linux-kernel - Re: [PATCH RESEND 1/3] locking: add rwsem_is_write

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: <20260116151215.GH831050@noisy.programming.kicks-ass.net>
Date: Fri, 16 Jan 2026 16:12:15 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...nel.org>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>,
	Shakeel Butt <shakeel.butt@...ux.dev>, Jann Horn <jannh@...gle.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-rt-devel@...ts.linux.dev, Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>, Boqun Feng <boqun.feng@...il.com>,
	Waiman Long <longman@...hat.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Clark Williams <clrkwllms@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH RESEND 1/3] locking: add rwsem_is_write_locked(), update
 non-lockdep asserts

On Fri, Jan 16, 2026 at 01:36:45PM +0000, Lorenzo Stoakes wrote:
> As part of adding some additional lock asserts in mm, we wish to be able to
> determine if a read/write semaphore is write-locked, so add
> rwsem_is_write_locked() to do the write-lock equivalent of
> rwsem_is_locked().
> 
> While we're here, update rwsem_assert_[write_]held_nolockdep() to utilise
> the rwsem_is_[write_]locked() helpers directly to reduce code duplication,
> and also update rwsem_is_locked() to take a const rwsem and return a
> boolean.

There is a long history of abuse of _is_locked() primitives. I don't
suppose you read the email thread that led to
rwsem_assert_held_*_nolockdep() by any chance?