On 01/29/2015 04:08 PM, Oleg Nesterov wrote: > unlazy_fpu()->__thread_fpu_end() doesn't look right if use_eager_fpu(). > Unconditional __thread_fpu_end() is only correct if we know that this > thread can't return to user-mode and use FPU. > > Fortunately it has only 2 callers. fpu_copy() checks use_eager_fpu(), > and init_fpu(current) can be only called by the coredumping thread via > regset->get(). But it is exported to modules, and imo this should be > fixed anyway. > > And if we check use_eager_fpu() we can use __save_fpu() like fpu_copy() > and save_init_fpu() do. > > - It seems that even !use_eager_fpu() case doesn't need the unconditional > __thread_fpu_end(), we only need it if __save_init_fpu() returns 0. > > - It is still not clear to me if __save_init_fpu() can safely nest with > another save + restore from __kernel_fpu_begin(). If not, we can use > kernel_fpu_disable() to fix the race. > > Signed-off-by: Oleg Nesterov <o...@redhat.com>
Reviewed-by: Rik van Riel <r...@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
