk->mm || !tsk->mm->uprobes_xol_area || !tsk->utask) > + return; > + > + slot_addr = tsk->utask->xol_vaddr; > + > + if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr))) > + return; > + > + area = tsk->mm->uprobes_xol_area; > + vma_end = area->vaddr + PAGE_SIZE; > + if (area->vaddr <= slot_addr && slot_addr < vma_end) { > + int slot_nr; > + unsigned long offset = slot_addr - area->vaddr; > + unsigned long flags; > + > + slot_nr = offset / UPROBES_XOL_SLOT_BYTES; > + if (slot_nr >= UINSNS_PER_PAGE) > + return; > + > + spin_lock_irqsave(&area->slot_lock, flags); > + __clear_bit(slot_nr, area->bitmap); > + spin_unlock_irqrestore(&area->slot_lock, flags); > + atomic_dec(&area->slot_count); > + if (waitqueue_active(&area->wq)) > + wake_up(&area->wq); > + tsk->utask->xol_vaddr = 0; > + } > +}
So if you want to keep that slot_lock, you might as well make ->slot_count a normal integer.
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