[v3] virtio: features,fixes

[PULL v3 50/85] vhost-user-server: do not set memory fd non-blocking

Michael S. Tsirkin posted 85 patches 2 months, 2 weeks ago

Diff against v1 v1 v2 v2 v3
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Maintainers: David Hildenbrand <david@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Raphael Norwitz <raphael@enfabrica.net>, "Michael S. Tsirkin" <mst@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Shannon Zhao <shannon.zhaosl@gmail.com>, Ani Sinha <anisinha@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, Eduardo Habkost <eduardo@habkost.net>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Yanan Wang <wangyanan55@huawei.com>, Jonathan Cameron <jonathan.cameron@huawei.com>, Fan Ni <fan.ni@samsung.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Sergio Lopez <slp@redhat.com>, Akihiko Odaki <akihiko.odaki@daynix.com>, Sriram Yagnaraman <sriram.yagnaraman@ericsson.com>, Jason Wang <jasowang@redhat.com>, Keith Busch <kbusch@kernel.org>, Klaus Jensen <its@irrelevant.dk>, Jesper Devantier <foss@defmacro.it>, Nicholas Piggin <npiggin@gmail.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, David Gibson <david@gibson.dropbear.id.au>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Thomas Huth <thuth@redhat.com>, Fam Zheng <fam@euphon.net>, "Alex Bennée" <alex.bennee@linaro.org>, Stefan Hajnoczi <stefanha@redhat.com>, Eric Auger <eric.auger@redhat.com>, Stefano Stabellini <sstabellini@kernel.org>, Anthony PERARD <anthony@xenproject.org>, Paul Durrant <paul@xen.org>, Cornelia Huck <cohuck@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>, David Woodhouse <dwmw2@infradead.org>, Laurent Vivier <lvivier@redhat.com>, Coiby Xu <Coiby.Xu@gmail.com>

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[PULL v3 50/85] vhost-user-server: do not set memory fd non-blocking

Posted by Michael S. Tsirkin 2 months, 2 weeks ago

From: Stefano Garzarella <sgarzare@redhat.com>

In vhost-user-server we set all fd received from the other peer
in non-blocking mode. For some of them (e.g. memfd, shm_open, etc.)
it's not really needed, because we don't use these fd with blocking
operations, but only to map memory.

In addition, in some systems this operation can fail (e.g. in macOS
setting an fd returned by shm_open() non-blocking fails with errno
= ENOTTY).

So, let's avoid setting fd non-blocking for those messages that we
know carry memory fd (e.g. VHOST_USER_ADD_MEM_REG,
VHOST_USER_SET_MEM_TABLE).

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20240618100043.144657-6-sgarzare@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 util/vhost-user-server.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
index 3bfb1ad3ec..b19229074a 100644
--- a/util/vhost-user-server.c
+++ b/util/vhost-user-server.c
@@ -65,6 +65,18 @@ static void vmsg_close_fds(VhostUserMsg *vmsg)
 static void vmsg_unblock_fds(VhostUserMsg *vmsg)
 {
     int i;
+
+    /*
+     * These messages carry fd used to map memory, not to send/receive messages,
+     * so this operation is useless. In addition, in some systems this
+     * operation can fail (e.g. in macOS setting an fd returned by shm_open()
+     * non-blocking fails with errno = ENOTTY)
+     */
+    if (vmsg->request == VHOST_USER_ADD_MEM_REG ||
+        vmsg->request == VHOST_USER_SET_MEM_TABLE) {
+        return;
+    }
+
     for (i = 0; i < vmsg->fd_num; i++) {
         qemu_socket_set_nonblock(vmsg->fds[i]);
     }
-- 
MST