linux-kernel - [PATCH -next] driver core: fix deadlock in __driver

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Date:   Wed, 8 Jun 2022 17:43:55 +0800
From:   Zhang Wensheng <zhangwensheng5@...wei.com>
To:     <gregkh@...uxfoundation.org>, <rafael@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <yukuai3@...wei.com>,
        <zhangwensheng5@...wei.com>
Subject: [PATCH -next] driver core: fix deadlock in __driver_attach

In __driver_attach function, There are also potential AA deadlock
problem, like the commit b232b02bf3c2 ("driver core: fix deadlock
in __device_attach").

Fixes: ef0ff68351be ("driver core: Probe devices asynchronously instead of the driver")
Signed-off-by: Zhang Wensheng <zhangwensheng5@...wei.com>
---
 drivers/base/dd.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 11b0fb6414d3..b766968a873c 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -1115,6 +1115,7 @@ static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
 static int __driver_attach(struct device *dev, void *data)
 {
 	struct device_driver *drv = data;
+	bool async = false;
 	int ret;
 
 	/*
@@ -1153,9 +1154,11 @@ static int __driver_attach(struct device *dev, void *data)
 		if (!dev->driver && !dev->p->async_driver) {
 			get_device(dev);
 			dev->p->async_driver = drv;
-			async_schedule_dev(__driver_attach_async_helper, dev);
+			async = true;
 		}
 		device_unlock(dev);
+		if (async)
+			async_schedule_dev(__driver_attach_async_helper, dev);
 		return 0;
 	}
 
-- 
2.31.1