Messages in this thread | | | Date | Fri, 02 Sep 2011 09:14:26 +0800 | From | Huang Ying <> | Subject | Re: [PATCH -mm 1/2] irq_work, Use llist in irq_work |
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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.
Best Regards, Huang Ying
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