linux-kernel - [PATCH] rpmsg: char: return an error if device already open

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Date:   Wed, 6 Jan 2021 14:37:14 +0100
From:   Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>
CC:     <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <arnaud.pouliquen@...s.st.com>
Subject: [PATCH] rpmsg: char: return an error if device already open

The rpmsg_create_ept function is invoked when the device is opened.
As only one endpoint must be created per device. It is not
possible to open the same device twice.
The fix consists in returning -EBUSY when device is already
opened.

Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface")
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
---
 drivers/rpmsg/rpmsg_char.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 4bbbacdbf3bb..360a1ab0a9c4 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -127,6 +127,9 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
 	struct rpmsg_device *rpdev = eptdev->rpdev;
 	struct device *dev = &eptdev->dev;
 
+	if (eptdev->ept)
+		return -EBUSY;
+
 	get_device(dev);
 
 	ept = rpmsg_create_ept(rpdev, rpmsg_ept_cb, eptdev, eptdev->chinfo);
-- 
2.17.1