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From: Florian Weimer <fweimer@redhat.com>
To: Thomas Gleixner <tglx@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
	"André Almeida" <andrealmeid@igalia.com>,
	"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
	"Carlos O'Donell" <carlos@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"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 8/8] x86/vdso: Implement __vdso_futex_robust_try_unlock()
Date: Tue, 17 Mar 2026 09:28:41 +0100	[thread overview]
Message-ID: <lhu4imeoo5i.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <20260316164951.484640267@kernel.org> (Thomas Gleixner's message of "Mon, 16 Mar 2026 18:13:34 +0100")

* Thomas Gleixner:

> Arguably this could be avoided by providing separate functions and making
> the IP range for the quick check in the exit to user path cover the whole
> text section which contains the two functions. But that's not a win at all
> because:
>
>    1) User space needs to handle the two variants instead of just
>       relying on a bit which can be saved in the mutex at
>       initialization time.

I'm pretty sure that on the user-space side, we wouldn't have
cross-word-size operations (e.g., 64-bit code working on both 64-bit and
32-bit robust mutexes).  Certainly not within libcs.  The other point
about complexity is of course still valid.

Thanks,
Florian


  parent reply	other threads:[~2026-03-17  8:28 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
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 [this message]
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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