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

From: Steven Rostedt
Date: Thu May 25 2023 - 22:28:59 EST

On Thu, 25 May 2023 14:00:39 -0700
Nadav Amit <nadav.amit@xxxxxxxxx> wrote:

> From: Nadav Amit <namit@xxxxxxxxxx>
> 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 ;-)

-- Steve