On Sat, 14 Jan 2012 13:12:07 +0100, Daniel Vetter <dan...@ffwll.ch> wrote:
> I think that race is air-tight with your patch to rework the reset code > already. But better safe than sorry. And as I've said a good cleanup > anyway. Sounds good. I like clearer code, especially when it doesn't cost performance. I think I'd like my version in -fixes so that we don't change anything with -next; no reason to have two slightly different versions out there in case one (or the other) is broken? > One of the reasons Chris originally shot down Ben's forcewake patches > which protected everything with a spinlock (i.e. also writes) is the > overhead. And writes to advance the ring are actually rather common. Iirc > Chris even wrote a patch to cut down on the overhead by caching the fifo > count. So I think we actually want this asymmetry in locking for > performance reasons. Ah, that's a good reason to use different locking for each path then. Suitable documentation, and a WARN_ON in the write path to check for the struct_mutex should suffice to prevent mistakes in the future. -- keith.pack...@intel.com
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