Re: [PATCH] net: make netdev_wait_allrefs wake-able

From: Francesco Ruggeri
Date: Thu Sep 17 2020 - 02:33:43 EST


> static inline void dev_put(struct net_device *dev)
> {
> + struct task_struct *destroy_task = dev->destroy_task;
> +
> this_cpu_dec(*dev->pcpu_refcnt);
> + if (destroy_task)
> + wake_up_process(destroy_task);
> }

I just realized that this introduces a race, if dev_put drops the last
reference, an already running netdev_wait_allrefs runs to completion
and then dev_put tries to wake it up.
Any suggestions on how to avoid this without resorting to
locking?

Thanks,
Francesco