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Tsirkin" To: Xie Yongji Cc: jasowang@redhat.com, stefanha@redhat.com, sgarzare@redhat.com, parav@nvidia.com, hch@infradead.org, christian.brauner@canonical.com, rdunlap@infradead.org, willy@infradead.org, viro@zeniv.linux.org.uk, axboe@kernel.dk, bcrl@kvack.org, corbet@lwn.net, mika.penttila@nextfour.com, dan.carpenter@oracle.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v6 03/10] vhost-vdpa: protect concurrent access to vhost device iotlb Message-ID: <20210409121512-mutt-send-email-mst@kernel.org> References: <20210331080519.172-1-xieyongji@bytedance.com> <20210331080519.172-4-xieyongji@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210331080519.172-4-xieyongji@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Mar 31, 2021 at 04:05:12PM +0800, Xie Yongji wrote: > Use vhost_dev->mutex to protect vhost device iotlb from > concurrent access. > > Fixes: 4c8cf318("vhost: introduce vDPA-based backend") > Cc: stable@vger.kernel.org > Signed-off-by: Xie Yongji > Acked-by: Jason Wang > Reviewed-by: Stefano Garzarella I could not figure out whether there's a bug there now. If yes when is the concurrent access triggered? > --- > drivers/vhost/vdpa.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index 3947fbc2d1d5..63b28d3aee7c 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -725,9 +725,11 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, > const struct vdpa_config_ops *ops = vdpa->config; > int r = 0; > > + mutex_lock(&dev->mutex); > + > r = vhost_dev_check_owner(dev); > if (r) > - return r; > + goto unlock; > > switch (msg->type) { > case VHOST_IOTLB_UPDATE: > @@ -748,6 +750,8 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, > r = -EINVAL; > break; > } > +unlock: > + mutex_unlock(&dev->mutex); > > return r; > } > -- > 2.11.0