linux-kernel - [PATCH 0/1] char: Use list_del_init() in misc

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Message-ID: <20250904063714.28925-1-xion.wang@mediatek.com>
Date: Thu, 4 Sep 2025 14:37:03 +0800
From: <xion.wang@...iatek.com>
To: Arnd Bergmann <arnd@...db.de>, Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>, Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, Akinobu
 Mita <akinobu.mita@...il.com>, Andrew Morton <akpm@...ux-foundation.org>
CC: <wsd_upstream@...iatek.com>, <huadian.liu@...iatek.com>, Xion Wang
	<xion.wang@...iatek.com>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-mediatek@...ts.infradead.org>
Subject: [PATCH 0/1] char: Use list_del_init() in misc_deregister()

From: Xion Wang <xion.wang@...iatek.com>

Hi all,

This patch updates the misc_deregister() function to use list_del_init()
instead of list_del() when removing the device from the list.
While list_del() poisons the list pointers to catch invalid usage,
it does not reset the list head. 
If misc_deregister() is called more than once on the same device, 
list_empty() will not return true and list_del() may be called again,
leading to undefined behavior.

By switching to list_del_init(), we ensure the list head is reinitialized,
making the code more robust against double deregistration and
allowing safe usage of list_empty() after deregistration.

Fixes: b329becfc78b1 ("char: add WARN_ON() in misc_deregister()")

Let me know if you have any questions or suggestions.

Thanks,
Xion Wang

Xion Wang (1):
  char: Use list_del_init() in misc_deregister() to reinitialize list
    pointer

 drivers/char/misc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.45.2