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Message-ID: <62fec09e-c881-498e-9ac0-d0a6de665f16@rowland.harvard.edu>
Date: Wed, 27 Sep 2023 09:43:37 -0400
From: Alan Stern <stern@...land.harvard.edu>
To: Douglas Anderson <dianders@...omium.org>
Cc: Jakub Kicinski <kuba@...nel.org>,
Hayes Wang <hayeswang@...ltek.com>,
"David S . Miller" <davem@...emloft.net>,
linux-usb@...r.kernel.org, Grant Grundler <grundler@...omium.org>,
Edward Hill <ecgh@...omium.org>, andre.przywara@....com,
bjorn@...k.no, edumazet@...gle.com, gaul@...l.org,
horms@...nel.org, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, pabeni@...hat.com
Subject: Re: [PATCH 2/3] r8152: Retry register reads/writes
On Tue, Sep 26, 2023 at 02:27:27PM -0700, Douglas Anderson wrote:
> +
> +static
> +int r8152_control_msg(struct usb_device *udev, unsigned int pipe, __u8 request,
> + __u8 requesttype, __u16 value, __u16 index, void *data,
> + __u16 size, const char *msg_tag)
> +{
> + int i;
> + int ret;
> +
> + for (i = 0; i < REGISTER_ACCESS_TRIES; i++) {
> + ret = usb_control_msg(udev, pipe, request, requesttype,
> + value, index, data, size,
> + USB_CTRL_GET_TIMEOUT);
> +
> + /* No need to retry or spam errors if the USB device got
> + * unplugged; just return immediately.
> + */
> + if (udev->state == USB_STATE_NOTATTACHED)
> + return ret;
Rather than testing udev->state, it would be better to check whether
ret == -ENODEV. udev->state is meant primarily for use by the USB core
and it's subject to races.
Alan Stern
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