Messages in this thread | | | Date | Sat, 3 Sep 2011 13:35:22 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH -mm 1/2] irq_work, Use llist in irq_work |
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* Huang Ying (ying.huang@intel.com) wrote: > On 09/01/2011 05:57 PM, Peter Zijlstra wrote: > > On Thu, 2011-09-01 at 16:56 +0800, Huang Ying wrote: > >> Something as follow with llist_empty() seems not work. > >> > >> empty = llist_empty(irq_work_list); > >> llist_add(&work->llnode, irq_work_list); > >> if (empty) > >> arch_irq_work_raise(); > >> > >> Because irq_work IRQ handler or timer IRQ handler may be executed just > >> before "llist_add(&work->llnode, irq_work_list)", so that, although > >> "empty == false", arch_irq_work_raise() still should be executed. > > > > Right, I was thinking: > > > > llist_add(&work->llist, irq_work_list); > > if (llist_empty(&work->llist)) > > arch_irq_work_raise(); > > > > And then ran into the difference between llist_node and llist_head. Now > > we could sort that by introducing llist_next() and write it like: > > > > if (!llist_next(&work->list)) > > arch_irq_work_raise(); > > > > This reveals some implementation details of llist. But it will reveal > some implementation details to make llist_add() return whether list is > empty before adding as Mathieu pointed out. So I think something like > this or just to check work->list->next should be acceptable.
No. These solutions all appear to have some relatively high level of ugliness and expose too much of the structure internals.
I'll submit a patch to change the API from llist to llstack shortly for comments.
Thanks,
Mathieu
-- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com
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