FAILED: patch "[PATCH] ACPI: NFIT: core: Fix possible deadlock and missing" failed to apply to 7.1-stable tree

index aaa84ae7a20e..cb771d9cadb2 100644
@@ -56,6 +56,8 @@ MODULE_PARM_DESC(force_labels, "Opt-in to labels despite missing methods");
 LIST_HEAD(acpi_descs);
 DEFINE_MUTEX(acpi_desc_lock);
 
+DEFINE_MUTEX(acpi_notify_lock);
+
 static struct workqueue_struct *nfit_wq;
 
 struct nfit_table_prev {

@@ -1708,9 +1710,15 @@ static void acpi_nvdimm_notify(acpi_handle handle, u32 event, void *data)
 	struct acpi_device *adev = data;
 	struct device *dev = &adev->dev;
 
-	device_lock(dev->parent);
+	/*
+	 * Locking is needed here for synchronization with driver probe and
+	 * removal and the parent's driver data pointer is NULL when teardown
+	 * is in progress (while the parent here is expected to be the ACPI
+	 * companion of the platform device used for driver binding).
+	 */
+	guard(mutex)(&acpi_notify_lock);
+
 	__acpi_nvdimm_notify(dev, event);
-	device_unlock(dev->parent);
 }
 
 static bool acpi_nvdimm_has_method(struct acpi_device *adev, char *method)

@@ -3156,11 +3164,10 @@ EXPORT_SYMBOL_GPL(acpi_nfit_init);
 static int acpi_nfit_flush_probe(struct nvdimm_bus_descriptor *nd_desc)
 {
 	struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
-	struct device *dev = acpi_desc->dev;
 
-	/* Bounce the device lock to flush acpi_nfit_add / acpi_nfit_notify */
-	device_lock(dev);
-	device_unlock(dev);
+	/* Bounce the notify lock to flush acpi_nfit_probe / acpi_nfit_notify */
+	mutex_lock(&acpi_notify_lock);
+	mutex_unlock(&acpi_notify_lock);
 
 	/* Bounce the init_mutex to complete initial registration */
 	mutex_lock(&acpi_desc->init_mutex);

@@ -3292,10 +3299,17 @@ static void acpi_nfit_put_table(void *table)
 static void acpi_nfit_notify(acpi_handle handle, u32 event, void *data)
 {
 	struct device *dev = data;
+	struct acpi_device *adev = ACPI_COMPANION(dev);
 
-	device_lock(dev);
-	__acpi_nfit_notify(dev, handle, event);
-	device_unlock(dev);
+	/*
+	 * Locking is needed here for synchronization with driver probe and
+	 * removal and the ACPI companion's driver data pointer is NULL when
+	 * teardown is in progress.
+	 */
+	guard(mutex)(&acpi_notify_lock);
+
+	if (dev_get_drvdata(&adev->dev))
+		__acpi_nfit_notify(dev, handle, event);
 }
 
 void acpi_nfit_shutdown(void *data)

@@ -3337,11 +3351,18 @@ static int acpi_nfit_probe(struct platform_device *pdev)
 	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
 	struct acpi_nfit_desc *acpi_desc;
 	struct device *dev = &pdev->dev;
+	struct acpi_device *adev = ACPI_COMPANION(dev);
 	struct acpi_table_header *tbl;
 	acpi_status status = AE_OK;
 	acpi_size sz;
 	int rc = 0;
 
+	/*
+	 * Prevent acpi_nfit_notify() from progressing until the probe is
+	 * complete in case there is a concurrent event to process.
+	 */
+	guard(mutex)(&acpi_notify_lock);
+
 	rc = devm_acpi_install_notify_handler(dev, ACPI_DEVICE_NOTIFY,
 					      acpi_nfit_notify, dev);
 	if (rc)

