From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Thomas Gleixner <tglx@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Cc: "André Almeida" <andrealmeid@igalia.com>,
"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
"Carlos O'Donell" <carlos@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Florian Weimer" <fweimer@redhat.com>,
"Rich Felker" <dalias@aerifal.cx>,
"Torvald Riegel" <triegel@redhat.com>,
"Darren Hart" <dvhart@infradead.org>,
"Ingo Molnar" <mingo@kernel.org>,
"Davidlohr Bueso" <dave@stgolabs.net>,
"Arnd Bergmann" <arnd@arndb.de>,
"Liam R . Howlett" <Liam.Howlett@oracle.com>
Subject: Re: [patch 4/8] futex: Add support for unlocking robust futexes
Date: Mon, 16 Mar 2026 14:24:35 -0400 [thread overview]
Message-ID: <9634b949-4585-4ba1-981a-e328a71c5c49@efficios.com> (raw)
In-Reply-To: <20260316164951.209959583@kernel.org>
On 2026-03-16 13:13, Thomas Gleixner wrote:
[...]
>
> PI futexes have a similar problem both for the non-contented user space
> unlock and the in kernel unlock:
>
> 1) robust_list_set_op_pending(mutex);
> 2) robust_list_remove(mutex);
>
> lval = gettid();
> 3) if (!atomic_try_cmpxchg(lock, lval, 0))
> 4) sys_futex(UNLOCK_PI,....);
> 5) robust_list_clear_op_pending();
>
We can document that the window in this case is between #3 and #5.
Other than this detail:
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
next prev parent reply other threads:[~2026-03-16 18:24 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 17:12 [patch 0/8] futex: Address the robust futex unlock race for real Thomas Gleixner
2026-03-16 17:12 ` [patch 1/8] futex: Move futex task related data into a struct Thomas Gleixner
2026-03-16 17:55 ` Mathieu Desnoyers
2026-03-17 2:24 ` André Almeida
2026-03-17 9:52 ` Thomas Gleixner
2026-03-16 17:13 ` [patch 2/8] futex: Move futex related mm_struct " Thomas Gleixner
2026-03-16 18:00 ` Mathieu Desnoyers
2026-03-16 17:13 ` [patch 3/8] futex: Provide UABI defines for robust list entry modifiers Thomas Gleixner
2026-03-16 18:02 ` Mathieu Desnoyers
2026-03-17 2:38 ` André Almeida
2026-03-17 9:53 ` Thomas Gleixner
2026-03-16 17:13 ` [patch 4/8] futex: Add support for unlocking robust futexes Thomas Gleixner
2026-03-16 18:24 ` Mathieu Desnoyers [this message]
2026-03-17 16:17 ` André Almeida
2026-03-17 20:46 ` Peter Zijlstra
2026-03-17 22:40 ` Thomas Gleixner
2026-03-18 8:02 ` Peter Zijlstra
2026-03-18 8:06 ` Florian Weimer
2026-03-18 14:47 ` Peter Zijlstra
2026-03-18 16:03 ` Thomas Gleixner
2026-03-16 17:13 ` [patch 5/8] futex: Add robust futex unlock IP range Thomas Gleixner
2026-03-16 18:36 ` Mathieu Desnoyers
2026-03-17 19:19 ` André Almeida
2026-03-16 17:13 ` [patch 6/8] futex: Provide infrastructure to plug the non contended robust futex unlock race Thomas Gleixner
2026-03-16 18:35 ` Mathieu Desnoyers
2026-03-16 20:29 ` Thomas Gleixner
2026-03-16 20:52 ` Mathieu Desnoyers
2026-03-16 17:13 ` [patch 7/8] x86/vdso: Prepare for robust futex unlock support Thomas Gleixner
2026-03-16 17:13 ` [patch 8/8] x86/vdso: Implement __vdso_futex_robust_try_unlock() Thomas Gleixner
2026-03-16 19:19 ` Mathieu Desnoyers
2026-03-16 21:02 ` Thomas Gleixner
2026-03-16 22:35 ` Mathieu Desnoyers
2026-03-16 21:14 ` Thomas Gleixner
2026-03-16 21:29 ` Thomas Gleixner
2026-03-17 7:25 ` Thomas Weißschuh
2026-03-17 9:51 ` Thomas Gleixner
2026-03-17 11:17 ` Thomas Weißschuh
2026-03-18 16:17 ` Thomas Gleixner
2026-03-19 7:41 ` Thomas Weißschuh
2026-03-19 8:53 ` Florian Weimer
2026-03-19 9:04 ` Thomas Weißschuh
2026-03-19 9:08 ` Peter Zijlstra
2026-03-19 23:31 ` Thomas Gleixner
2026-03-19 10:36 ` Sebastian Andrzej Siewior
2026-03-19 10:49 ` Thomas Weißschuh
2026-03-19 10:55 ` Sebastian Andrzej Siewior
2026-03-17 8:28 ` Florian Weimer
2026-03-17 9:36 ` Thomas Gleixner
2026-03-17 10:37 ` Florian Weimer
2026-03-17 22:32 ` Thomas Gleixner
2026-03-18 22:08 ` Thomas Gleixner
2026-03-18 22:10 ` Peter Zijlstra
2026-03-19 2:05 ` André Almeida
2026-03-19 7:10 ` Thomas Gleixner
2026-03-17 15:33 ` Uros Bizjak
2026-03-18 8:21 ` Thomas Gleixner
2026-03-18 8:32 ` Uros Bizjak
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