linux-kernel - Re: [PATCH RFC 0/9] Reduce ratelimit's false-positive misses

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <a92eb62d-aab1-4c19-a842-4797df443cf5@paulmck-laptop>
Date: Tue, 22 Apr 2025 07:57:31 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: Petr Mladek <pmladek@...e.com>
Cc: linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
	Kuniyuki Iwashima <kuniyu@...zon.com>,
	Mateusz Guzik <mjguzik@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Jon Pan-Doh <pandoh@...gle.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Karolina Stolarek <karolina.stolarek@...cle.com>
Subject: Re: [PATCH RFC 0/9] Reduce ratelimit's false-positive misses

On Tue, Apr 22, 2025 at 04:50:34PM +0200, Petr Mladek wrote:
> On Fri 2025-04-18 10:13:49, Paul E. McKenney wrote:
> > Hello!
> > 
> > This v2 series replaces open-coded uses of the ratelimit_state structure
> > with formal APIs, counts all rate-limit misses, replaces jiffies=0 special
> > case with a flag, provides a ___ratelimit() trylock-failure fastpath
> > to (almost) eliminate false-positive misses, and adds a simple test.
> > 
> > The key point of this series is the reduction of false-positive misses.
> > 
> > The individual patches are as follows:
> > 
> > 1.	Add trivial kunit test for ratelimit.
> 
> I have suggested few cosmetic changes for the above patch.

Thank you for the KUNIT tutorial, and I will apply these.

> > 2.	Create functions to handle ratelimit_state internals.
> > 
> > 3.	Avoid open-coded use of ratelimit_state structure's ->missed
> > 	field.
> > 
> > 4.	Avoid open-coded use of ratelimit_state structure's ->missed
> > 	field.
> > 
> > 5.	Avoid open-coded use of ratelimit_state structure's internals.
> > 
> > 6.	Convert the ->missed field to atomic_t.
> > 
> > 7.	Count misses due to lock contention.
> > 
> > 8.	Avoid jiffies=0 special case.
> > 
> > 9.	Reduce ___ratelimit() false-positive rate limiting, courtesy of
> > 	Petr Mladek.
> > 
> > 10.	Allow zero ->burst to disable ratelimiting.
> > 
> > 11.	Force re-initialization when rate-limiting re-enabled.
> > 
> > 12.	Don't flush misses counter if RATELIMIT_MSG_ON_RELEASE.
> > 
> > 13.	Avoid atomic decrement if already rate-limited.
> > 
> > 14.	Avoid atomic decrement under lock if already rate-limited.
> 
> The rest looks good. And I think that it is a great improvement.
> Feel free to use for the entire patchset:
> 
> Reviewed-by: Petr Mladek <pmladek@...e.com>

Again, thank you, and I will apply these to the series!

							Thanx, Paul