linux-kernel - [PATCH 5.15 068/244] Input: exc3000 - fix return value check of wait_for_completion

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Date:   Tue, 23 Aug 2022 10:23:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Miaoqian Lin <linmq006@...il.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: [PATCH 5.15 068/244] Input: exc3000 - fix return value check of wait_for_completion_timeout

From: Miaoqian Lin <linmq006@...il.com>

commit 6bb7144c3fa16a5efb54a8e2aff1817b4168018e upstream.

wait_for_completion_timeout() returns unsigned long not int.
It returns 0 if timed out, and positive if completed.
The check for <= 0 is ambiguous and should be == 0 here
indicating timeout which is the only error case.

Fixes: 102feb1ddfd0 ("Input: exc3000 - factor out vendor data request")
Signed-off-by: Miaoqian Lin <linmq006@...il.com>
Link: https://lore.kernel.org/r/20220411105828.22140-1-linmq006@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/input/touchscreen/exc3000.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/input/touchscreen/exc3000.c
+++ b/drivers/input/touchscreen/exc3000.c
@@ -220,6 +220,7 @@ static int exc3000_vendor_data_request(s
 {
 	u8 buf[EXC3000_LEN_VENDOR_REQUEST] = { 0x67, 0x00, 0x42, 0x00, 0x03 };
 	int ret;
+	unsigned long time_left;
 
 	mutex_lock(&data->query_lock);
 
@@ -233,9 +234,9 @@ static int exc3000_vendor_data_request(s
 		goto out_unlock;
 
 	if (response) {
-		ret = wait_for_completion_timeout(&data->wait_event,
-						  timeout * HZ);
-		if (ret <= 0) {
+		time_left = wait_for_completion_timeout(&data->wait_event,
+							timeout * HZ);
+		if (time_left == 0) {
 			ret = -ETIMEDOUT;
 			goto out_unlock;
 		}