From: Johan Hovold <johan@kernel.org>
To: Sjoerd Simons <sjoerd@collabora.com>
Cc: Chun-Kuang Hu <chunkuang.hu@kernel.org>,
Philipp Zabel <p.zabel@pengutronix.de>,
David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
Matthias Brugger <matthias.bgg@gmail.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com>,
CK Hu <ck.hu@mediatek.com>,
dri-devel@lists.freedesktop.org,
linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, kernel@collabora.com,
stable@vger.kernel.org
Subject: Re: [PATCH] drm/mediatek: Fix refcounting in mtk_drm_get_all_drm_priv
Date: Mon, 6 Oct 2025 11:49:47 +0200 [thread overview]
Message-ID: <aOOQu9Lu_3-EhtGd@hovoldconsulting.com> (raw)
In-Reply-To: <20251003-mtk-drm-refcount-v1-1-3b3f2813b0db@collabora.com>
On Fri, Oct 03, 2025 at 10:08:28AM +0200, Sjoerd Simons wrote:
> dev_get_drvdata simply returns the driver data part of drm_dev, which
> has its lifetime bound to the drm_dev.
No, that is not correct: the driver data goes away when the driver is
unbound, not when the device is freed.
> So only drop the reference in the
> error paths, on success they will get dropped later.
But there is indeed a partial fix for the device leak here which was
overlooked. Good catch.
> Cc: stable@vger.kernel.org
> Fixes: 9ba2556cef1df ("drm/mediatek: clean up driver data initialisation")
This is clearly not the commit that introduced the issue (even if I also
failed to notice the reference imbalance).
Since there is no need to keep the references, I've just sent a fix
which instead fixes this by dropping the previous partial fix:
https://lore.kernel.org/r/20251006093937.27869-1-johan@kernel.org
Johan
prev parent reply other threads:[~2025-10-06 9:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-03 8:08 [PATCH] drm/mediatek: Fix refcounting in mtk_drm_get_all_drm_priv Sjoerd Simons
2025-10-03 8:20 ` AngeloGioacchino Del Regno
2025-10-06 9:49 ` Johan Hovold [this message]
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