From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: tglx@linutronix.de, axboe@kernel.dk,
linux-kernel@vger.kernel.org, mingo@redhat.com,
dvhart@infradead.org, dave@stgolabs.net, andrealmeid@igalia.com,
Andrew Morton <akpm@linux-foundation.org>,
urezki@gmail.com, hch@infradead.org, lstoakes@gmail.com,
Arnd Bergmann <arnd@arndb.de>,
linux-api@vger.kernel.org, linux-mm@kvack.org,
linux-arch@vger.kernel.org, malteskarupke@web.de,
Geert Uytterhoeven <geert@linux-m68k.org>
Subject: Re: [PATCH v3 10/15] futex: Add sys_futex_requeue()
Date: Fri, 22 Sep 2023 13:03:35 +0200 [thread overview]
Message-ID: <20230922110335.GC7080@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <ZQ1fx29+b8PmLVk6@gmail.com>
On Fri, Sep 22, 2023 at 11:35:03AM +0200, Ingo Molnar wrote:
>
> * peterz@infradead.org <peterz@infradead.org> wrote:
>
> > --- linux-2.6.orig/kernel/futex/syscalls.c
> > +++ linux-2.6/kernel/futex/syscalls.c
> > @@ -396,6 +396,44 @@ SYSCALL_DEFINE6(futex_wait,
> > return ret;
> > }
> >
> > +/*
> > + * sys_futex_requeue - Requeue a waiter from one futex to another
> > + * @waiters: array describing the source and destination futex
> > + * @flags: unused
> > + * @nr_wake: number of futexes to wake
> > + * @nr_requeue: number of futexes to requeue
> > + *
> > + * Identical to the traditional FUTEX_CMP_REQUEUE op, except it is part of the
> > + * futex2 family of calls.
> > + */
> > +
> > +SYSCALL_DEFINE4(futex_requeue,
> > + struct futex_waitv __user *, waiters,
> > + unsigned int, flags,
> > + int, nr_wake,
> > + int, nr_requeue)
> > +{
> > + struct futex_vector futexes[2];
> > + u32 cmpval;
> > + int ret;
> > +
> > + if (flags)
> > + return -EINVAL;
>
> Small detail, but isn't -ENOSYS the canonical error code for functionality
> not yet implemented - which the unused 'flags' ABI is arguably?
>
> -EINVAL is for recognized but incorrect parameters, such as:
IIUC 'unknown flag' falls into the -EINVAL return category. Here we
happen to have no known flags, but that should not matter.
next prev parent reply other threads:[~2023-09-22 11:04 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-21 10:45 [PATCH v3 00/15] futex: More futex2 bits peterz
2023-09-21 10:45 ` [PATCH v3 04/15] futex: Validate futex value against futex size peterz
2023-09-21 10:45 ` [PATCH v3 05/15] futex: Add sys_futex_wake() peterz
2023-09-21 10:45 ` [PATCH v3 07/15] futex: Add sys_futex_wait() peterz
2023-09-21 10:45 ` [PATCH v3 08/15] futex: Propagate flags into get_futex_key() peterz
2023-09-21 10:45 ` [PATCH v3 09/15] futex: Add flags2 argument to futex_requeue() peterz
2023-09-21 10:45 ` [PATCH v3 10/15] futex: Add sys_futex_requeue() peterz
2023-09-22 9:35 ` Ingo Molnar
2023-09-22 11:03 ` Peter Zijlstra [this message]
2023-09-22 13:56 ` Jens Axboe
2023-09-21 10:45 ` [PATCH v3 11/15] mm: Add vmalloc_huge_node() peterz
2023-09-21 10:45 ` [PATCH v3 12/15] futex: Implement FUTEX2_NUMA peterz
2023-09-21 10:45 ` [PATCH v3 13/15] futex: Propagate flags into futex_get_value_locked() peterz
2023-09-21 10:45 ` [PATCH v3 14/15] futex: Enable FUTEX2_{8,16} peterz
2023-09-21 10:45 ` [PATCH v3 15/15] futex,selftests: Extend the futex selftests peterz
2023-09-21 11:41 ` Peter Zijlstra
[not found] ` <20230921105248.048643656@noisy.programming.kicks-ass.net>
2023-09-21 15:14 ` [PATCH v3 06/15] futex: FLAGS_STRICT Thomas Gleixner
2023-09-22 20:01 ` futex2 numa stuff Peter Zijlstra
2023-09-22 20:01 ` [PATCH 15/15] futex,selftests: Extend the futex selftests Peter Zijlstra
2023-09-22 20:01 ` [PATCH 16/15] futex,selftests: Extend the futex selftests for NUMA Peter Zijlstra
2023-09-22 20:01 ` [PATCH 17/15] [HACK] futex: Force futex hash collision Peter Zijlstra
2023-09-28 13:40 ` futex2 numa stuff Davidlohr Bueso
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