> >
> > if (current->used_math) { /* Using the FPU again.
> */
> > lazy_fpu_switch(last_task_used_math);
> > } else { /* First time FPU user.
> */
> > init_fpu();
> > current->used_math = 1;
> > }
> > last_task_used_math = current;
> >
> > Clearly the second path is logically the correct one.
>
> Not really. See below.
>
> > BTW, do I see another bug here in do_cpu()? It seems that before we
call
> > init_fpu(), we should check last_task_used_math. If it is not NULL, we
> should
> > save the FP state to the last_task_used_math. Hmm, strange ...
>
> Strange indeed. And note that if the code were correct, your
> surmise about the init_fpu() path being "logically the correct"
> one would no longer be true - we'd be saving the FPU state of
> the current process for no good reason.
And note further that, by forcing current->used_math to
zero, the old code was in fact driving the signal handler
needlessly into the broken code...
Kevin K.
