net: add per-cpu storage and net->core_stats

Before adding yet another possibly contended atomic_long_t,
it is time to add per-cpu storage for existing ones:
 dev->tx_dropped, dev->rx_dropped, and dev->rx_nohandler

Because many devices do not have to increment such counters,
allocate the per-cpu storage on demand, so that dev_get_stats()
does not have to spend considerable time folding zero counters.

Note that some drivers have abused these counters which
were supposed to be only used by core networking stack.

v4: should use per_cpu_ptr() in dev_get_stats() (Jakub)
v3: added a READ_ONCE() in netdev_core_stats_alloc() (Paolo)
v2: add a missing include (reported by kernel test robot <[email protected]>)
    Change in netdev_core_stats_alloc() (Jakub)

Signed-off-by: Eric Dumazet <[email protected]>
Cc: jeffreyji <[email protected]>
Reviewed-by: Brian Vazquez <[email protected]>
Reviewed-by: Jakub Kicinski <[email protected]>
Acked-by: Paolo Abeni <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

0 files changed, 0 insertions, 0 deletions