[PATCH] samples: rpmsg: Fix mtu printk specifiers

[Nathan Chancellor]

When building rpmsg_client_sample.c for a 32-bit platform, such as
during arm allmodconfig, there are a few warnings due to using an
incorrect specifier for mtu:

  samples/rpmsg/rpmsg_client_sample.c:68:59: error: format specifies type 'long' but the argument has type 'ssize_t' (aka 'int') [-Werror,-Wformat]
     68 |                 dev_warn(&rpdev->dev, "invalid rpmsg MTU size = %ld\n", mtu);
        |                                                                 ~~~     ^~~
        |                                                                 %zd
  ...
  samples/rpmsg/rpmsg_client_sample.c:72:50: error: format specifies type 'long' but the argument has type 'ssize_t' (aka 'int') [-Werror,-Wformat]
     72 |         dev_info(&rpdev->dev, "rpmsg MTU size = %ld\n", mtu);
        |                                                 ~~~     ^~~
        |                                                 %zd
  ...
  samples/rpmsg/rpmsg_client_sample.c:79:17: error: format specifies type 'long' but the argument has type 'ssize_t' (aka 'int') [-Werror,-Wformat]
     78 |                         "message size %zu exceeds rpmsg MTU size %ld\n",
        |                                                                  ~~~
        |                                                                  %zd
     79 |                         strlen(MSG), mtu);
        |                                      ^~~

Use '%zd', the proper specifier for a 'ssize_t' variable, to clear up
the warning. Additionally, modify the last dev_err() call in
rpmsg_sample_probe() to reuse msg_len instead of calling strlen(MSG)
again and use '%zd' throughout the string consistently.

Fixes: 1029c89bafc7 ("samples: rpmsg: Add MTU size info")
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
---
 samples/rpmsg/rpmsg_client_sample.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/samples/rpmsg/rpmsg_client_sample.c b/samples/rpmsg/rpmsg_client_sample.c
index 4c43436aadb6..8c629065c64c 100644
--- a/samples/rpmsg/rpmsg_client_sample.c
+++ b/samples/rpmsg/rpmsg_client_sample.c
@@ -65,18 +65,18 @@ static int rpmsg_sample_probe(struct rpmsg_device *rpdev)
 
 	mtu = rpmsg_get_mtu(rpdev->ept);
 	if (mtu < 0) {
-		dev_warn(&rpdev->dev, "invalid rpmsg MTU size = %ld\n", mtu);
+		dev_warn(&rpdev->dev, "invalid rpmsg MTU size = %zd\n", mtu);
 		return mtu;
 	}
 
-	dev_info(&rpdev->dev, "rpmsg MTU size = %ld\n", mtu);
+	dev_info(&rpdev->dev, "rpmsg MTU size = %zd\n", mtu);
 
 	msg_len = strlen(MSG);
 	/* make sure our message fits in a single rpmsg buffer */
 	if (msg_len > mtu) {
 		dev_err(&rpdev->dev,
-			"message size %zu exceeds rpmsg MTU size %ld\n",
-			strlen(MSG), mtu);
+			"message size %zd exceeds rpmsg MTU size %zd\n",
+			msg_len, mtu);
 		return -EMSGSIZE;
 	}
 

---
base-commit: 70e14d5db3a01a44f6c3217bb3dda2dd5828a507
change-id: 20260908-samples-rpmsg-fix-mtu-print-1903f03216ef

Best regards,
--  
Cheers,
Nathan