Re: [PATCH v2 2/3] compiler: inline does not imply notrace

[Nadav Amit <nadav.amit@gmail.com>]

> On May 25, 2023, at 7:28 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> On Thu, 25 May 2023 14:00:39 -0700
> Nadav Amit <nadav.amit@gmail.com> wrote:
> 
>> From: Nadav Amit <namit@vmware.com>
>> 
>> Functions that are marked as "inline" are currently also not tracable.
>> This limits tracing functionality for many functions for no reason.
>> Apparently, this has been done for two reasons.
>> 
>> First, as described in commit 5963e317b1e9d2a ("ftrace/x86: Do not
>> change stacks in DEBUG when calling lockdep"), it was intended to
>> prevent some functions that cannot be traced from being traced as these
>> functions were marked as inline (among others).
>> 
>> Yet, this change has been done a decade ago, and according to Steven
>> Rostedt, ftrace should have improved and hopefully resolved nested
>> tracing issues by now. Arguably, if functions that should be traced -
>> for instance since they are used during tracing - still exist, they
>> should be marked as notrace explicitly.
>> 
>> The second reason, which Steven raised, is that attaching "notrace" to
>> "inline" prevented tracing differences between different configs, which
>> caused various problem. This consideration is not very strong, and tying
>> "inline" and "notrace" does not seem very beneficial. The "inline"
>> keyword is just a hint, and many functions are currently not tracable
>> due to this reason.
>> 
>> Disconnect "inline" from "notrace".
> 
> FYI, I have a patch queued (still needs to go through testing) that
> already does this ;-)
> 
> https://lore.kernel.org/all/20230502164102.1a51cdb4@gandalf.local.home/

Ugh. If you cc’d me, I wouldn’t bother you during your vacation. :)

I think you may like the first patch in my series to precede this patch
though as some of the function I marked as “notrace" are currently “inline”.

Let me know how you want to proceed, so I would know how to break this
series.