Andy Lutomirski <l...@kernel.org> writes: > On Fri, May 15, 2020 at 5:10 PM Thomas Gleixner <t...@linutronix.de> wrote: >> >> >> The scheduler IPI does not need the full interrupt entry handling logic >> when the entry is from kernel mode. >> >> Even if tracing is enabled the only requirement is that RCU is watching and >> preempt_count has the hardirq bit on. >> >> The NOHZ tick state does not have to be adjusted. If the tick is not >> running then the CPU is in idle and the idle exit will restore the >> tick. Softinterrupts are not raised here, so handling them on return is not >> required either. >> >> User mode entry must go through the regular entry path as it will invoke >> the scheduler on return so context tracking needs to be in the correct >> state. >> >> Use IDTENTRY_RAW and the RCU conditional variants of idtentry_enter/exit() >> to guarantee that RCU is watching even if the IPI hits a RCU idle section. >> >> Remove the tracepoint static key conditional which is incomplete >> vs. tracing anyway because e.g. ack_APIC_irq() calls out into >> instrumentable code. >> >> Avoid the overhead of irq time accounting and introduce variants of >> __irq_enter/exit() so instrumentation observes the correct preempt count >> state. > > Leftover text from an old version?
Indeed > The code is Reviewed-by: Andy Lutomirski <l...@kernel.org>