@@ -3357,6 +3378,11 @@ static int acpi_nfit_probe(struct platform_device *pdev)
 		 * data in the format of a series of NFIT Structures.
 		 */
 		dev_dbg(dev, "failed to find NFIT at startup\n");
+		/*
+		 * Let acpi_nfit_update_notify() run in case it will need to
+		 * allocate the acpi_desc object.
+		 */
+		dev_set_drvdata(&adev->dev, dev);
 		return 0;
 	}
 

@@ -3374,7 +3400,7 @@ static int acpi_nfit_probe(struct platform_device *pdev)
 	acpi_desc->acpi_header = *tbl;
 
 	/* Evaluate _FIT and override with that if present */
-	status = acpi_evaluate_object(ACPI_HANDLE(dev), "_FIT", NULL, &buf);
+	status = acpi_evaluate_object(adev->handle, "_FIT", NULL, &buf);
 	if (ACPI_SUCCESS(status) && buf.length > 0) {
 		union acpi_object *obj = buf.pointer;
 

@@ -3391,14 +3417,27 @@ static int acpi_nfit_probe(struct platform_device *pdev)
 				+ sizeof(struct acpi_table_nfit),
 				sz - sizeof(struct acpi_table_nfit));
 
-	if (rc)
+	if (rc) {
 		acpi_nfit_shutdown(acpi_desc);
+		return rc;
+	}
 
-	return rc;
+	/*
+	 * Let notify handlers operate (the actual value of the ACPI companion's
+	 * driver data pointer does not matter here so long as it is not NULL).
+	 */
+	dev_set_drvdata(&adev->dev, dev);
+	return 0;
 }
 
 static void acpi_nfit_remove(struct platform_device *pdev)
 {
+	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
+
+	guard(mutex)(&acpi_notify_lock);
+
+	/* Make notify handlers bail out early going forward. */
+	dev_set_drvdata(&adev->dev, NULL);
 	acpi_nfit_shutdown(platform_get_drvdata(pdev));
 }
 

index 9304ac996d41ad..1c592a01d825d5 100644
@@ -56,6 +56,8 @@ MODULE_PARM_DESC(force_labels, "Opt-in to labels despite missing methods");
 LIST_HEAD(acpi_descs);
 DEFINE_MUTEX(acpi_desc_lock);
 
+DEFINE_MUTEX(acpi_notify_lock);
+
 static struct workqueue_struct *nfit_wq;
 
 struct nfit_table_prev {

@@ -1710,9 +1712,15 @@ static void acpi_nvdimm_notify(acpi_handle handle, u32 event, void *data)
 	struct acpi_device *adev = data;
 	struct device *dev = &adev->dev;
 
-	device_lock(dev->parent);
+	/*
+	 * Locking is needed here for synchronization with driver probe and
+	 * removal and the parent's driver data pointer is NULL when teardown
+	 * is in progress (while the parent here is expected to be the ACPI
+	 * companion of the platform device used for driver binding).
+	 */
+	guard(mutex)(&acpi_notify_lock);
+
 	__acpi_nvdimm_notify(dev, event);
-	device_unlock(dev->parent);
 }
 
 static bool acpi_nvdimm_has_method(struct acpi_device *adev, char *method)

@@ -3156,11 +3164,10 @@ EXPORT_SYMBOL_GPL(acpi_nfit_init);
 static int acpi_nfit_flush_probe(struct nvdimm_bus_descriptor *nd_desc)
 {
 	struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
-	struct device *dev = acpi_desc->dev;
 
-	/* Bounce the device lock to flush acpi_nfit_add / acpi_nfit_notify */
-	device_lock(dev);
-	device_unlock(dev);
+	/* Bounce the notify lock to flush acpi_nfit_probe / acpi_nfit_notify */
+	mutex_lock(&acpi_notify_lock);
+	mutex_unlock(&acpi_notify_lock);
 
 	/* Bounce the init_mutex to complete initial registration */
 	mutex_lock(&acpi_desc->init_mutex);

