On 04.11.25 00:28, Michael S. Tsirkin wrote:
> On Wed, Oct 15, 2025 at 05:58:06PM +0300, Vladimir Sementsov-Ogievskiy wrote:
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
>> Reviewed-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
>> Reviewed-by: Raphael Norwitz <raphael.s.norwitz@gmail.com>
>> ---
>> hw/block/trace-events | 10 ++++++++++
>> hw/block/vhost-user-blk.c | 19 +++++++++++++++++++
>> 2 files changed, 29 insertions(+)
>>
>> diff --git a/hw/block/trace-events b/hw/block/trace-events
>> index cc9a9f2460..dbaa5ca6cb 100644
>> --- a/hw/block/trace-events
>> +++ b/hw/block/trace-events
>> @@ -58,6 +58,16 @@ virtio_blk_handle_zone_mgmt(void *vdev, void *req, uint8_t op, int64_t sector, i
>> virtio_blk_handle_zone_reset_all(void *vdev, void *req, int64_t sector, int64_t len) "vdev %p req %p sector 0x%" PRIx64 " cap 0x%" PRIx64 ""
>> virtio_blk_handle_zone_append(void *vdev, void *req, int64_t sector) "vdev %p req %p, append sector 0x%" PRIx64 ""
>>
>> +# vhost-user-blk.c
>> +vhost_user_blk_start_in(void *vdev) "vdev %p"
>> +vhost_user_blk_start_out(void *vdev) "vdev %p"
>> +vhost_user_blk_stop_in(void *vdev) "vdev %p"
>> +vhost_user_blk_stop_out(void *vdev) "vdev %p"
>> +vhost_user_blk_connect_in(void *vdev) "vdev %p"
>> +vhost_user_blk_connect_out(void *vdev) "vdev %p"
>> +vhost_user_blk_device_realize_in(void *vdev) "vdev %p"
>> +vhost_user_blk_device_realize_out(void *vdev) "vdev %p"
>> +
>> # hd-geometry.c
>> hd_geometry_lchs_guess(void *blk, int cyls, int heads, int secs) "blk %p LCHS %d %d %d"
>> hd_geometry_guess(void *blk, uint32_t cyls, uint32_t heads, uint32_t secs, int trans) "blk %p CHS %u %u %u trans %d"
>> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
>> index de7a810c93..a5daed4346 100644
>> --- a/hw/block/vhost-user-blk.c
>> +++ b/hw/block/vhost-user-blk.c
>> @@ -31,6 +31,7 @@
>> #include "hw/virtio/virtio-access.h"
>> #include "system/system.h"
>> #include "system/runstate.h"
>> +#include "trace.h"
>>
>> static const int user_feature_bits[] = {
>> VIRTIO_BLK_F_SIZE_MAX,
>> @@ -137,6 +138,8 @@ static int vhost_user_blk_start(VirtIODevice *vdev, Error **errp)
>> VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
>> int i, ret;
>>
>> + trace_vhost_user_blk_start_in(vdev);
>> +
>> if (!k->set_guest_notifiers) {
>> error_setg(errp, "binding does not support guest notifiers");
>> return -ENOSYS;
>> @@ -192,6 +195,8 @@ static int vhost_user_blk_start(VirtIODevice *vdev, Error **errp)
>> }
>> s->started_vu = true;
>>
>> + trace_vhost_user_blk_start_out(vdev);
>> +
>> return ret;
>>
>> err_guest_notifiers:
>> @@ -212,6 +217,8 @@ static int vhost_user_blk_stop(VirtIODevice *vdev)
>> int ret;
>> bool force_stop = false;
>>
>> + trace_vhost_user_blk_stop_in(vdev);
>> +
>> if (!s->started_vu) {
>> return 0;
>> }
>> @@ -233,6 +240,9 @@ static int vhost_user_blk_stop(VirtIODevice *vdev)
>> }
>>
>> vhost_dev_disable_notifiers(&s->dev, vdev);
>> +
>> + trace_vhost_user_blk_stop_out(vdev);
>> +
>> return ret;
>> }
>>
>> @@ -340,6 +350,8 @@ static int vhost_user_blk_connect(DeviceState *dev, Error **errp)
>> VHostUserBlk *s = VHOST_USER_BLK(vdev);
>> int ret = 0;
>>
>> + trace_vhost_user_blk_connect_in(vdev);
>> +
>> if (s->connected) {
>> return 0;
>> }
>> @@ -365,6 +377,8 @@ static int vhost_user_blk_connect(DeviceState *dev, Error **errp)
>> ret = vhost_user_blk_start(vdev, errp);
>> }
>>
>> + trace_vhost_user_blk_connect_out(vdev);
>> +
>> return ret;
>> }
>>
>> @@ -455,6 +469,8 @@ static void vhost_user_blk_device_realize(DeviceState *dev, Error **errp)
>> int retries;
>> int i, ret;
>>
>> + trace_vhost_user_blk_device_realize_in(vdev);
>> +
>> if (!s->chardev.chr) {
>> error_setg(errp, "chardev is mandatory");
>> return;
>> @@ -514,6 +530,9 @@ static void vhost_user_blk_device_realize(DeviceState *dev, Error **errp)
>> qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL,
>> vhost_user_blk_event, NULL, (void *)dev,
>> NULL, true);
>> +
>> + trace_vhost_user_blk_device_realize_out(vdev);
>> +
>> return;
>>
>> virtio_err:
>
>
> Is it ok that on error there's an in trace but not an out trace?
>
I thought about it.
In my opinion, switching to use common "out: " and gotos instead of simple returns,
is too much pay for proper out trace-points.
So, it's a compromise: we have at least trace-point on success-out, and don't make
the code more complicated just for good trace points.
Probably, we can invent some smart macro, which will inject out tracepoint using
g_auto...
--
Best regards,
Vladimir