linux-kernel - Re: [PATCH] ring-buffer: Have the buffer update counter be atomic

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Message-ID: <20241011124408.6783a141@gandalf.local.home>
Date: Fri, 11 Oct 2024 12:44:08 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Petr Pavlu <petr.pavlu@...e.com>
Cc: LKML <linux-kernel@...r.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@...r.kernel.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH] ring-buffer: Have the buffer update counter be atomic

On Fri, 11 Oct 2024 17:20:12 +0200
Petr Pavlu <petr.pavlu@...e.com> wrote:

> I agree, I also noticed the missing locking in this function and it
> looked to me as something that should be fixed. I happen to have
> a somewhat more complex patch for it from a few months ago (pasted
> below). I think I didn't send it to the list because I then noticed
> other potential locking problems with the subbuf code, which I wanted to
> examine more closely first.
> 

Hmm, I think you are correct that the buffer->mutex isn't enough for the
sub buffer page and it requires a bigger window. I'll look at your patch
and also the logic to see if it can be squeezed down a little.

-- Steve