From: Dan Williams <dan.j.williams@intel.com>
To: Lukas Wunner <lukas@wunner.de>, Dan Williams <dan.j.williams@intel.com>
Cc: <gregkh@linuxfoundation.org>,
Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
Marc Herbert <marc.herbert@intel.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-pci@vger.kernel.org>,
<linux-coco@lists.linux.dev>, <alsa-devel@alsa-project.org>
Subject: Re: [PATCH 1/3] sysfs: Fix crash on empty group attributes array
Date: Sat, 27 Apr 2024 09:49:41 -0700 [thread overview]
Message-ID: <662d2ca522cc6_b6e02942d@dwillia2-mobl3.amr.corp.intel.com.notmuch> (raw)
In-Reply-To: <Ziv9984CJeQ4muZy@wunner.de>
Lukas Wunner wrote:
[..]
> So in this case I'm able to dodge the bullet because the empty
> signatures/ directory for CMA-incapable devices is only briefly
> visible in the series. Nobody will notice unless they apply
> only a subset of the series.
>
> But I want to raise awareness that the inability to hide
> empty attribute groups feels awkward.
That is fair, it was definitely some gymnastics to only change user
visible behavior for new "invisible aware" attribute groups that opt-in
while leaving all the legacy cases alone.
The concern is knowing when it is ok to call an is_visible() callback
with a NULL @attr argument, or knowing when an empty array actually
means "hide the group directory".
We could add a sentinel value to indicate "I am an empty attribute list
*AND* I want my directory hidden by default". However, that's almost
identical to requiring a placeholder attribute in the list just to make
__first_visible() happy.
Other ideas? I expect this issue to come up again because dynamically
populated attribute arrays of a statically defined group is a useful
mechanism. I might need this in the PCI TSM enabling... but having at
least one attribute there is likely not a problem.
next prev parent reply other threads:[~2024-04-27 16:49 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-22 20:40 [PATCH 0/3] sysfs: Group visibility fixups Dan Williams
2024-02-22 20:40 ` [PATCH 1/3] sysfs: Fix crash on empty group attributes array Dan Williams
2024-02-22 21:14 ` Rafael J. Wysocki
2024-02-22 22:03 ` Dan Williams
2024-02-22 23:15 ` Dan Williams
2024-04-22 9:20 ` Lukas Wunner
2024-04-26 17:59 ` Dan Williams
2024-04-26 19:18 ` Lukas Wunner
2024-04-27 11:05 ` Greg KH
2024-04-27 16:49 ` Dan Williams [this message]
2024-04-27 21:14 ` Lukas Wunner
2024-04-27 21:33 ` Dan Williams
2024-04-27 22:39 ` Dan Williams
2024-04-27 23:09 ` Dan Williams
2024-04-28 10:08 ` Lukas Wunner
2024-04-29 17:47 ` Dan Williams
2024-02-22 20:41 ` [PATCH 2/3] sysfs: Document new "group visible" helpers Dan Williams
2024-02-22 20:41 ` [PATCH 3/3] sysfs: Introduce DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE() Dan Williams
2024-02-23 6:33 ` [PATCH 0/3] sysfs: Group visibility fixups Greg KH
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