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

[<gregkh@linuxfoundation.org>]

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 <stable@vger.kernel.org>.

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 '<stable@vger.kernel.org>' --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 <kgroeneveld@lenbrook.com>
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

Fixes: 993a44fa85c1 ("usb: gadget: f_uac2: allow changing interface name via configfs")
Cc: stable <stable@kernel.org>
Signed-off-by: Kevin Groeneveld <kgroeneveld@lenbrook.com>
Link: https://lore.kernel.org/r/20241006232637.4267-1-kgroeneveld@lenbrook.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index 1cdda44455b3..ce5b77f89190 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -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);					\