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([101.76.249.46]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3925fd95794sm5282123a91.7.2026.08.08.00.46.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Aug 2026 00:46:50 -0700 (PDT) From: Guangshuo Li To: Olivia Mackall , Herbert Xu , Maxime Coquelin , Alexandre Torgue , Guangshuo Li , Linus Walleij , Daniel Thompson , linux-crypto@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Subject: [PATCH] hwrng: stm32: fix usage_count leak when autosuspend_delay is negative Date: Sat, 8 Aug 2026 15:45:10 +0800 Message-ID: <20260808074510.2655473-1-lgs201920130244@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" stm32_rng_probe() calls pm_runtime_use_autosuspend(), but neither the probe failure path nor stm32_rng_remove() calls the matching pm_runtime_dont_use_autosuspend() before disabling runtime PM. If the autosuspend delay is set to a negative value while autosuspend is enabled, the runtime PM core increments usage_count to prevent runtime suspend. Without calling pm_runtime_dont_use_autosuspend() during teardown, this reference is not dropped and usage_count remains unbalanced. Add the missing pm_runtime_dont_use_autosuspend() calls to both the probe failure and remove paths before disabling runtime PM. This issue was found by manual code inspection. Fixes: c6a97c42e399 ("hwrng: stm32 - add support for STM32 HW RNG") Cc: stable@vger.kernel.org Signed-off-by: Guangshuo Li --- drivers/char/hw_random/stm32-rng.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/st= m32-rng.c index 9a8c00586ab0..6de4c52bd4d6 100644 --- a/drivers/char/hw_random/stm32-rng.c +++ b/drivers/char/hw_random/stm32-rng.c @@ -370,6 +370,7 @@ static int stm32_rng_init(struct hwrng *rng) =20 static void stm32_rng_remove(struct platform_device *ofdev) { + pm_runtime_dont_use_autosuspend(&ofdev->dev); pm_runtime_disable(&ofdev->dev); } =20 @@ -592,7 +593,14 @@ static int stm32_rng_probe(struct platform_device *ofd= ev) pm_runtime_use_autosuspend(dev); pm_runtime_enable(dev); =20 - return devm_hwrng_register(dev, &priv->rng); + ret =3D devm_hwrng_register(dev, &priv->rng); + if (ret) { + pm_runtime_dont_use_autosuspend(dev); + pm_runtime_disable(dev); + return ret; + } + + return 0; } =20 static struct platform_driver stm32_rng_driver =3D { --=20 2.43.0