On Mon, Oct 12, 2009 at 11:24 AM, Joel Fernandes <[email protected]> wrote: > Hi Friends, > > I have a question about tasklets: > > I understand that they are used to defer work during interrupt > handling. What I don't understand is - how do they handle queuing of > deferred work? > Specially with tasklets, if a tasklet is re-scheduled before the > previous scheduling of the same tasklet has a chance to run, then the > tasklet is executed only once - not twice. But what if the work that > the tasklet was supposed to do in these 2 instances were different and > that its function was supposed to be passed 2 different structures? > Shouldn't the tasklet be executed twice with these 2 structures? > > I know that work queues are there for that, but how do device drivers > that use tasklets cope with the above?
One thing that I can suggest is to pass those data structures as linked list together with something like "already_done" flag. So, if a tasklest is already done with single data, mark it, then move onto next data. It would be better to use atomic_t as flag's type, since IMO there is a chance a race condition happen to toggle this flag. Alternative:use head pointer to mark next data target. Again, setting head pointer should be done atomically. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ
