diff options
| author | Menglong Dong <imagedong@tencent.com> | 2022-08-21 13:18:58 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2022-08-24 09:47:51 +0100 |
| commit | c205cc7534a97f2d6fbd2a23a94ed7c036c6e2aa (patch) | |
| tree | 3d3bef30360bef6fa79771d761fa2b1a21803eed | |
| parent | fa2bc96259098a3bc1f32a10bfe1139c0f742256 (diff) | |
net: skb: prevent the split of kfree_skb_reason() by gcc
Sometimes, gcc will optimize the function by spliting it to two or
more functions. In this case, kfree_skb_reason() is splited to
kfree_skb_reason and kfree_skb_reason.part.0. However, the
function/tracepoint trace_kfree_skb() in it needs the return address
of kfree_skb_reason().
This split makes the call chains becomes:
kfree_skb_reason() -> kfree_skb_reason.part.0 -> trace_kfree_skb()
which makes the return address that passed to trace_kfree_skb() be
kfree_skb().
Therefore, introduce '__fix_address', which is the combination of
'__noclone' and 'noinline', and apply it to kfree_skb_reason() to
prevent to from being splited or made inline.
(Is it better to simply apply '__noclone oninline' to kfree_skb_reason?
I'm thinking maybe other functions have the same problems)
Meanwhile, wrap 'skb_unref()' with 'unlikely()', as the compiler thinks
it is likely return true and splits kfree_skb_reason().
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/compiler_attributes.h | 7 | ||||
| -rw-r--r-- | include/linux/skbuff.h | 3 | ||||
| -rw-r--r-- | net/core/skbuff.c | 5 |
3 files changed, 12 insertions, 3 deletions
diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index 445e80517cab..fc93c9488c76 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -371,4 +371,11 @@ */ #define __weak __attribute__((__weak__)) +/* + * Used by functions that use '__builtin_return_address'. These function + * don't want to be splited or made inline, which can make + * the '__builtin_return_address' get unexpected address. + */ +#define __fix_address noinline __noclone + #endif /* __LINUX_COMPILER_ATTRIBUTES_H */ diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index ca8afa382bf2..b51d07a727c9 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1195,7 +1195,8 @@ static inline bool skb_unref(struct sk_buff *skb) return true; } -void kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason); +void __fix_address +kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason); /** * kfree_skb - free an sk_buff with 'NOT_SPECIFIED' reason diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 974bbbbe7138..35d9d5958dc6 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -777,9 +777,10 @@ EXPORT_SYMBOL(__kfree_skb); * hit zero. Meanwhile, pass the drop reason to 'kfree_skb' * tracepoint. */ -void kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason) +void __fix_address +kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason) { - if (!skb_unref(skb)) + if (unlikely(!skb_unref(skb))) return; DEBUG_NET_WARN_ON_ONCE(reason <= 0 || reason >= SKB_DROP_REASON_MAX); |