[PATCH] cw1200: fix bogus maybe-uninitialized warning

[PATCH] cw1200: fix bogus maybe-uninitialized warning

[Arnd Bergmann]

On x86, the cw1200 driver produces a rather silly warning about the
possible use of the 'ret' variable without an initialization
presumably after being confused by the architecture specific definition
of WARN_ON:

drivers/net/wireless/st/cw1200/wsm.c: In function ‘wsm_handle_rx’:
drivers/net/wireless/st/cw1200/wsm.c:1457:9: error: ‘ret’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

As the driver just checks the same variable twice here, we can simplify
it by removing the second condition, which makes it more readable and
avoids the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/wireless/st/cw1200/wsm.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/st/cw1200/wsm.c b/drivers/net/wireless/st/cw1200/wsm.c
index 680d60eabc75..094e6637ade2 100644
--- a/drivers/net/wireless/st/cw1200/wsm.c
+++ b/drivers/net/wireless/st/cw1200/wsm.c
@@ -385,14 +385,13 @@ static int wsm_multi_tx_confirm(struct cw1200_common *priv,
 	if (WARN_ON(count <= 0))
 		return -EINVAL;
 
-	if (count > 1) {
-		/* We already released one buffer, now for the rest */
-		ret = wsm_release_tx_buffer(priv, count - 1);
-		if (ret < 0)
-			return ret;
-		else if (ret > 0)
-			cw1200_bh_wakeup(priv);
-	}
+	/* We already released one buffer, now for the rest */
+	ret = wsm_release_tx_buffer(priv, count - 1);
+	if (ret < 0)
+		return ret;
+
+	if (ret > 0)
+		cw1200_bh_wakeup(priv);
 
 	cw1200_debug_txed_multi(priv, count);
 	for (i = 0; i < count; ++i) {
-- 
2.9.0

RE: [PATCH] cw1200: fix bogus maybe-uninitialized warning

[David Laight]
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==

Re: [PATCH] cw1200: fix bogus maybe-uninitialized warning

[Solomon Peachy]

[-- Attachment #1: Type: text/plain, Size: 839 bytes --]

On Tue, Oct 25, 2016 at 01:24:55PM +0000, David Laight wrote:
> > -	if (count > 1) {
> > -		/* We already released one buffer, now for the rest */
> > -		ret = wsm_release_tx_buffer(priv, count - 1);
> > -		if (ret < 0)
> > -			return ret;
> > -		else if (ret > 0)
> > -			cw1200_bh_wakeup(priv);
> > -	}
> > +	/* We already released one buffer, now for the rest */
> > +	ret = wsm_release_tx_buffer(priv, count - 1);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	if (ret > 0)
> > +		cw1200_bh_wakeup(priv);
> 
> That doesn't look equivalent to me (when count == 1).

I concur, this patch should not be applied in its current form.

 - Solomon
-- 
Solomon Peachy        		       pizza at shaftnet dot org
Delray Beach, FL                          ^^ (email/xmpp) ^^
Quidquid latine dictum sit, altum viditur.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 163 bytes --]

Re: [PATCH] cw1200: fix bogus maybe-uninitialized warning

[Arnd Bergmann]

On Tuesday, October 25, 2016 1:24:55 PM CEST David Laight wrote:
> > diff --git a/drivers/net/wireless/st/cw1200/wsm.c b/drivers/net/wireless/st/cw1200/wsm.c
> > index 680d60eabc75..094e6637ade2 100644
> > --- a/drivers/net/wireless/st/cw1200/wsm.c
> > +++ b/drivers/net/wireless/st/cw1200/wsm.c
> > @@ -385,14 +385,13 @@ static int wsm_multi_tx_confirm(struct cw1200_common *priv,
> >       if (WARN_ON(count <= 0))
> >               return -EINVAL;
> > 
> > -     if (count > 1) {
> > -             /* We already released one buffer, now for the rest */
> > -             ret = wsm_release_tx_buffer(priv, count - 1);
> > -             if (ret < 0)
> > -                     return ret;
> > -             else if (ret > 0)
> > -                     cw1200_bh_wakeup(priv);
> > -     }
> > +     /* We already released one buffer, now for the rest */
> > +     ret = wsm_release_tx_buffer(priv, count - 1);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     if (ret > 0)
> > +             cw1200_bh_wakeup(priv);
> 
> That doesn't look equivalent to me (when count == 1).

Ah, that's what I missed, thanks for pointing that out!

> > 
> >       cw1200_debug_txed_multi(priv, count);
> >       for (i = 0; i < count; ++i) {
> 
> Convert this loop into a do ... while so the body executes at least once.

Good idea. Version 2 coming now.

	Arnd