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| author |   Jakub Kicinski <kuba@kernel.org> | 2020-09-09 10:37:52 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2020-09-10 13:08:46 -0700 |
| commit | 4d092dd2041a5f328410ad16d63b8606c24e8604 (patch) | |
| tree | 453786a03afc9e7c8cfa8cf37af80ee023fb50d0 /net/core | |
| parent | net: remove napi_hash_del() from driver-facing API (diff) | |
| download | linux-dev-4d092dd2041a5f328410ad16d63b8606c24e8604.tar.xz linux-dev-4d092dd2041a5f328410ad16d63b8606c24e8604.zip | |
net: manage napi add/del idempotence explicitly
To RCUify napi->dev_list we need to replace list_del_init()
with list_del_rcu(). There is no _init() version for RCU for
obvious reasons. Up until now netif_napi_del() was idempotent
so to make sure it remains such add a bit which is set when
NAPI is listed, and cleared when it removed. Since we don't
expect multiple calls to netif_napi_add() to be correct,
add a warning on that side.
Now that napi_hash_add / napi_hash_del are only called by
napi_add / del we can actually steal its bit. We just need
to make sure hash node is initialized correctly.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/dev.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 205b7339d4ae..e0a1be986824 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6533,8 +6533,7 @@ EXPORT_SYMBOL(napi_busy_loop); static void napi_hash_add(struct napi_struct *napi) { - if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state) || - test_and_set_bit(NAPI_STATE_HASHED, &napi->state)) + if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state)) return; spin_lock(&napi_hash_lock); @@ -6559,8 +6558,7 @@ static void napi_hash_del(struct napi_struct *napi) { spin_lock(&napi_hash_lock); - if (test_and_clear_bit(NAPI_STATE_HASHED, &napi->state)) - hlist_del_rcu(&napi->napi_hash_node); + hlist_del_init_rcu(&napi->napi_hash_node); spin_unlock(&napi_hash_lock); } @@ -6595,7 +6593,11 @@ static void init_gro_hash(struct napi_struct *napi) void netif_napi_add(struct net_device *dev, struct napi_struct *napi, int (*poll)(struct napi_struct *, int), int weight) { + if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state))) + return; + INIT_LIST_HEAD(&napi->poll_list); + INIT_HLIST_NODE(&napi->napi_hash_node); hrtimer_init(&napi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED); napi->timer.function = napi_watchdog; init_gro_hash(napi); @@ -6650,6 +6652,9 @@ static void flush_gro_hash(struct napi_struct *napi) /* Must be called in process context */ void __netif_napi_del(struct napi_struct *napi) { + if (!test_and_clear_bit(NAPI_STATE_LISTED, &napi->state)) + return; + napi_hash_del(napi); list_del_init(&napi->dev_list); napi_free_frags(napi); |