On Thu, 2013-03-14 at 00:25 -0700, Michel Lespinasse wrote: > On Wed, Mar 13, 2013 at 6:12 PM, Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> wrote: > > On Wed, 2013-03-13 at 04:36 -0700, Michel Lespinasse wrote: > >> Have you considered building your ldlock based on lib/rwsem-spinlock.c > >> instead ? i.e. having an internal spinlock to protect the ldisc > >> reference count and the reader and writer queues. This would seem much > >> simpler get right. The downside would be that a spinlock would be > >> taken for a short time whenever an ldisc reference is taken or > >> released. I don't expect that the internal spinlock would get > >> significant contention ? > > > > That would have been too easy :) > > > > TBH, I hadn't considered it until I was most the way through a working > > atomic version. I had already split the reader/writer wait lists. And > > figured out how to always use the wait bias for every waiting reader and > > writer -- rather than the rwsem way of testing for an empty list -- > > which made the timeout handling easier. > > > > At the time, the only thing that I was still struggling with was > > recursion, and the spinlock flavor wasn't going to fix that. So I just > > kept with the atomic flavor. > > Its not too late to run away from it and preserve your sanity (as well > as that of the next person working on the tty layer :) The long-term plan is to migrate it to lib so it won't be a maintenance burden to tty. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
