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From: Tejun Heo <tj@kernel.org>
To: Krystian Kaniewski <krystianmkaniewski@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Ian Kent <raven@themaw.net>, Danilo Krummrich <dakr@kernel.org>,
	Johan Hovold <johan@kernel.org>, Len Brown <lenb@kernel.org>,
	Pavel Machek <pavel@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
	driver-core@lists.linux.dev, linux-pm@vger.kernel.org,
	autofs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	syzbot+002fb7b2d0bc53bf7e75@syzkaller.appspotmail.com
Subject: Re: [PATCH v2 0/2] kernfs, sysfs: refuse splice on /sys/power/resume
Date: Tue, 03 Nov 2026 05:51:31 -1000	[thread overview]
Message-ID: <c943b8e768ef766b0f6563b6085e99fe@kernel.org> (raw)
In-Reply-To: <cover.1793715774.git.krystianmkaniewski@gmail.com>

Hello, Krystian.

On Tue, Nov 03, 2026 at 03:57:41PM +0100, Krystian Kaniewski wrote:
> Patch 1 adds SYSFS_LOOKUP and kernfs_ops->may_lookup. Writable opens of a
> marked file refuse both splice directions. Their of->mutex and seq_file lock
> use separate classes. Read-only opens retain splice support.

Can we be explicit and name the flag after what it does, e.g.
SYSFS_NO_SPLICE and kernfs_ops->no_splice?

> The new property cannot be combined with mmap or preallocated buffers.
> Kernfs rejects those combinations for direct callers, and sysfs rejects
> SYSFS_LOOKUP together with SYSFS_PREALLOC before selecting operations.
> Binary attributes do not support SYSFS_LOOKUP and reject it at creation.

Can we keep the rest minimal? With /sys/power/resume the only user, I don't
think things like the mmap and prealloc combination checks or the binary
attribute rejections are needed.

Thanks.

--
tejun

      parent reply	other threads:[~2026-11-03 15:51 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-03 14:57 Krystian Kaniewski
2026-11-03 14:57 ` [PATCH v2 1/2] kernfs, sysfs: refuse splice on writable files that look up paths Krystian Kaniewski
2026-11-03 14:57 ` [PATCH v2 2/2] PM: hibernate: refuse splice on /sys/power/resume Krystian Kaniewski
2026-11-03 15:51 ` Tejun Heo [this message]

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