[lttng-dev] lttng-modules: block: invalid/unknown value for rwbs field

[Awais Belal]

Hi,

I am using lttng-modules 2.12.5 with a 5.4.93 kernel on an aarch64 
target. After creating a session I run

*lttng enable-event -k block**

to enable all the block_ kernel events but when I run babeltrace on the 
generated traces I get a handful of

*[warning] Unknown value 33 in enum.
...
...
*

with different values in place of 33. This does not happen with any 
other kernel event type

*BabelTrace Trace Viewer and Converter 1.5.8*

Also if I try to do a 'lttng view' on this session I can identify that 
this has something to do with the rwbs field as I get

*[14:03:42.649719750] (+0.000005750) imx8qxpmek block_bio_remap: { 
cpu_id = 3 }, { dev = 187695200, sector = 2460080, nr_sector = 8, rwbs = 
( <unknown> : container = 33 ), old_dev = 187695203, old_sector = 2105776 }
[14:03:42.649722125] (+0.000002375) imx8qxpmek block_bio_queue: { cpu_id 
= 3 }, { dev = 187695200, sector = 2460080, nr_sector = 8, rwbs = ( 
<unknown> : container = 33 ), tid = 428, comm = "jbd2/mmcblk1p3-" }
[14:03:42.649725000] (+0.000002875) imx8qxpmek block_bio_backmerge: { 
cpu_id = 3 }, { dev = 187695200, sector = 2460080, nr_sector = 8, rwbs = 
( <unknown> : container = 33 ), tid = 428, comm = "jbd2/mmcblk1p3-" }
...
...*

I believe <unknown> in the log points to a symptom? While for the 
events/container id that do not generate this warning I have in the same 
trace

*[14:03:44.697572375] (+2.036943500) imx8qxpmek block_bio_remap: { 
cpu_id = 0 }, { dev = 187695200, sector = 9382032, nr_sector = 8, rwbs = 
( "RWBS_FLAG_WRITE" : container = 1 ), old_dev = 187695206, old_sector = 
278672 }
[14:03:44.697584375] (+0.000012000) imx8qxpmek block_bio_queue: { cpu_id 
= 0 }, { dev = 187695200, sector = 9382032, nr_sector = 8, rwbs = ( 
"RWBS_FLAG_WRITE" : container = 1 ), tid = 1609, comm = "kworker/u8:0" }
[14:03:44.697604250] (+0.000019875) imx8qxpmek block_getrq: { cpu_id = 0 
}, { dev = 187695200, sector = 9382032, nr_sector = 8, rwbs = ( 
"RWBS_FLAG_WRITE" : container = 1 ), tid = 1609, comm = "kworker/u8:0" }*

The interesting thing to note with the working events is that all of 
them have "RWBS_FLAG_WRITE" and no other types from 
https://github.com/lttng/lttng-modules/blob/stable-2.12/instrumentation/events/lttng-module/block.h#L39 
which I would expect to see.

I am lost for hints as to what I need to look up... any help would be 
highly appreciated.

-- 
BR,
Awais

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