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authorEric Dumazet <edumazet@google.com>2022-06-08 19:04:38 +0300
committerJakub Kicinski <kuba@kernel.org>2022-06-10 07:53:57 +0300
commitfd9ea57f4e9514f9d0f0dec505eefd99a8faa148 (patch)
tree78722b3552044be2170fe2330968b9e7a8251f97 /net/core/dev.c
parentee2640df2393141a2975af726802b349d51713be (diff)
downloadlinux-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.c18
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().