On 2019-04-05 10:02:45 [+0100], Julien Grall wrote: > RT folks already saw this corruption because local_bh_disable() does not > preempt on RT. They are carrying a patch (see "arm64: fpsimd: use > preemp_disable in addition to local_bh_disable()") to disable preemption > along with local_bh_disable(). > > Alternatively, Julia suggested to introduce a per-cpu lock to protect the > state. I am thinking to defer this for a follow-up patch. The changes in > this patch should make it easier because we now have helper to mark the > critical section. A per-CPU lock? It has to be a raw_spinlock_t because a normal spin_lock() / local_lock() would allow scheduling and might be taken as part of the context switch or soon after. Sebastian
