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| author | Eric Dumazet <edumazet@google.com> | 2022-06-08 19:04:38 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-06-10 07:53:57 +0300 |
| commit | fd9ea57f4e9514f9d0f0dec505eefd99a8faa148 (patch) | |
| tree | 78722b3552044be2170fe2330968b9e7a8251f97 /net/core/dev.c | |
| parent | ee2640df2393141a2975af726802b349d51713be (diff) | |
| download | linux-fd9ea57f4e9514f9d0f0dec505eefd99a8faa148.tar.xz | |
net: add napi_get_frags_check() helper
This is a follow up of commit 3226b158e67c
("net: avoid 32 x truesize under-estimation for tiny skbs")
When/if we increase MAX_SKB_FRAGS, we better make sure
the old bug will not come back.
Adding a check in napi_get_frags() would be costly,
even if using DEBUG_NET_WARN_ON_ONCE().
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core/dev.c')
| -rw-r--r-- | net/core/dev.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 39cb9055da37..8958c4227b67 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6351,6 +6351,23 @@ int dev_set_threaded(struct net_device *dev, bool threaded) } EXPORT_SYMBOL(dev_set_threaded); +/* Double check that napi_get_frags() allocates skbs with + * skb->head being backed by slab, not a page fragment. + * This is to make sure bug fixed in 3226b158e67c + * ("net: avoid 32 x truesize under-estimation for tiny skbs") + * does not accidentally come back. + */ +static void napi_get_frags_check(struct napi_struct *napi) +{ + struct sk_buff *skb; + + local_bh_disable(); + skb = napi_get_frags(napi); + WARN_ON_ONCE(skb && skb->head_frag); + napi_free_frags(napi); + local_bh_enable(); +} + void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi, int (*poll)(struct napi_struct *, int), int weight) { @@ -6378,6 +6395,7 @@ void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi, set_bit(NAPI_STATE_NPSVC, &napi->state); list_add_rcu(&napi->dev_list, &dev->napi_list); napi_hash_add(napi); + napi_get_frags_check(napi); /* Create kthread for this napi if dev->threaded is set. * Clear dev->threaded if kthread creation failed so that * threaded mode will not be enabled in napi_enable(). |