Patch "mailbox: mailbox-test: don't rely on rx_buffer content to signal data ready" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    mailbox: mailbox-test: don't rely on rx_buffer content to signal data ready

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mailbox-mailbox-test-don-t-rely-on-rx_buffer-content-to-signal-data-ready.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Dec 12 10:32:42 CET 2017
From: Sudeep Holla <sudeep.holla@arm.com>
Date: Thu, 28 Sep 2017 11:18:53 +0100
Subject: mailbox: mailbox-test: don't rely on rx_buffer content to signal data ready

From: Sudeep Holla <sudeep.holla@arm.com>


[ Upstream commit e339c80af95e14de3712d69ddea09a3868fa14cd ]

Currently we rely on the first byte of the Rx buffer to check if there's
any data available to be read. If the first byte of the received buffer
is zero (i.e. null character), then we fail to signal that data is
available even when it's available.

Instead introduce a boolean variable to track the data availability and
update it in the channel receive callback as ready and clear it when the
data is read.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/mailbox/mailbox-test.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/mailbox/mailbox-test.c
+++ b/drivers/mailbox/mailbox-test.c
@@ -30,6 +30,7 @@
 #define MBOX_HEXDUMP_MAX_LEN	(MBOX_HEXDUMP_LINE_LEN *		\
 				 (MBOX_MAX_MSG_LEN / MBOX_BYTES_PER_LINE))
 
+static bool mbox_data_ready;
 static struct dentry *root_debugfs_dir;
 
 struct mbox_test_device {
@@ -152,16 +153,14 @@ out:
 
 static bool mbox_test_message_data_ready(struct mbox_test_device *tdev)
 {
-	unsigned char data;
+	bool data_ready;
 	unsigned long flags;
 
 	spin_lock_irqsave(&tdev->lock, flags);
-	data = tdev->rx_buffer[0];
+	data_ready = mbox_data_ready;
 	spin_unlock_irqrestore(&tdev->lock, flags);
 
-	if (data != '\0')
-		return true;
-	return false;
+	return data_ready;
 }
 
 static ssize_t mbox_test_message_read(struct file *filp, char __user *userbuf,
@@ -223,6 +222,7 @@ static ssize_t mbox_test_message_read(st
 	*(touser + l) = '\0';
 
 	memset(tdev->rx_buffer, 0, MBOX_MAX_MSG_LEN);
+	mbox_data_ready = false;
 
 	spin_unlock_irqrestore(&tdev->lock, flags);
 
@@ -292,6 +292,7 @@ static void mbox_test_receive_message(st
 				     message, MBOX_MAX_MSG_LEN);
 		memcpy(tdev->rx_buffer, message, MBOX_MAX_MSG_LEN);
 	}
+	mbox_data_ready = true;
 	spin_unlock_irqrestore(&tdev->lock, flags);
 
 	wake_up_interruptible(&tdev->waitq);


Patches currently in stable-queue which might be from sudeep.holla@arm.com are

queue-4.14/mailbox-mailbox-test-don-t-rely-on-rx_buffer-content-to-signal-data-ready.patch