Long used destructors kfree_skb and kfree_skb_reason do not pass
receiving socket to packet drop tracepoints trace_kfree_skb.
This makes it hard to track packet drops of a certain netns (container)
or a socket (user application).
The naming of these destructors are also not consistent with most sk/skb
operating functions, i.e. functions named "sk_xxx" or "skb_xxx".
Introduce a new functions sk_skb_reason_drop as drop-in replacement for
kfree_skb_reason on local receiving path. Callers can now pass receiving
sockets to the tracepoints.
kfree_skb and kfree_skb_reason are still usable but they are now just
inline helpers that call sk_skb_reason_drop.
Note it is not feasible to do the same to consume_skb. Packets not
dropped can flow through multiple receive handlers, and have multiple
receiving sockets. Leave it untouched for now.
Suggested-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: Yan Zhai <y...@cloudflare.com>
---
v1->v2: changes function names to be more consistent with common sk/skb
operations
---
include/linux/skbuff.h | 10 ++++++++--
net/core/skbuff.c | 22 ++++++++++++----------
2 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index fe7d8dbef77e..c479a2515a62 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1251,8 +1251,14 @@ static inline bool skb_data_unref(const struct sk_buff
*skb,
return true;
}
-void __fix_address
-kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason);
+void __fix_address sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb,
+ enum skb_drop_reason reason);
+
+static inline void
+kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
+{
+ sk_skb_reason_drop(NULL, skb, reason);
+}
/**
* kfree_skb - free an sk_buff with 'NOT_SPECIFIED' reason
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 2854afdd713f..9def11fe42c4 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1190,7 +1190,8 @@ void __kfree_skb(struct sk_buff *skb)
EXPORT_SYMBOL(__kfree_skb);
static __always_inline
-bool __kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
+bool __sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb,
+ enum skb_drop_reason reason)
{
if (unlikely(!skb_unref(skb)))
return false;
@@ -1203,26 +1204,27 @@ bool __kfree_skb_reason(struct sk_buff *skb, enum
skb_drop_reason reason)
if (reason == SKB_CONSUMED)
trace_consume_skb(skb, __builtin_return_address(0));
else
- trace_kfree_skb(skb, __builtin_return_address(0), reason, NULL);
+ trace_kfree_skb(skb, __builtin_return_address(0), reason, sk);
return true;
}
/**
- * kfree_skb_reason - free an sk_buff with special reason
+ * sk_skb_reason_drop - free an sk_buff with special reason
+ * @sk: the socket to receive @skb, or NULL if not applicable
* @skb: buffer to free
* @reason: reason why this skb is dropped
*
- * Drop a reference to the buffer and free it if the usage count has
- * hit zero. Meanwhile, pass the drop reason to 'kfree_skb'
- * tracepoint.
+ * Drop a reference to the buffer and free it if the usage count has hit
+ * zero. Meanwhile, pass the receiving socket and drop reason to
+ * 'kfree_skb' tracepoint.
*/
void __fix_address
-kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
+sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb, enum skb_drop_reason
reason)
{
- if (__kfree_skb_reason(skb, reason))
+ if (__sk_skb_reason_drop(sk, skb, reason))
__kfree_skb(skb);
}
-EXPORT_SYMBOL(kfree_skb_reason);
+EXPORT_SYMBOL(sk_skb_reason_drop);
#define KFREE_SKB_BULK_SIZE 16
@@ -1261,7 +1263,7 @@ kfree_skb_list_reason(struct sk_buff *segs, enum
skb_drop_reason reason)
while (segs) {
struct sk_buff *next = segs->next;
- if (__kfree_skb_reason(segs, reason)) {
+ if (__sk_skb_reason_drop(NULL, segs, reason)) {
skb_poison_list(segs);
kfree_skb_add_bulk(segs, &sa, reason);
}
--
2.30.2