@@ -3292,10 +3299,17 @@ static void acpi_nfit_put_table(void *table)
 static void acpi_nfit_notify(acpi_handle handle, u32 event, void *data)
 {
 	struct device *dev = data;
+	struct acpi_device *adev = ACPI_COMPANION(dev);
 
-	device_lock(dev);
-	__acpi_nfit_notify(dev, handle, event);
-	device_unlock(dev);
+	/*
+	 * Locking is needed here for synchronization with driver probe and
+	 * removal and the ACPI companion's driver data pointer is NULL when
+	 * teardown is in progress.
+	 */
+	guard(mutex)(&acpi_notify_lock);
+
+	if (dev_get_drvdata(&adev->dev))
+		__acpi_nfit_notify(dev, handle, event);
 }
 
 static void acpi_nfit_remove_notify_handler(void *data)

@@ -3310,6 +3324,20 @@ void acpi_nfit_shutdown(void *data)
 {
 	struct acpi_nfit_desc *acpi_desc = data;
 	struct device *bus_dev = to_nvdimm_bus_dev(acpi_desc->nvdimm_bus);
+	struct acpi_device *adev = ACPI_COMPANION(acpi_desc->dev);
+
+	/*
+	 * Make notify handlers bail out early going forward.  The driver
+	 * data pointer of the ACPI companion is only set once probing has
+	 * succeeded, so it is still NULL when this runs from a failing
+	 * probe, which also holds acpi_notify_lock, in which case the lock
+	 * must not be acquired here.
+	 */
+	if (adev && dev_get_drvdata(&adev->dev)) {
+		mutex_lock(&acpi_notify_lock);
+		dev_set_drvdata(&adev->dev, NULL);
+		mutex_unlock(&acpi_notify_lock);
+	}
 
 	/*
 	 * Destruct under acpi_desc_lock so that nfit_handle_mce does not

@@ -3341,16 +3369,21 @@ static int acpi_nfit_probe(struct platform_device *pdev)
 	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
 	struct acpi_nfit_desc *acpi_desc;
 	struct device *dev = &pdev->dev;
+	struct acpi_device *adev = ACPI_COMPANION(dev);
 	struct acpi_table_header *tbl;
-	struct acpi_device *adev;
 	acpi_status status = AE_OK;
 	acpi_size sz;
 	int rc = 0;
 
-	adev = ACPI_COMPANION(&pdev->dev);
 	if (!adev)
 		return -ENODEV;
 
+	/*
+	 * Prevent acpi_nfit_notify() from progressing until the probe is
+	 * complete in case there is a concurrent event to process.
+	 */
+	guard(mutex)(&acpi_notify_lock);
+
 	rc = acpi_dev_install_notify_handler(adev, ACPI_DEVICE_NOTIFY,
 					     acpi_nfit_notify, dev);
 	if (rc)

@@ -3371,6 +3404,11 @@ static int acpi_nfit_probe(struct platform_device *pdev)
 		 * data in the format of a series of NFIT Structures.
 		 */
 		dev_dbg(dev, "failed to find NFIT at startup\n");
+		/*
+		 * Let acpi_nfit_update_notify() run in case it will need to
+		 * allocate the acpi_desc object.
+		 */
+		dev_set_drvdata(&adev->dev, dev);
 		return 0;
 	}
 

@@ -3408,7 +3446,16 @@ static int acpi_nfit_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
-	return devm_add_action_or_reset(dev, acpi_nfit_shutdown, acpi_desc);
+	rc = devm_add_action_or_reset(dev, acpi_nfit_shutdown, acpi_desc);
+	if (rc)
+		return rc;
+
+	/*
+	 * Let notify handlers operate (the actual value of the ACPI companion's
+	 * driver data pointer does not matter here so long as it is not NULL).
+	 */
+	dev_set_drvdata(&adev->dev, dev);
+	return 0;
 }
 
 static void acpi_nfit_update_notify(struct device *dev, acpi_handle handle)