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Tue, 09 Jun 2026 02:51:37 -0700 (PDT) X-Received: by 2002:a05:622a:4c06:b0:517:5af6:77f9 with SMTP id d75a77b69052e-51795b3af28mr168053881cf.3.1780998696650; Tue, 09 Jun 2026 02:51:36 -0700 (PDT) Received: from [192.168.120.170] ([178.235.128.140]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-bf0559f35c2sm1023106466b.61.2026.06.09.02.51.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Jun 2026 02:51:35 -0700 (PDT) Message-ID: <1d26aa46-fa37-4969-aca4-aadde6ad9303@oss.qualcomm.com> Date: Tue, 9 Jun 2026 11:51:33 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] clk: qcom: clk-pll: reject vote enable on orphan parent To: Herman van Hazendonk , sboyd@kernel.org Cc: Bjorn Andersson , Michael Turquette , linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260602062927.467249-1-github.com@herrie.org> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <20260602062927.467249-1-github.com@herrie.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-GUID: 4s2Peo_VwBQQKmGf-GhEYvXsM9ZD5E2E X-Authority-Analysis: v=2.4 cv=aa9RWxot c=1 sm=1 tr=0 ts=6a27e22a cx=c_pps a=WeENfcodrlLV9YRTxbY/uA==:117 a=PRfkaYvzSr8QmIIGAkY2Sg==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22 a=EUspDBNiAAAA:8 a=Yo3Wi9bsOxpmy9sskUYA:9 a=QEXdDO2ut3YA:10 a=kacYvNCVWA4VmyqE58fU:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjA5MDA5MSBTYWx0ZWRfX9CCOPcAaiO7b tOC3w25Jr7wqTIwWdFntfrEFJp0G6DKfl1hQexauSR3z2IxwVzS2MKNApG+prs3m6oRpOv2/y1F zIPyfTgAtce+7z5G1cmGgDnySMUHHeI0as6T5+F07cijIJvtwcWPxh3NoHqXrBuMD2sjhIUZlef bwjBSmoCP5um8V52JmEW8X4Razo4uSoNSECTL2e3uqlnlLYHT4PWd5QFUes2bOgdywiDQuA2GfW 7AhVOEaXyHouxe5xJMAqu087NG0lx59jrGL2SLRMH+pm/jYaNb6jhTI8dTPklk6bfGVhVigT26F skfKrs54MlpuceXDuHp1Xtr6WNhqCU5DXfaVHuqRpstG0RhZCRu29Zn+L3k1jrc2pN5Q8/QNq2/ h/0imATbvmfRZ0N/uILFkhYuHFZDUxuICOwyJb8ihbXLbXAgE77aWKeFl4nMYJfQYj0bRFF+zNO AiW9CyiVs2E73m4tp+A== X-Proofpoint-ORIG-GUID: 4s2Peo_VwBQQKmGf-GhEYvXsM9ZD5E2E X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-09_02,2026-06-09_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 suspectscore=0 priorityscore=1501 impostorscore=0 adultscore=0 spamscore=0 bulkscore=0 malwarescore=0 clxscore=1015 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606090091 On 6/2/26 8:29 AM, Herman van Hazendonk wrote: > clk_pll_vote_enable() unconditionally feeds the result of > clk_hw_get_parent(hw) through to_clk_pll() and on to wait_for_pll(). > The common clock framework permits clk_enable() on an orphan clock > (supplier not bound yet), in which case clk_hw_get_parent() returns > NULL. to_clk_pll(NULL) then yields container_of(NULL, struct clk_pll, > clkr) -- a non-NULL bogus pointer pointing into the negative offset > of struct clk_pll. > > wait_for_pll() reaches for the parent's name via > clk_hw_get_name(&pll->clkr.hw). Because clkr sits at a fixed offset > inside struct clk_pll, &pll->clkr.hw cancels the to_clk_pll offset > exactly back to NULL and clk_hw_get_name() then dereferences > core->name on a NULL clk_hw, panicking the kernel. > > This is reachable today: gcc-msm8960.c and gcc-apq8064.c register a > pll4_vote whose parent (pll4) lives in lcc-msm8960.c, and the future > gcc-msm8660 pll4_vote does the same. If anything calls clk_enable() > on pll4_vote between gcc probe and the LCC clock controller binding, > the system panics. The exposure widens as more SoCs adopt the same > cross-controller voter pattern. Hm, I think this is a side-effect of the olden global clock by-name lookup (i.e. parent_data.name). Nowadays this shouldn't be much of an issue because of fw_devlink ensuring correct ordering. There is already a reference in the dts, since about 2022: 80787e417f30 ("ARM: dts: qcom: msm8960: add clocks to the GCC device node") Are there any other cross-dependencies between GCC and LCC? Anyway, for this patch: Reviewed-by: Konrad Dybcio Konrad