linux-kernel - [PATCH] staging: most: video: improve arguments to copy_to

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Message-ID: <aJx6OF6L2Nza9zQ0@bhairav-test.ee.iitb.ac.in>
Date: Wed, 13 Aug 2025 17:12:48 +0530
From: Akhilesh Patil <akhilesh@...iitb.ac.in>
To: parthiban.veerasooran@...rochip.com, christian.gromm@...rochip.com,
	gregkh@...uxfoundation.org
Cc: linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
	akhileshpatilvnit@...il.com, skhan@...uxfoundation.org
Subject: [PATCH] staging: most: video: improve arguments to copy_to_user()

Define cnt constant as unsigned long as expected by copy_to_user()
to avoid implicit type conversion. Define rem constant as unsigned long
to compare it with the same type size_t of count variable.
Use standard helper min() to carry out careful comparison to achive
same functionality.

Signed-off-by: Akhilesh Patil <akhilesh@...iitb.ac.in>
---
This patch is motivated from coccinelle report which suggested to use
kernel standard helper min(). During build check, I found that
comparison max()  showing error while comparing variables of
different types. Hence this patch also fixes that to make comparison of
save types.

Compile tested only.
---
 drivers/staging/most/video/video.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/most/video/video.c b/drivers/staging/most/video/video.c
index 2b3cdb1ce140..4b15c390c32d 100644
--- a/drivers/staging/most/video/video.c
+++ b/drivers/staging/most/video/video.c
@@ -172,8 +172,8 @@ static ssize_t comp_vdev_read(struct file *filp, char __user *buf,
 
 	while (count > 0 && data_ready(mdev)) {
 		struct mbo *const mbo = get_top_mbo(mdev);
-		int const rem = mbo->processed_length - fh->offs;
-		int const cnt = rem < count ? rem : count;
+		unsigned long const rem = mbo->processed_length - fh->offs;
+		unsigned long const cnt = min(rem, count);
 
 		if (copy_to_user(buf, mbo->virt_address + fh->offs, cnt)) {
 			v4l2_err(&mdev->v4l2_dev, "read: copy_to_user failed\n");
-- 
2.34.1