On Mon, Nov 16 2020 at 13:17, Peter Zijlstra wrote:

On Fri, Nov 13, 2020 at 03:02:17PM +0100, Thomas Gleixner wrote:

quoted

-#define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
-				 | NMI_MASK))
+#define irq_count()	(nmi_count() | hardirq_count() | softirq_count())

quoted

+#define in_task()		(!(in_nmi() | in_hardirq() | in_serving_softirq()))
-#define in_task()		(!(preempt_count() & \
-				   (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))

How horrible is the code-gen? Because preempt_count() is
raw_cpu_read_4() and at least some old compilers will refuse to CSE it
(consider the this_cpu_read_stable mess).

I looked at gcc8 and 10 output and the compilers are smart enough to
fold it for the !RT case. But yeah ...

Thanks,

        tglx



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