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We allow drivers to call napi_hash_del() before calling netif_napi_del() to batch RCU grace periods. This makes the API asymmetric and leaks internal implementation details. Soon we will want the grace period to protect more than just the NAPI hash table. Restructure the API and have drivers call a new function - __netif_napi_del() if they want to take care of RCU waits. Note that only core was checking the return status from napi_hash_del() so the new helper does not report if the NAPI was actually deleted. Some notes on driver oddness: - veth observed the grace period before calling netif_napi_del() but that should not matter - myri10ge observed normal RCU flavor - bnx2x and enic did not actually observe the grace period (unless they did so implicitly) - virtio_net and enic only unhashed Rx NAPIs The last two points seem to indicate that the calls to napi_hash_del() were a left over rather than an optimization. Regardless, it's easy enough to correct them. This patch may introduce extra synchronize_net() calls for interfaces which set NAPI_STATE_NO_BUSY_POLL and depend on free_netdev() to call netif_napi_del(). This seems inevitable since we want to use RCU for netpoll dev->napi_list traversal, and almost no drivers set IFF_DISABLE_NETPOLL. Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> |
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