FAILED: patch "[PATCH] usb: gadget: f_uac2: fix return value for" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 9499327714de7bc5cf6c792112c1474932d8ad31
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024102111-sandstone-affected-1fd4@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9499327714de7bc5cf6c792112c1474932d8ad31 Mon Sep 17 00:00:00 2001
From: Kevin Groeneveld <[email protected]>
Date: Sun, 6 Oct 2024 19:26:31 -0400
Subject: [PATCH] usb: gadget: f_uac2: fix return value for
UAC2_ATTRIBUTE_STRING store

The configfs store callback should return the number of bytes consumed not the total number of bytes we actually stored. These could differ if for example the passed in string had a newline we did not store.

If the returned value does not match the number of bytes written the writer might assume a failure or keep trying to write the remaining bytes.

For example the following command will hang trying to write the final newline over and over again (tested on bash 2.05b):

echo foo > function_name

index 1cdda44455b3..ce5b77f89190 100644
@@ -2061,7 +2061,7 @@ static ssize_t f_uac2_opts_##name##_store(struct config_item *item,	\
 					  const char *page, size_t len)	\
 {									\
 	struct f_uac2_opts *opts = to_f_uac2_opts(item);		\
-	int ret = 0;							\
+	int ret = len;							\
 									\
 	mutex_lock(&opts->lock);					\
 	if (opts->refcnt) {						\

@@ -2072,8 +2072,8 @@ static ssize_t f_uac2_opts_##name##_store(struct config_item *item,	\
 	if (len && page[len - 1] == '\n')				\
 		len--;							\
 									\
-	ret = scnprintf(opts->name, min(sizeof(opts->name), len + 1),	\
-			"%s", page);					\
+	scnprintf(opts->name, min(sizeof(opts->name), len + 1),		\
+		  "%s", page);						\
 									\
 end:									\
 	mutex_unlock(&opts->lock);					\