On Fri, 2010-10-29 at 09:00 +0200, Jan Kiszka wrote: > Am 28.10.2010 21:34, Philippe Gerum wrote: > > On Thu, 2010-10-28 at 21:15 +0200, Gilles Chanteperdrix wrote: > >> Jan Kiszka wrote: > >>> Gilles, > >>> > >>> I happened to come across rthal_mark_irq_disabled/enabled on arm. On > >>> first glance, it looks like these helpers manipulate irq_desc::status > >>> non-atomically, i.e. without holding irq_desc::lock. Isn't this fragile? > >> > >> I have no idea. How do the other architectures do? As far as I know, > >> this code has been copied from there. > > > > Other archs do the same, simply because once an irq is managed by the > > hal, it may not be shared in any way with the regular kernel. So locking > > is pointless. > > Indeed, I missed that all the other archs have this uninlined in hal.c. > > However, this leaves at least a race between xnintr_disable/enable and > XN_ISR_PROPAGATE (ie. the related Linux path) behind.
I can't see why XN_ISR_PROPAGATE would be involved here. This service pends an interrupt in the pipeline log. > Not sure if it > matters practically - but risking silent breakage for this micro > optimization? It was not meant as an optimization; we may not grab the linux descriptor lock in this context because we may enter it in primary mode. > Is disabling/enabling really in the highly > latency-critical anywhere? Otherwise, I would suggest to just plug this > by adding the intended lock for this field. The caller is expected to manage locking; AFAICS the only one who does not is the RTAI skin, which is obsolete and removed in 2.6.x, so no big deal. > > Jan > -- Philippe. _______________________________________________ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
