On 02/20, Borislav Petkov wrote: > > On Mon, Jan 19, 2015 at 07:51:09PM +0100, Oleg Nesterov wrote: > > math_state_restore() and its usage doesn't look nice. init_fpu() too, > > Yeah, about that: > > I see: > > math_state_restore > ... > if (!tsk_used_math(tsk)) > init_fpu() > > and init_fpu() then does: > > if (tsk_used_math(tsk)) >
Yes, and more. math_state_restore() assumes that it is called with irqs disabled. At least if !tsk_used_math. That is why 3/3 calls init_fpu() first. Not only this doesn't look clean, this is simply not true in general. The comment above init_fpu() is simply wrong. And unlazy_fpu() from there doesn't look nice. This mixes 2 completely differents things. > Could use a cleanup and so on... Perhaps it is in the works already :) Yes, I'll try to make the cleanups on top of these changes. And let me repeat that there is another reason for 1/3 and 2/3 at least (3/3 makes sense too), if we add TIF_LOAD_FPU we need to avoid the performance regression (irq_fpu_usable() should not fail if !__thread_has_fpu()). Oleg. -- 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/
