From: Sebastian Andrzej Siewior <bige...@linutronix.de> Date: Fri, 16 Jun 2017 19:23:59 +0200
> In 2004 [0] netif_rx_ni() gained a preempt_disable() section around > netif_rx() and its do_softirq() + testing for it. The do_softirq() part > is required because netif_rx() raises the softirq but does not invoke > it. The preempt_disable() is required to avoid running the BH in > parallel. > All this can be avoided be putting this into a local_bh_disable()ed > section. The local_bh_enable() part will invoke do_softirq() if > required. > > [0] Make netif_rx_ni preempt-safe > http://oss.sgi.com/projects/netdev/archive/2004-10/msg02211.html > > Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de> Why make extra work? The current code is cheaper. Doing all of that dance with the local_bh_enable() function call is more expensive than the inlined counter bump and softirq state check. I'm not applying this without a better justification, sorry.
