[PATCH] usb: renesas_usbhs: avoid uninitialized variable use

[PATCH] usb: renesas_usbhs: avoid uninitialized variable use

[Arnd Bergmann]

After the renesas_usbhs driver is enabled in ARM multi_v7_defconfig,
we now get a new warning:

renesas_usbhs/mod.c: In function 'usbhs_interrupt':
renesas_usbhs/mod.c:246:7: warning: 'intenb1' may be used uninitialized in this function [-Wmaybe-uninitialized]

gcc correctly points to a problem here, for the case that the
device is in host mode, we use the intenb1 variable without
having assigned it first. The state->intsts1 has a similar
problem, but gcc cannot know that.

This avoids the problem by initializing both sides of the
comparison to zero when we don't read them from the respective
registers.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 88a25e02f3 ("usb: renesas_usbhs: Add access control for INTSTS1 and INTENB1 register")

diff --git a/drivers/usb/renesas_usbhs/mod.c b/drivers/usb/renesas_usbhs/mod.c
index e5ce6e6d4f51..d4be5d594896 100644
--- a/drivers/usb/renesas_usbhs/mod.c
+++ b/drivers/usb/renesas_usbhs/mod.c
@@ -223,6 +223,8 @@ static int usbhs_status_get_each_irq(struct usbhs_priv *priv,
 	if (usbhs_mod_is_host(priv)) {
 		state->intsts1 = usbhs_read(priv, INTSTS1);
 		intenb1 = usbhs_read(priv, INTENB1);
+	} else {
+		state->intsts1 = intenb1 = 0;
 	}
 
 	/* mask */

[PATCH] usb: renesas_usbhs: avoid uninitialized variable use

[Yoshihiro Shimoda]

Hi Arnd,

> Sent: Friday, May 22, 2015 8:07 PM
> 
> After the renesas_usbhs driver is enabled in ARM multi_v7_defconfig,
> we now get a new warning:
> 
> renesas_usbhs/mod.c: In function 'usbhs_interrupt':
> renesas_usbhs/mod.c:246:7: warning: 'intenb1' may be used uninitialized in this function [-Wmaybe-uninitialized]
> 
> gcc correctly points to a problem here, for the case that the
> device is in host mode, we use the intenb1 variable without
> having assigned it first. The state->intsts1 has a similar
> problem, but gcc cannot know that.
> 
> This avoids the problem by initializing both sides of the
> comparison to zero when we don't read them from the respective
> registers.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Fixes: 88a25e02f3 ("usb: renesas_usbhs: Add access control for INTSTS1 and INTENB1 register")

Thank you very much for the patch!

Acked-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

(I'm not sure why a toolchain I used (Linaro GCC 2014.11) doesn't show this warning...)

Best regards,
Yoshihiro Shimoda

> diff --git a/drivers/usb/renesas_usbhs/mod.c b/drivers/usb/renesas_usbhs/mod.c
> index e5ce6e6d4f51..d4be5d594896 100644
> --- a/drivers/usb/renesas_usbhs/mod.c
> +++ b/drivers/usb/renesas_usbhs/mod.c
> @@ -223,6 +223,8 @@ static int usbhs_status_get_each_irq(struct usbhs_priv *priv,
>  	if (usbhs_mod_is_host(priv)) {
>  		state->intsts1 = usbhs_read(priv, INTSTS1);
>  		intenb1 = usbhs_read(priv, INTENB1);
> +	} else {
> +		state->intsts1 = intenb1 = 0;
>  	}
> 
>  	/* mask */
> 
> --
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[PATCH] usb: renesas_usbhs: avoid uninitialized variable use

[Simon Horman]

On Fri, May 22, 2015 at 11:33:57AM +0000, Yoshihiro Shimoda wrote:
> Hi Arnd,
> 
> > Sent: Friday, May 22, 2015 8:07 PM
> > 
> > After the renesas_usbhs driver is enabled in ARM multi_v7_defconfig,
> > we now get a new warning:
> > 
> > renesas_usbhs/mod.c: In function 'usbhs_interrupt':
> > renesas_usbhs/mod.c:246:7: warning: 'intenb1' may be used uninitialized in this function [-Wmaybe-uninitialized]
> > 
> > gcc correctly points to a problem here, for the case that the
> > device is in host mode, we use the intenb1 variable without
> > having assigned it first. The state->intsts1 has a similar
> > problem, but gcc cannot know that.
> > 
> > This avoids the problem by initializing both sides of the
> > comparison to zero when we don't read them from the respective
> > registers.
> > 
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > Fixes: 88a25e02f3 ("usb: renesas_usbhs: Add access control for INTSTS1 and INTENB1 register")
> 
> Thank you very much for the patch!
> 
> Acked-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> 
> (I'm not sure why a toolchain I used (Linaro GCC 2014.11) doesn't show this warning...)
> 
> Best regards,
> Yoshihiro Shimoda

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>

> 
> > diff --git a/drivers/usb/renesas_usbhs/mod.c b/drivers/usb/renesas_usbhs/mod.c
> > index e5ce6e6d4f51..d4be5d594896 100644
> > --- a/drivers/usb/renesas_usbhs/mod.c
> > +++ b/drivers/usb/renesas_usbhs/mod.c
> > @@ -223,6 +223,8 @@ static int usbhs_status_get_each_irq(struct usbhs_priv *priv,
> >  	if (usbhs_mod_is_host(priv)) {
> >  		state->intsts1 = usbhs_read(priv, INTSTS1);
> >  		intenb1 = usbhs_read(priv, INTENB1);
> > +	} else {
> > +		state->intsts1 = intenb1 = 0;
> >  	}
> > 
> >  	/* mask */
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-usb" in
> > the body of a message to majordomo at vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
>