linux-kernel - Re: [GIT PULL] tracing: Fixes for v6.13-rc7

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Message-ID: <20250116101024.2d8040d0@gandalf.local.home>
Date: Thu, 16 Jan 2025 10:10:24 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mark Rutland <mark.rutland@....com>, Mathieu
 Desnoyers <mathieu.desnoyers@...icios.com>, Shrikanth Hegde
 <sshegde@...ux.ibm.com>
Subject: Re: [GIT PULL] tracing: Fixes for v6.13-rc7

On Thu, 16 Jan 2025 09:53:33 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

>   But the irqsoff and wakeup latency tracers, when the "display-graph"
>   option was set, would use the function graph tracer to calculate the
>   times of functions during the latency. The movement of the calltime
>   calculation made the value zero for these tracers, and the output
>   no longer showed the length of time of each tracer, but instead the
>   absolute timestamp of when the function returned (rettime - calltime
>   where calltime is now zero).

FYI,

I have a patch that removes the calltime and rettime fields from the
generic structure as they should not be used in the generic code. That is
how I found this bug. I noticed that the irqsoff and wakeup tracers used
that field as well, and when I tested those tracers with the display-graph
option enabled, that's when I noticed the regression.

But that change is a cleanup and not appropriate for an rc release. This
was more of a work around to fix the regression. The proper fix will come
in 6.14.

-- Steve