linux-kernel - [PATCH v2 2/6] mailbox: don't protect of_parse_phandle_with_args with con

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Message-Id: <20250224-mbox-mutex-v2-2-9d699148fe4e@linaro.org>
Date: Mon, 24 Feb 2025 08:27:14 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Jassi Brar <jassisinghbrar@...il.com>
Cc: linux-kernel@...r.kernel.org, andre.draszik@...aro.org, 
 peter.griffin@...aro.org, willmcvicker@...gle.com, kernel-team@...roid.com, 
 Tudor Ambarus <tudor.ambarus@...aro.org>
Subject: [PATCH v2 2/6] mailbox: don't protect of_parse_phandle_with_args
 with con_mutex

There are no concurrency problems if multiple consumers parse the
phandle, don't gratuiously protect the parsing with the mutex used
for the controllers list.

Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
---
 drivers/mailbox/mailbox.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index cb174e788a96..784b56859a06 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -413,16 +413,15 @@ struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
 		return ERR_PTR(-ENODEV);
 	}
 
-	mutex_lock(&con_mutex);
-
 	ret = of_parse_phandle_with_args(dev->of_node, "mboxes", "#mbox-cells",
 					 index, &spec);
 	if (ret) {
 		dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
-		mutex_unlock(&con_mutex);
 		return ERR_PTR(ret);
 	}
 
+	mutex_lock(&con_mutex);
+
 	chan = ERR_PTR(-EPROBE_DEFER);
 	list_for_each_entry(mbox, &mbox_cons, node)
 		if (mbox->dev->of_node == spec.np) {

-- 
2.48.1.601.g30ceb7b040-goog