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Date:   Mon, 28 Sep 2020 07:23:05 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Shuo A Liu <shuo.a.liu@intel.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Yu Wang <yu1.wang@intel.com>,
        Reinette Chatre <reinette.chatre@intel.com>,
        Zhi Wang <zhi.a.wang@intel.com>,
        Zhenyu Wang <zhenyuw@linux.intel.com>
Subject: Re: [PATCH v4 17/17] virt: acrn: Introduce an interface for Service
 VM to control vCPU
Message-ID: <20200928052305.GC767987@kroah.com>
References: <20200922114311.38804-1-shuo.a.liu@intel.com>
 <20200922114311.38804-18-shuo.a.liu@intel.com>
 <20200927104414.GC88650@kroah.com>
 <20200928041006.GE1057@shuo-intel.sh.intel.com>
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On Mon, Sep 28, 2020 at 12:10:07PM +0800, Shuo A Liu wrote:
> > You just raced with userspace and lost.  If you want to add attribute
> > files to a device, use the default attribute group list, and it will be
> > managed properly for you by the driver core.
> > 
> > Huge hint, if a driver every has to touch a kobject, or call sysfs_*,
> > then it is probably doing something wrong.
> 
> Do you mean use .groups of struct miscdevice directly ?
> 
> If yes, let me follow drivers/char/hw_random/s390-trng.c to do this.
> BTW, few driver use the .groups directly. :)

Drivers should almost never be messing with individual sysfs files.  And
this ability to use .groups is a "new" one, conversions of existing code
that do not use them is always welcome.

thanks,

greg k-h