linux-kernel - [PATCH] driver-core: remove lock for platform devices during probe

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Message-Id: <1493012536-9240-1-git-send-email-weili@codeaurora.org>
Date:   Mon, 24 Apr 2017 13:42:16 +0800
From:   Wei Li <weili@...eaurora.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, vatsa@...eaurora.org,
        Wei Li <weili@...eaurora.org>
Subject: [PATCH] driver-core: remove lock for platform devices during probe

During driver probe procedure, lock on the parent of
platform devices could be removed to make probe in
parallel.

Signed-off-by: Wei Li <weili@...eaurora.org>
---
 drivers/base/dd.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index a1fbf55..e238fbc 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -25,6 +25,7 @@
 #include <linux/async.h>
 #include <linux/pm_runtime.h>
 #include <linux/pinctrl/devinfo.h>
+#include <linux/platform_device.h>
 
 #include "base.h"
 #include "power/power.h"
@@ -749,13 +750,14 @@ static int __driver_attach(struct device *dev, void *data)
 		return ret;
 	} /* ret > 0 means positive match */
 
-	if (dev->parent)	/* Needed for USB */
+	if (dev->parent &&
+		(dev->bus != &platform_bus_type))	/* Needed for USB */
 		device_lock(dev->parent);
 	device_lock(dev);
 	if (!dev->driver)
 		driver_probe_device(drv, dev);
 	device_unlock(dev);
-	if (dev->parent)
+	if (dev->parent && (dev->bus != &platform_bus_type))
 		device_unlock(dev->parent);
 
 	return 0;
-- 
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