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([101.36.106.88]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d315ef11e8sm2383365ad.1.2026.08.10.23.34.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Aug 2026 23:34:57 -0700 (PDT) From: Guangshuo Li To: Olivia Mackall , Herbert Xu , Maxime Coquelin , Alexandre Torgue , Guangshuo Li , Daniel Thompson , Linus Walleij , 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 v2] hwrng: stm32: fix usage_count leak when autosuspend_delay is negative Date: Tue, 11 Aug 2026 14:34:42 +0800 Message-ID: <20260811063442.3058074-1-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 runtime PM is enabled with pm_runtime_enable() and the matching pm_runtime_dont_use_autosuspend() is not called on driver teardown. 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. Use devm_pm_runtime_enable() so that pm_runtime_dont_use_autosuspend() and pm_runtime_disable() are automatically called on probe failure and driver teardown. With runtime PM cleanup handled by devres, stm32_rng_remove() is no longer needed. 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 Reviewed-by: Daniel Thompson (RISCstar) Reviewed-by: Linus Walleij Reviewed-by: Maxime M=C3=A9r=C3=A9 --- v2: - Replace pm_runtime_enable() with devm_pm_runtime_enable() to handle runtime PM cleanup through devres. - Remove stm32_rng_remove() and the manual cleanup on the probe failure path. drivers/char/hw_random/stm32-rng.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/st= m32-rng.c index 9a8c00586ab0..f5bfe54c01dc 100644 --- a/drivers/char/hw_random/stm32-rng.c +++ b/drivers/char/hw_random/stm32-rng.c @@ -368,11 +368,6 @@ static int stm32_rng_init(struct hwrng *rng) return 0; } =20 -static void stm32_rng_remove(struct platform_device *ofdev) -{ - pm_runtime_disable(&ofdev->dev); -} - static int __maybe_unused stm32_rng_runtime_suspend(struct device *dev) { struct stm32_rng_private *priv =3D dev_get_drvdata(dev); @@ -590,7 +585,9 @@ static int stm32_rng_probe(struct platform_device *ofde= v) =20 pm_runtime_set_autosuspend_delay(dev, 100); pm_runtime_use_autosuspend(dev); - pm_runtime_enable(dev); + ret =3D devm_pm_runtime_enable(dev); + if (ret) + return ret; =20 return devm_hwrng_register(dev, &priv->rng); } @@ -602,7 +599,6 @@ static struct platform_driver stm32_rng_driver =3D { .of_match_table =3D stm32_rng_match, }, .probe =3D stm32_rng_probe, - .remove =3D stm32_rng_remove, }; =20 module_platform_driver(stm32_rng_driver); --=20 2.43.0