Re: [Qemu-block] [PATCH v3 1/2] qapi: move to QOM path for x-block-latency-histogram-set

[Vladimir Sementsov-Ogievskiy]

11.02.2019 20:54, Kevin Wolf wrote:
> Am 21.12.2018 um 17:53 hat Vladimir Sementsov-Ogievskiy geschrieben:
>> Move to way of device selecting, however fall back to device name if
>> path is not found.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>> ---
>>   qapi/block-core.json |  4 ++--
>>   blockdev.c           | 22 +++++++++++++++-------
>>   2 files changed, 17 insertions(+), 9 deletions(-)
>>
>> diff --git a/qapi/block-core.json b/qapi/block-core.json
>> index 762000f31f..bb70c51a57 100644
>> --- a/qapi/block-core.json
>> +++ b/qapi/block-core.json
>> @@ -489,7 +489,7 @@
>>   # If only @device parameter is specified, remove all present latency 
>> histograms
>>   # for the device. Otherwise, add/reset some of (or all) latency histograms.
>>   #
>> -# @device: device name to set latency histogram for.
>> +# @id: The QOM path or name of the guest device.
>>   #
>>   # @boundaries: list of interval boundary values (see description in
>>   #              BlockLatencyHistogramInfo definition). If specified, all
>> @@ -547,7 +547,7 @@
>>   # <- { "return": {} }
>>   ##
>>   { 'command': 'x-block-latency-histogram-set',
>> -  'data': {'device': 'str',
>> +  'data': {'id': 'str',
>>              '*boundaries': ['uint64'],
>>              '*boundaries-read': ['uint64'],
>>              '*boundaries-write': ['uint64'],
>> diff --git a/blockdev.c b/blockdev.c
>> index a6f71f9d83..ff0d8ded5e 100644
>> --- a/blockdev.c
>> +++ b/blockdev.c
>> @@ -4397,21 +4397,29 @@ void qmp_x_blockdev_set_iothread(const char 
>> *node_name, StrOrNull *iothread,
>>   }
>>   
>>   void qmp_x_block_latency_histogram_set(
>> -    const char *device,
>> +    const char *id,
>>       bool has_boundaries, uint64List *boundaries,
>>       bool has_boundaries_read, uint64List *boundaries_read,
>>       bool has_boundaries_write, uint64List *boundaries_write,
>>       bool has_boundaries_flush, uint64List *boundaries_flush,
>>       Error **errp)
>>   {
>> -    BlockBackend *blk = blk_by_name(device);
>>       BlockAcctStats *stats;
>>       int ret;
>> +    Error *local_err = NULL;
>> +    BlockBackend *blk = blk_by_qdev_id(id, &local_err);
>>   
>>       if (!blk) {
>> -        error_setg(errp, "Device '%s' not found", device);
>> -        return;
>> +        blk = blk_by_name(id);
>> +        if (!blk) {
>> +            error_propagate(errp, local_err);
>> +            return;
>> +        } else {
>> +            error_free(local_err);
>> +            local_err = NULL;
>> +        }
>>       }
> 
> Why don't you use qmp_get_blk() here?
> 

qmp_get_blk is used for cases when we have both @device and @id parameters, 
where @device is deprecated.

And one of previous iteration was a try to do it in this way (have both @id and 
@device). But it was
considered to be bad idea for a new command, which don't need any backward 
compatibility. And we decided
to merge two variants in @id.

So, do you suggest to drop blk_by_name() variant at all, and go through 
qmp_get_blk(NULL, id), which
will call blk_by_qdev_id() and fail if not found?


-- 
Best regards,
Vladimir