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Date:   Tue, 20 Jun 2023 09:06:57 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Saurabh Singh Sengar <ssengar@microsoft.com>
Cc:     Saurabh Sengar <ssengar@linux.microsoft.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "wei.liu@kernel.org" <wei.liu@kernel.org>,
        Dexuan Cui <decui@microsoft.com>,
        "Michael Kelley (LINUX)" <mikelley@microsoft.com>,
        "corbet@lwn.net" <corbet@lwn.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>
Subject: Re: [EXTERNAL] Re: [PATCH v2 1/5] uio: Add hv_vmbus_client driver
Message-ID: <2023062007-coral-nicotine-856c@gregkh>
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On Tue, Jun 20, 2023 at 05:19:14AM +0000, Saurabh Singh Sengar wrote:
> > And you are defining a "global" variable that can be modified by an individual
> > sysfs file for ANY device bound to this driver, messing with the other device's
> > ring buffer size, right?  This needs to be per-device, or explain in huge detail
> > here why not.
> 
> The global variable is expected to be set by userspace per device before opening, the
> particular uio device. For a particular Hyper-v device this value be same, and once
> device is open the ring buffer is allocated and there won't be any impact afterwards
> changing it. I can elaborate more of this in sysfs documentation.

That's totally confusing, please make this per-device properly, as you
will find out when you try to document it, what you are describing is
unlike any other per-device interface we have.

greg k-h