Re: [PATCH RFC] r8152: Ensure that napi_schedule() is handled

On Fri, 14 May 2021 12:17:19 +0200 Thomas Gleixner wrote:

The driver invokes napi_schedule() in several places from task
context. napi_schedule() raises the NET_RX softirq bit and relies on the
calling context to ensure that the softirq is handled. That's usually on
return from interrupt or on the outermost local_bh_enable().

But that's not the case here which causes the soft interrupt handling to be
delayed to the next interrupt or local_bh_enable(). If the task in which
context this is invoked is the last runnable task on a CPU and the CPU goes
idle before an interrupt arrives or a local_bh_disable/enable() pair
handles the pending soft interrupt then the NOHZ idle code emits the
following warning.

  NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!

Prevent this by wrapping the napi_schedule() invocation from task context
into a local_bh_disable/enable() pair.

I should have read through my inbox before replying :)

I'd go for switching to raise_softirq_irqoff() in ____napi_schedule()...
why not?