linux-kernel - [PATCH] extcon: Remove potential problem of extcon_register

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Date:   Mon, 19 Dec 2016 21:14:34 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     linux-kernel@...r.kernel.org
Cc:     cw00.choi@...sung.com, chanwoo@...nel.org, myungjoo.ham@...sung.com
Subject: [PATCH] extcon: Remove potential problem of extcon_register_notifier()
 when edev parameter is NULL

This patch removes the potential problem of extcon_register_notifier()
when edev parameter is NULL. When edev is NULL, this function returns
the first extcon device which includes the sepecific external connector
of second paramter. But, it don't guarantee the same operation in all cases.
To remove this confusion and potential problem, this patch fixes it.

Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
---
 drivers/extcon/extcon.c | 33 +++++++--------------------------
 1 file changed, 7 insertions(+), 26 deletions(-)

diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
index 7c1e3a7b14e0..d0e367959c91 100644
--- a/drivers/extcon/extcon.c
+++ b/drivers/extcon/extcon.c
@@ -906,35 +906,16 @@ int extcon_register_notifier(struct extcon_dev *edev, unsigned int id,
 	unsigned long flags;
 	int ret, idx = -EINVAL;
 
-	if (!nb)
+	if (!edev || !nb)
 		return -EINVAL;
 
-	if (edev) {
-		idx = find_cable_index_by_id(edev, id);
-		if (idx < 0)
-			return idx;
-
-		spin_lock_irqsave(&edev->lock, flags);
-		ret = raw_notifier_chain_register(&edev->nh[idx], nb);
-		spin_unlock_irqrestore(&edev->lock, flags);
-	} else {
-		struct extcon_dev *extd;
-
-		mutex_lock(&extcon_dev_list_lock);
-		list_for_each_entry(extd, &extcon_dev_list, entry) {
-			idx = find_cable_index_by_id(extd, id);
-			if (idx >= 0)
-				break;
-		}
-		mutex_unlock(&extcon_dev_list_lock);
+	idx = find_cable_index_by_id(edev, id);
+	if (idx < 0)
+		return idx;
 
-		if (idx >= 0) {
-			edev = extd;
-			return extcon_register_notifier(extd, id, nb);
-		} else {
-			ret = -ENODEV;
-		}
-	}
+	spin_lock_irqsave(&edev->lock, flags);
+	ret = raw_notifier_chain_register(&edev->nh[idx], nb);
+	spin_unlock_irqrestore(&edev->lock, flags);
 
 	return ret;
 }
-- 
1.9.1