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From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Paolo Bonzini <pbonzini@redhat.com>
CC:     Alex Williamson <alex.williamson@redhat.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        "Christopherson,, Sean" <seanjc@google.com>,
        "Bradescu, Roxana" <roxabee@google.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v3 2/2] kvm/vfio: avoid bouncing the mutex when adding and
 deleting groups
Thread-Topic: [PATCH v3 2/2] kvm/vfio: avoid bouncing the mutex when adding
 and deleting groups
Thread-Index: AQHZtqT6WmtjXEfJ/0GeKcImZTi8I6/AlmDw
Date:   Wed, 19 Jul 2023 05:32:27 +0000
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References: <20230714224538.404793-1-dmitry.torokhov@gmail.com>
 <20230714224538.404793-2-dmitry.torokhov@gmail.com>
In-Reply-To: <20230714224538.404793-2-dmitry.torokhov@gmail.com>
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> From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Sent: Saturday, July 15, 2023 6:46 AM
>
> @@ -165,30 +161,26 @@ static int kvm_vfio_group_add(struct kvm_device
> *dev, unsigned int fd)
>  	list_for_each_entry(kvg, &kv->group_list, node) {
>  		if (kvg->file =3D=3D filp) {
>  			ret =3D -EEXIST;
> -			goto err_unlock;
> +			goto out_unlock;
>  		}
>  	}
>=20
>  	kvg =3D kzalloc(sizeof(*kvg), GFP_KERNEL_ACCOUNT);
>  	if (!kvg) {
>  		ret =3D -ENOMEM;
> -		goto err_unlock;
> +		goto out_unlock;
>  	}
>=20
> -	kvg->file =3D filp;
> +	kvg->file =3D get_file(filp);

Why is another reference required here?