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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, prevent this kind of optimization to kfree_skb_reason() by making the optimize level to "O1". I think these should be better method instead of this "O1", but I can't figure it out...... This optimization CAN happen, which depend on the behavior of gcc. I'm not able to reproduce it in the latest kernel code, but it happens in my kernel of version 5.4.119. Maybe the latest code already do someting that prevent this happen? Signed-off-by: Menglong Dong <imagedong@tencent.com>
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