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Date: Sun, 27 Aug 2023 18:51:30 +0200
From: Simon Horman <horms@kernel.org>
To: Mikhail Kobuk <m.kobuk@ispras.ru>
Cc: Siva Reddy Kallam <siva.kallam@broadcom.com>,
	Prashant Sreedharan <prashant@broadcom.com>,
	Michael Chan <mchan@broadcom.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Richard Cochran <richardcochran@gmail.com>,
	Jean Delvare <jdelvare@suse.com>,
	Guenter Roeck <linux@roeck-us.net>, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org,
	lvc-project@linuxtesting.org,
	Alexey Khoroshilov <khoroshilov@ispras.ru>,
	Matt Carlson <mcarlson@broadcom.com>
Subject: Re: [PATCH] ethernet: tg3: remove unreachable code
Message-ID: <20230827165130.GV3523530@kernel.org>
References: <20230825190443.48375-1-m.kobuk@ispras.ru>
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In-Reply-To: <20230825190443.48375-1-m.kobuk@ispras.ru>

On Fri, Aug 25, 2023 at 10:04:41PM +0300, Mikhail Kobuk wrote:

+ Matt Carlson <mcarlson@broadcom.com>

> 'tp->irq_max' value is either 1 [L16336] or 5 [L16354], as indicated in
> tg3_get_invariants(). Therefore, 'i' can't exceed 4 in tg3_init_one()
> that makes (i <= 4) always true. Moreover, 'intmbx' value set at the
> last iteration is not used later in it's scope.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 78f90dcf184b ("tg3: Move napi_add calls below tg3_get_invariants")
> Signed-off-by: Mikhail Kobuk <m.kobuk@ispras.ru>
> Reviewed-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
> ---
>  drivers/net/ethernet/broadcom/tg3.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
> index 5ef073a79ce9..6b6da2484dfe 100644
> --- a/drivers/net/ethernet/broadcom/tg3.c
> +++ b/drivers/net/ethernet/broadcom/tg3.c
> @@ -17792,10 +17792,7 @@ static int tg3_init_one(struct pci_dev *pdev,
>  		tnapi->tx_pending = TG3_DEF_TX_RING_PENDING;
>  
>  		tnapi->int_mbox = intmbx;
> -		if (i <= 4)
> -			intmbx += 0x8;
> -		else
> -			intmbx += 0x4;
> +		intmbx += 0x8;
>  
>  		tnapi->consmbox = rcvmbx;
>  		tnapi->prodmbox = sndmbx;
> -- 
> 2.42.0
> 
>