Re: [PULL 37/40] monitor: Tidy up find_device_state()

[Christian Borntraeger]

Am 13.10.21 um 11:07 schrieb Paolo Bonzini:
> From: Markus Armbruster <armbru@redhat.com>
>
> Commit 6287d827d4 "monitor: allow device_del to accept QOM paths"
> extended find_device_state() to accept QOM paths in addition to qdev
> IDs.  This added a checked conversion to TYPE_DEVICE at the end, which
> duplicates the check done for the qdev ID case earlier, except it sets
> a *different* error: GenericError "ID is not a hotpluggable device"
> when passed a QOM path, and DeviceNotFound "Device 'ID' not found"
> when passed a qdev ID.  Fortunately, the latter won't happen as long
> as we add only devices to /machine/peripheral/.
>
> Earlier, commit b6cc36abb2 "qdev: device_del: Search for to be
> unplugged device in 'peripheral' container" rewrote the lookup by qdev
> ID to use QOM instead of qdev_find_recursive(), so it can handle
> buss-less devices.  It does so by constructing an absolute QOM path.
> Works, but object_resolve_path_component() is easier.  Switching to it
> also gets rid of the unclean duplication described above.
>
> While there, avoid converting to TYPE_DEVICE twice, first to check
> whether it's possible, and then for real.

This one broke qemu iotest 280 on s390:


280   fail       [13:06:19] [13:06:19]   0.3s   (last: 0.3s)  output mismatch 
(see 280.out.bad)
--- /home/cborntra/REPOS/qemu/tests/qemu-iotests/280.out
+++ 280.out.bad
@@ -37,14 +37,14 @@
 === Resume the VM and simulate a write request ===
 {"execute": "cont", "arguments": {}}
 {"return": {}}
-{"return": ""}
+{"return": "Error: Device 'vda/virtio-backend' not found\r\n"}

 === Commit it to the backing file ===
 {"execute": "block-commit", "arguments": {"auto-dismiss": false, "device": "top-fmt", "job-id": 
"job0", "top-node": "top-fmt"}}
 {"return": {}}
 {"execute": "job-complete", "arguments": {"id": "job0"}}
 {"return": {}}
-{"data": {"device": "job0", "len": 65536, "offset": 65536, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_READY", 
"timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
-{"data": {"device": "job0", "len": 65536, "offset": 65536, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_COMPLETED", 
"timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"data": {"device": "job0", "len": 0, "offset": 0, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_READY", 
"timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"data": {"device": "job0", "len": 0, "offset": 0, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_COMPLETED", 
"timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
 {"execute": "job-dismiss", "arguments": {"id": "job0"}}
 {"return": {}}
Failures: 280
Failed 1 of 1 iotests


> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
> Message-Id: <20210916111707.84999-1-armbru@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   softmmu/qdev-monitor.c | 13 +++++--------
>   1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
> index 0705f00846..3df99ce9fc 100644
> --- a/softmmu/qdev-monitor.c
> +++ b/softmmu/qdev-monitor.c
> @@ -836,16 +836,12 @@ void qmp_device_add(QDict *qdict, QObject **ret_data, 
> Error **errp)
>   static DeviceState *find_device_state(const char *id, Error **errp)
>   {
>       Object *obj;
> +    DeviceState *dev;
>   
>       if (id[0] == '/') {
>           obj = object_resolve_path(id, NULL);
>       } else {
> -        char *root_path = object_get_canonical_path(qdev_get_peripheral());
> -        char *path = g_strdup_printf("%s/%s", root_path, id);
> -
> -        g_free(root_path);
> -        obj = object_resolve_path_type(path, TYPE_DEVICE, NULL);
> -        g_free(path);
> +        obj = object_resolve_path_component(qdev_get_peripheral(), id);
>       }
>   
>       if (!obj) {
> @@ -854,12 +850,13 @@ static DeviceState *find_device_state(const char *id, 
> Error **errp)
>           return NULL;
>       }
>   
> -    if (!object_dynamic_cast(obj, TYPE_DEVICE)) {
> +    dev = (DeviceState *)object_dynamic_cast(obj, TYPE_DEVICE);
> +    if (!dev) {
>           error_setg(errp, "%s is not a hotpluggable device", id);
>           return NULL;
>       }
>   
> -    return DEVICE(obj);
> +    return dev;
>   }
>   
>   void qdev_unplug(DeviceState *dev, Error **errp)