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Wed, 25 Jun 2025 01:14:53 -0700 (PDT) From: Bartosz Golaszewski Date: Wed, 25 Jun 2025 10:14:51 +0200 Subject: [PATCH 4/4] firmware: qcom: scm: request the waitqueue irq *after* initializing SCM Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250625-qcom-scm-race-v1-4-45601e1f248b@linaro.org> References: <20250625-qcom-scm-race-v1-0-45601e1f248b@linaro.org> In-Reply-To: <20250625-qcom-scm-race-v1-0-45601e1f248b@linaro.org> To: Bjorn Andersson , Konrad Dybcio Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2364; i=bartosz.golaszewski@linaro.org; h=from:subject:message-id; bh=WAejpHm2zxrZJBXpdQ3X3+gbcsisAGeTsZWllPcnvVk=; b=owEBbQKS/ZANAwAKARGnLqAUcddyAcsmYgBoW6/5L3o/CKqhgpj7XEAIb423ovwfa9zx4oBik ku6GviTFXCJAjMEAAEKAB0WIQQWnetsC8PEYBPSx58Rpy6gFHHXcgUCaFuv+QAKCRARpy6gFHHX ckV/D/0cIBqLLdI1q+I7qwkYxogp1KdGIJY8gdysCR1uTWvOZ7CVXIqsoEQULeexm2qONp1wb9n jFKoX7cnQc3L1KGcunsyqnTCCraR0HV85ljXYUhBQxRjaOW66XsCnO6T6ubvXoGmUCXJ/cMfaZm 7CvzczqJl8lv9+1yCtrBIeODyejwx3ttyT1vvCRzhc07EKXzw/PPgsCkX1HiJd+AKdpI4FBiqaa A84yon0MDiw4pvXaIVtvWz8IX/tOYO0AhMWlnMb92mK32q44VwaydO+PQ1gTfyJ7o4uzmyTA02w TF6WzdZ1+jmZagTrzIfxKXL4phwQJw5Zx1c4eyQ80gEyqyE+uKb1tCH/HMEzUZH7mXqTG6L1tt2 mur47bnJPalaPGQf3M6p7Hym1LlN515Xf4/9xOV4+W811i78cIKyIRuVAxhxCUxPUnk9rUms5Um LJh0Dvm3X+hEbizB2XYB0MlPgKa4ALZ+UbKfPwhY22CAQcWixqbAuv3l1Am2qwXxMmTGNAP/xFj nB5cPJTQH1s9TVhLukcT904s3FVrHQ96dRNGYgi0kmQ2WRArljdMwaVNxcdzVFop9VDRqj7Mqx7 B4Mzdj0tAUEYs6DjhhC2TB5lQ1F/mQG4mjZ4q7yeC7JRZ8hi3yvq579YLqic0gxoNdbcOgrqNQU a6YDSNp7TrBv3Ew== X-Developer-Key: i=bartosz.golaszewski@linaro.org; a=openpgp; fpr=169DEB6C0BC3C46013D2C79F11A72EA01471D772 From: Bartosz Golaszewski There's a subtle race in the SCM driver: we assign the __scm pointer before requesting the waitqueue interrupt. Assigning __scm marks the SCM API as ready to accept calls. It's possible that a user makes a call right after we set __scm and the firmware raises an interrupt before the driver's ready to service it. Move the __scm assignment after we request the interrupt. This has the added benefit of allowing us to drop the goto label. Signed-off-by: Bartosz Golaszewski --- drivers/firmware/qcom/qcom_scm.c | 29 ++++++++++------------------- 1 file changed, 10 insertions(+), 19 deletions(-) diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c index 561d4db7a847419fe5f9f034b09554de6a16a161..3d1532b9a5b4183f091b94b9f61395e661a50e2c 100644 --- a/drivers/firmware/qcom/qcom_scm.c +++ b/drivers/firmware/qcom/qcom_scm.c @@ -2270,24 +2270,21 @@ static int qcom_scm_probe(struct platform_device *pdev) return dev_err_probe(scm->dev, PTR_ERR(scm->mempool), "Failed to create the SCM memory pool\n"); - /* Paired with smp_load_acquire() in qcom_scm_is_available(). */ - smp_store_release(&__scm, scm); - irq = platform_get_irq_optional(pdev, 0); if (irq < 0) { - if (irq != -ENXIO) { - ret = irq; - goto err; - } + if (irq != -ENXIO) + return irq; } else { - ret = devm_request_threaded_irq(__scm->dev, irq, NULL, qcom_scm_irq_handler, - IRQF_ONESHOT, "qcom-scm", __scm); - if (ret < 0) { - dev_err_probe(scm->dev, ret, "Failed to request qcom-scm irq\n"); - goto err; - } + ret = devm_request_threaded_irq(scm->dev, irq, NULL, qcom_scm_irq_handler, + IRQF_ONESHOT, "qcom-scm", scm); + if (ret < 0) + return dev_err_probe(scm->dev, ret, + "Failed to request qcom-scm irq\n"); } + /* Paired with smp_load_acquire() in qcom_scm_is_available(). */ + smp_store_release(&__scm, scm); + __get_convention(); /* @@ -2317,12 +2314,6 @@ static int qcom_scm_probe(struct platform_device *pdev) WARN(ret < 0, "failed to initialize qseecom: %d\n", ret); return 0; - -err: - /* Paired with smp_load_acquire() in qcom_scm_is_available(). */ - smp_store_release(&__scm, NULL); - - return ret; } static void qcom_scm_shutdown(struct platform_device *pdev) -- 2.48.1