Messages in this thread | | | From | Menglong Dong <> | Date | Fri, 19 Aug 2022 00:31:44 +0800 | Subject | Re: [PATCH net-next v4] net: skb: prevent the split of kfree_skb_reason() by gcc |
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Hello, On Wed, Aug 17, 2022 at 11:54 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > > On Mon, Aug 15, 2022 at 8:29 PM <menglong8.dong@gmail.com> wrote: > > > > From: Menglong Dong <imagedong@tencent.com> > > > > 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(). > > Does the existing __noclone function attribute help at all here? > > If not, surely there's an attribute that's more precise than "disable > most optimization outright." > > https://unix.stackexchange.com/questions/223013/function-symbol-gets-part-suffix-after-compilation > https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute > > Perhaps noipa might also work here? >
In my testing, both 'noclone' and 'noipa' both work! As for the '-fdisable-ipa-fnsplit', it seems it's not supported by gcc, and I failed to find any documentation of it.
I think that the '__noclone' is exactly what I needed! Just like what saied in this link:
https://stackoverflow.com/questions/34086769/purpose-of-function-attribute-noclone
I appreciate your advice, and it seems it's not needed to add new attributes to the compiler_attributes.h.
Thanks! Menglong Dong
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