linux-kernel - Re: [PATCH 5.10 048/126] net: ethernet: aquantia: Handle error cleanup of start on open

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Message-ID: <20210405153743.GA305@amd>
Date:   Mon, 5 Apr 2021 17:37:43 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Nathan Rossi <nathan.rossi@...i.com>,
        Igor Russkikh <irusskikh@...vell.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.10 048/126] net: ethernet: aquantia: Handle error
 cleanup of start on open

Hi!

> From: Nathan Rossi <nathan.rossi@...i.com>
> 
> [ Upstream commit 8a28af7a3e85ddf358f8c41e401a33002f7a9587 ]
> 
> The aq_nic_start function can fail in a variety of cases which leaves
> the device in broken state.
> 
> An example case where the start function fails is the
> request_threaded_irq which can be interrupted, resulting in a EINTR
> result. This can be manually triggered by bringing the link up (e.g. ip
> link set up) and triggering a SIGINT on the initiating process (e.g.
> Ctrl+C). This would put the device into a half configured state.
> Subsequently bringing the link up again would cause the napi_enable to
> BUG.
> 
> In order to correctly clean up the failed attempt to start a device call
> aq_nic_stop.

No.

> +++ b/drivers/net/ethernet/aquantia/atlantic/aq_main.c
> @@ -71,8 +71,10 @@ static int aq_ndev_open(struct net_device *ndev)
>  		goto err_exit;
>  
>  	err = aq_nic_start(aq_nic);
> -	if (err < 0)
> +	if (err < 0) {
> +		aq_nic_stop(aq_nic);
>  		goto err_exit;
> +	}
>  
>  err_exit:
>  	if (err < 0)

First, take a look at the goto. Does not need to be there.

Second check the crazy calling convention. If nic_start() fails, it
should clean up after itself.

Then, check the code. nic_stop() undoes initialization that was not
even done in the nic_start().

This introduces more problems than it solves.

Best regards,
							Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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