Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37;
From:   Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
To:     stern@rowland.harvard.edu
Cc:     davem@davemloft.net, edumazet@google.com, greg@kroah.com,
        jtornosm@redhat.com, kuba@kernel.org, linux-kernel@vger.kernel.org,
        linux-usb@vger.kernel.org, netdev@vger.kernel.org,
        oneukum@suse.com, pabeni@redhat.com, stable@vger.kernel.org
Subject: Re: [PATCH v4] net: usb: ax88179_178a: avoid failed operations when device is disconnected
Date:   Wed,  6 Dec 2023 13:17:32 +0100
Message-ID: <20231206121732.7154-1-jtornosm@redhat.com>
In-Reply-To: <624ad05b-0b90-4d1c-b06b-7a75473401c3@rowland.harvard.edu>
References: <624ad05b-0b90-4d1c-b06b-7a75473401c3@rowland.harvard.edu>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

Hello Alan,

> The __ax88179_read_cmd() and __ax88179_write_cmd() routines are 
> asynchronous with respect to ax88179_disconnect(), right?  Or at least, 
> they are if they run as a result of the user closing the network 
> interface.  Otherwise there wouldn't be any memory ordering issues.
Yes, I think so, they could be asynchronous regarding ax88179_disconnect.

> But the memory barriers you added are not the proper solution.  What you 
> need here is _synchronization_, not _ordering_.  As it is, the memory 
> barriers you have added don't do anything; they shouldn't be in the 
> patch.
Ok, thank you for the helpful clarification, let me check it better,
I understood it in a wrong way.

> If you would like a more in-depth explanation, let me know.
Thank you for your help, I will try first, I really appreciate this.

Best regards
José Ignacio