diff mbox series

usb: gadget: f_uac2: fix return value for UAC2_ATTRIBUTE_STRING store

Message ID 20241006232637.4267-1-kgroeneveld@lenbrook.com (mailing list archive)
State Accepted
Commit 9499327714de7bc5cf6c792112c1474932d8ad31
Headers show
Series usb: gadget: f_uac2: fix return value for UAC2_ATTRIBUTE_STRING store | expand

Commit Message

Kevin Groeneveld Oct. 6, 2024, 11:26 p.m. UTC 
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")
Signed-off-by: Kevin Groeneveld <kgroeneveld@lenbrook.com>
---
 drivers/usb/gadget/function/f_uac2.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
diff mbox series

Patch

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);					\