[libvirt] [QEMU PATCH] net: Deprecate the old way of using a legacy net via "name" instead of "id"

[Thomas Huth]

In early times, network backends were specified by a "vlan" and "name"
tuple. With the introduction of netdevs, the "name" was replaced by an
"id" (which is supposed to be unique), but the "name" parameter stayed
as an alias which could be used instead of "id". Unfortunately, we miss
the duplication check for "name":

 $ qemu-system-x86_64 -net user,name=n1 -net user,name=n1

... starts without an error, while "id" correctly complains:

 $ qemu-system-x86_64 -net user,id=n1 -net user,id=n1
 qemu-system-x86_64: -net user,id=n1: Duplicate ID 'n1' for net

Instead of trying to fix the code for the legacy "name" parameter, let's
rather get rid of this old interface and deprecate the "name" parameter
now - this will also be less confusing for the users in the long run.

While we're at it, also deprecate the old syntax for the hostfwd_add
and hostfwd_remove commands that still work with this legacy "hub"
plus "name" tuple. It is enough to specify the netdev id there instead.

Also add a missing dependency to the Makefile to make sure that the
docs get correctly regenerated when qemu-deprecated.texi is changed.

Signed-off-by: Thomas Huth <thuth at redhat.com>
---
 Makefile             |  2 +-
 net/net.c            |  4 ++++
 net/slirp.c          |  2 ++
 qemu-deprecated.texi | 13 +++++++++++++
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index fe623e4..f42e176 100644
--- a/Makefile
+++ b/Makefile
@@ -978,7 +978,7 @@ txt: qemu-doc.txt docs/interop/qemu-qmp-ref.txt docs/interop/qemu-ga-ref.txt
 
 qemu-doc.html qemu-doc.info qemu-doc.pdf qemu-doc.txt: \
 	qemu-img.texi qemu-nbd.texi qemu-options.texi qemu-option-trace.texi \
-	qemu-monitor.texi qemu-img-cmds.texi qemu-ga.texi \
+	qemu-deprecated.texi qemu-monitor.texi qemu-img-cmds.texi qemu-ga.texi \
 	qemu-monitor-info.texi docs/qemu-block-drivers.texi \
 	docs/qemu-cpu-models.texi
 
diff --git a/net/net.c b/net/net.c
index 2a31339..cdcd5cf 100644
--- a/net/net.c
+++ b/net/net.c
@@ -984,6 +984,10 @@ static int net_client_init1(const void *object, bool is_netdev, Error **errp)
         /* missing optional values have been initialized to "all bits zero" */
         name = net->has_id ? net->id : net->name;
 
+        if (net->has_name) {
+            warn_report("The 'name' parameter is deprecated, use 'id' instead");
+        }
+
         /* Map the old options to the new flat type */
         switch (opts->type) {
         case NET_LEGACY_OPTIONS_TYPE_NONE:
diff --git a/net/slirp.c b/net/slirp.c
index c18060f..073bc69 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -404,6 +404,8 @@ static SlirpState *slirp_lookup(Monitor *mon, const char *hub_id,
                 monitor_printf(mon, "unrecognized (hub-id, stackname) pair\n");
                 return NULL;
             }
+            warn_report("Using 'hub-id' is deprecated. Specify the netdev id "
+                        "directly instead");
         } else {
             nc = qemu_find_netdev(name);
             if (!nc) {
diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
index 8a2e399..eed7132 100644
--- a/qemu-deprecated.texi
+++ b/qemu-deprecated.texi
@@ -83,6 +83,11 @@ The 'file' driver for drives is no longer appropriate for character or host
 devices and will only accept regular files (S_IFREG). The correct driver
 for these file types is 'host_cdrom' or 'host_device' as appropriate.
 
+ at subsection -net ...,name=@var{name} (since 3.1)
+
+The @option{name} parameter of the @option{-net} option is an old synonym
+for the @option{id} parameter which should now be used instead.
+
 @section QEMU Machine Protocol (QMP) commands
 
 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
@@ -99,6 +104,14 @@ The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
 The ``arch'' output member of the ``query-cpus-fast'' command is
 replaced by the ``target'' output member.
 
+ at section System emulator human monitor commands
+
+ at subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
+
+The @option{hub_id} parameter of the 'hostfwd_add' and 'hostfwd_remove' HMP
+commands is redundant. It is enough to specify the netdev ID of the backend
+that should be changed.
+
 @section System emulator devices
 
 @subsection ivshmem (since 2.6.0)
-- 
1.8.3.1