Hi Rajat, On Fri, Nov 15, 2013 at 8:46 PM, Rajat Jain <rajatjain@xxxxxxxxxxx> wrote: > Hi, > > I have a single work queue, on which I have scheduled a worker function [using queue_work(wq, fn)] in interrupt context. > > I get the interrupt twice before the work queue gets a chance to run, and hence the same function will get queued twice (with different private context - arguments etc) which is fine and expected. You got it wrong here. bool queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) { bool ret = false; unsigned long flags; local_irq_save(flags); if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { __queue_work(cpu, wq, work); ret = true; } local_irq_restore(flags); return ret; } EXPORT_SYMBOL(queue_work_on); If you look at function queue_work_on, the function returns immediately if WORK_STRUCT_PENDING_BIT was already set. So in effect your second call to queue_work will just return. HTH Thanks, Arun > > Questions: > > 1) Is it possible that the instance that was queued by 2nd interrupt, can get to run BEFORE the instance that was queued by 1st interrupt? In other words, is reordering possible? > > 2) Is it possible that one running instance of the function, can get preempted by second instance of the same work queue? I read through http://lwn.net/Articles/511421/ and it talks about same work queue cannot run on different CPU, but I have doubt about single CPU. If If I am writing a worker function, does my code have to be ready that it can be preempted by another instance of the same function? > > Please note that I understand that my worker function can preempted by other processes, my doubts are related to the same workqueue. > > Thanks, > > Rajat > > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs