linux-kernel - [PATCH 1/3] driver core: Introduce helper function __device_attach_driver

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Message-Id: <20260107175548.1792-2-guojinhui.liam@bytedance.com>
Date: Thu,  8 Jan 2026 01:55:46 +0800
From: "Jinhui Guo" <guojinhui.liam@...edance.com>
To: <dakr@...nel.org>, <alexander.h.duyck@...ux.intel.com>, 
	<alexanderduyck@...com>, <bhelgaas@...gle.com>, <bvanassche@....org>, 
	<dan.j.williams@...el.com>, <gregkh@...uxfoundation.org>, 
	<helgaas@...nel.org>, <rafael@...nel.org>, <tj@...nel.org>
Cc: <guojinhui.liam@...edance.com>, <linux-kernel@...r.kernel.org>, 
	<linux-pci@...r.kernel.org>
Subject: [PATCH 1/3] driver core: Introduce helper function __device_attach_driver_scan()

Introduce a helper to eliminate duplication between
__device_attach() and __device_attach_async_helper();
a later patch will reuse it to add NUMA-node awareness
to the synchronous probe path in __device_attach().

No functional changes.

Signed-off-by: Jinhui Guo <guojinhui.liam@...edance.com>
---
 drivers/base/dd.c | 71 ++++++++++++++++++++++++++---------------------
 1 file changed, 40 insertions(+), 31 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 349f31bedfa1..896f98add97d 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -962,6 +962,44 @@ static int __device_attach_driver(struct device_driver *drv, void *_data)
 	return ret == 0;
 }
 
+static int __device_attach_driver_scan(struct device_attach_data *data,
+				       bool *need_async)
+{
+	int ret = 0;
+	struct device *dev = data->dev;
+
+	if (dev->parent)
+		pm_runtime_get_sync(dev->parent);
+
+	ret = bus_for_each_drv(dev->bus, NULL, data,
+			       __device_attach_driver);
+	/*
+	 * When running in an async worker, a NULL need_async is passed
+	 * since we are already in an async worker.
+	 */
+	if (need_async && !ret && data->check_async && data->have_async) {
+		/*
+		 * If we could not find appropriate driver
+		 * synchronously and we are allowed to do
+		 * async probes and there are drivers that
+		 * want to probe asynchronously, we'll
+		 * try them.
+		 */
+		dev_dbg(dev, "scheduling asynchronous probe\n");
+		get_device(dev);
+		*need_async = true;
+	} else {
+		if (!need_async)
+			dev_dbg(dev, "async probe completed\n");
+		pm_request_idle(dev);
+	}
+
+	if (dev->parent)
+		pm_runtime_put(dev->parent);
+
+	return ret;
+}
+
 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 {
 	struct device *dev = _dev;
@@ -982,16 +1020,8 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 	if (dev->p->dead || dev->driver)
 		goto out_unlock;
 
-	if (dev->parent)
-		pm_runtime_get_sync(dev->parent);
+	__device_attach_driver_scan(&data, NULL);
 
-	bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
-	dev_dbg(dev, "async probe completed\n");
-
-	pm_request_idle(dev);
-
-	if (dev->parent)
-		pm_runtime_put(dev->parent);
 out_unlock:
 	device_unlock(dev);
 
@@ -1025,28 +1055,7 @@ static int __device_attach(struct device *dev, bool allow_async)
 			.want_async = false,
 		};
 
-		if (dev->parent)
-			pm_runtime_get_sync(dev->parent);
-
-		ret = bus_for_each_drv(dev->bus, NULL, &data,
-					__device_attach_driver);
-		if (!ret && allow_async && data.have_async) {
-			/*
-			 * If we could not find appropriate driver
-			 * synchronously and we are allowed to do
-			 * async probes and there are drivers that
-			 * want to probe asynchronously, we'll
-			 * try them.
-			 */
-			dev_dbg(dev, "scheduling asynchronous probe\n");
-			get_device(dev);
-			async = true;
-		} else {
-			pm_request_idle(dev);
-		}
-
-		if (dev->parent)
-			pm_runtime_put(dev->parent);
+		ret = __device_attach_driver_scan(&data, &async);
 	}
 out_unlock:
 	device_unlock(dev);
-- 
2.20.1