linux-kernel - [PATCH] usb: dwc2: gadget: Fix a warning when compiling with W=1

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Message-Id: <5cf603809388aa04c9a02bbfe3cf531c20bb043e.1695466447.git.christophe.jaillet@wanadoo.fr>
Date:   Sat, 23 Sep 2023 12:54:24 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Minas Harutyunyan <hminas@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ben Dooks <ben@...tec.co.uk>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Greg Kroah-Hartman <gregkh@...e.de>, linux-usb@...r.kernel.org
Subject: [PATCH] usb: dwc2: gadget: Fix a warning when compiling with W=1

In order to teach the compiler that 'hs_ep->name' will never be truncated,
we need to tell it that 'epnum' is not negative.

'epnum' comes from in a 'for' loop in dwc2_gadget_init(), starting at 0
and ending at 255. (hsotg->num_of_eps is a char)

When building with W=1, this fixes the following warnings:

  drivers/usb/dwc2/gadget.c: In function ‘dwc2_hsotg_initep’:
  drivers/usb/dwc2/gadget.c:4804:55: error: ‘%d’ directive output may be truncated writing between 1 and 11 bytes into a region of size 8 [-Werror=format-truncation=]
   4804 |         snprintf(hs_ep->name, sizeof(hs_ep->name), "ep%d%s", epnum, dir);
        |                                                       ^~
  drivers/usb/dwc2/gadget.c:4804:52: note: directive argument in the range [-2147483645, 255]
   4804 |         snprintf(hs_ep->name, sizeof(hs_ep->name), "ep%d%s", epnum, dir);
        |                                                    ^~~~~~~~
  drivers/usb/dwc2/gadget.c:4804:9: note: ‘snprintf’ output between 6 and 17 bytes into a destination of size 10
   4804 |         snprintf(hs_ep->name, sizeof(hs_ep->name), "ep%d%s", epnum, dir);
        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 5b7d70c6dbf2 ("USB: Gadget driver for Samsung HS/OtG block")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Only changing:
  -	int epnum;
  +	unsigned int epnum;
is enought to fix the build warning.

But changing the prototype of dwc2_hsotg_initep() and the printf() format
as well, to make obvious that epnum is >= 0, looks more logical to me.
---
 drivers/usb/dwc2/gadget.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index b517a7216de2..102b2dd8113e 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -4786,8 +4786,8 @@ static const struct usb_gadget_ops dwc2_hsotg_gadget_ops = {
  */
 static void dwc2_hsotg_initep(struct dwc2_hsotg *hsotg,
 			      struct dwc2_hsotg_ep *hs_ep,
-				       int epnum,
-				       bool dir_in)
+			      unsigned int epnum,
+			      bool dir_in)
 {
 	char *dir;
 
@@ -4801,7 +4801,7 @@ static void dwc2_hsotg_initep(struct dwc2_hsotg *hsotg,
 	hs_ep->dir_in = dir_in;
 	hs_ep->index = epnum;
 
-	snprintf(hs_ep->name, sizeof(hs_ep->name), "ep%d%s", epnum, dir);
+	snprintf(hs_ep->name, sizeof(hs_ep->name), "ep%u%s", epnum, dir);
 
 	INIT_LIST_HEAD(&hs_ep->queue);
 	INIT_LIST_HEAD(&hs_ep->ep.ep_list);
@@ -4965,7 +4965,7 @@ static void dwc2_hsotg_dump(struct dwc2_hsotg *hsotg)
 int dwc2_gadget_init(struct dwc2_hsotg *hsotg)
 {
 	struct device *dev = hsotg->dev;
-	int epnum;
+	unsigned int epnum;
 	int ret;
 
 	/* Dump fifo information */
-- 
2.34.1