net: add CONFIG_PCPU_DEV_REFCNT
I was working on a syzbot issue, claiming one device could not be dismantled because its refcount was -1 unregister_netdevice: waiting for sit0 to become free. Usage count = -1 It would be nice if syzbot could trigger a warning at the time this reference count became negative. This patch adds CONFIG_PCPU_DEV_REFCNT options which defaults to per cpu variables (as before this patch) on SMP builds. v2: free_dev label in alloc_netdev_mqs() is moved to avoid a compiler warning (-Wunused-label), as reported by kernel test robot <lkp@intel.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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