From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 75D3242E8F4 for ; Mon, 3 Aug 2026 18:25:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785781557; cv=none; b=NKjfSEDcWUjYC95c4YTVOdlrCTwHYN7PSRqwanKNhNHG2qWIMeC/ukH3OZoyE3NCBudSWDbQhrJ6JFVP0ygazkOWVNKuaGWVma/9lhMdNAX9Ekox/wZpC7EDLh0m8RC2VL1USMRpH9BlCviWeDcL7BUKI6W6VkIwUAmPQF03lXs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785781557; c=relaxed/simple; bh=NuIQEEXXwcqnyG80rVWtYIngc+G/yGskz/QzM1Hmh3o=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=PQVKbFv8LvjacdcjbWFj1oqKW4vgdfmm7sVo79S+JIBozRHPiZ8la4+LL1joA4LpzWb2+THudwNwudvQxB1q+9cI/8qW7TjAXCwA6zXHk+6j2s//2AW4mTAfT0D/ZlkROT1gvWJST2+62cVqTsN8BTNJmjlPBxJB1XE0mSJ7DKQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SMsQDEi5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="SMsQDEi5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 605441F000E9; Mon, 3 Aug 2026 18:25:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785781556; bh=Lg4Ei7T3x4PiumiOJaM6qKthCJPOhQgQiLuVjJMpNHA=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=SMsQDEi5IZpmZMKEhP1GgZo84mhcGNlwMCZp/xaMPf54ayUmVRt3u8ad9GWLlWUTL 7AqKjDYV4icgFWe29YIVK9ZkoChZaGpcQvOiwgL5Gb5T7KYj9opHD+vFpY3KGqih9w XAjdlAYVPsuHfQOceLVmTyTUNpwqS0l6IpNJXxDcTRN0YRRu6wUEF2v4VDqeeV+AvV 4DzP4m+mLOJ/Wu6LT/KTw2HunXvhpakXzM0ZvUem99E/+5z4Sc/UNpqTI5xKKF78/T 7+q/4PMe8jmKzABaRhvjwncKEVEFscjXtmiZ9YqOMv+3L4Zc4rZovwRidenmXwywJ/ /h8g8+Ro9Vfiw== From: sashiko-bot@kernel.org Subject: Re: [PATCH v9 03/22] drm/bridge: synopsys: dw-dp: Fix error handling in dw_dp_link_enable() Reply-To: sashiko-reviews@lists.linux.dev To: "Sebastian Reichel" Cc: devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org, conor+dt@kernel.org, robh@kernel.org In-Reply-To: <20260803-synopsys-dw-dp-improvements-v9-3-2e6e46135312@collabora.com> References: <20260803-synopsys-dw-dp-improvements-v9-0-2e6e46135312@collabora.com> <20260803-synopsys-dw-dp-improvements-v9-3-2e6e46135312@collabora.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 03 Aug 2026 18:25:54 +0000 Message-Id: <20260803182555.605441F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 2 potential issue(= s) to consider: New issues: - [High] The patch introduces a double-free bug by adding error path cleanu= ps (`phy_power_off()` and `drm_dp_link_power_down()`) in `dw_dp_link_enable= ()`. Because `atomic_enable` returns `void` and cannot abort a commit, the = DRM core unconditionally invokes `atomic_disable` later, executing a second= cleanup. Pre-existing issues: - [High] A preexisting bug where `phy_power_off()` is called on atomic disa= ble even if `phy_power_on()` failed in `dw_dp_link_enable()`, corrupting th= e PHY power state and regulator counts. -- --- Patch [3]: [PATCH v9 03/22] drm/bridge: synopsys: dw-dp: Fix error hand= ling in dw_dp_link_enable() --- commit 37d17812be83d5554aca9b8d15486591d59db100 Author: Sebastian Reichel drm/bridge: synopsys: dw-dp: Fix error handling in dw_dp_link_enable() This commit adds missing error handling in dw_dp_link_enable(), which failed to release resources it already requested before hitting an error. > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/br= idge/synopsys/dw-dp.c > index 06997208945ed..e332d66b80571 100644 > --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c > +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c > @@ -1636,10 +1636,19 @@ static int dw_dp_link_enable(struct dw_dp *dp) > =20 [Severity: High] This is a pre-existing issue, but does the same unbalanced power state happen if phy_power_on() fails? Looking at dw_dp_link_enable(), which executes just before this hunk: ret =3D phy_power_on(dp->phy); if (ret) return ret; If phy_power_on() fails, we return early. However, because atomic_enable() returns void and cannot abort a commit, the DRM core will still unconditionally call dw_dp_link_disable() later: dw_dp_link_disable() { ... phy_power_off(dp->phy); } Will this unconditional cleanup drop the phy power count to -1, permanently breaking subsequent power on attempts because the next phy_power_on() will only increment the count to 0 and skip hardware initialization? > ret =3D drm_dp_link_power_up(&dp->aux, dp->link.revision); > if (ret < 0) > - return ret; > + goto err_phy_power_off; > =20 > ret =3D dw_dp_link_train(dp); > + if (ret < 0) > + goto err_link_power_down; > + > + return 0; > + > +err_link_power_down: > + drm_dp_link_power_down(&dp->aux, dp->link.revision); > =20 > +err_phy_power_off: > + phy_power_off(dp->phy); [Severity: High] Will this explicit rollback result in phy_power_off() being called twice? Since the DRM core will unconditionally invoke atomic_disable() later when the commit fails, dw_dp_link_disable() will execute and perform its own cleanup: dw_dp_link_disable() { ... if (dw_dp_hpd_detect(dp)) drm_dp_link_power_down(&dp->aux, dp->link.revision); ... phy_power_off(dp->phy); } Doing the cleanup here in the error path means these functions will be called a second time. Can this double cleanup cause the phy power count to drop to -1, resulting in the same permanent breakage of the display pipeline described above? > return ret; > } --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260803-synopsys-d= w-dp-improvements-v9-0-2e6e46135312@collabora.com?part=3D3