Bug #343: When enable-event with invalid filter, error is given but the event is still enabled - LTTng-tools - LTTng bugs repository

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Bug #343

closed

When enable-event with invalid filter, error is given but the event is still enabled

Added by Tan le tran over 11 years ago. Updated over 11 years ago.

Status:

Resolved

Priority:

High

Assignee:

David Goulet

Target version:

LTTng - 2.1 stable

Start date:

09/18/2012

Due date:

% Done:

100%

Estimated time:

Description

Scenario: =========

1)_ lttng create ses1 -o /cluster/temp/sessiondir/ses1
2)_ lttng enable-event ust_tests_demo2:loop -u --filter ' intfield => 2 '
get:
error syntax error
Parse error
Error: Error setting filter
3)_ lttng list ses1
get:
:
Events:
ust_tests_demo2:loop (type: tracepoint) [enabled]

Expected Behaviour: ===================
The event should not be enabled if the specified filter is invalid.

Files

log.txt (13.5 KB) log.txt

Terminal log with "sessiond -vvv"

Tan le tran, 09/18/2012 05:08 PM

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Updated by Tan le tran over 11 years ago

The above issue has been observed with the following commits:

userspace : (Thu Sep 6 ) a5a9f42 Ensure that read-side functions meet 10-line LGPL criterion
lttng-ust : (Tue Sep 18) 5d3bc5e Fix: get_wait_shm() ust mutex deadlock (add 2 missing exit calls)
lttng-tools:(Tue Sep 18) 4adabd6 Fix: Remove LPOLLNVAL from consumer metadata revents
babeltrace: (Thu Sep 13) f546472 Fix: Documentation cleanup

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Updated by Mathieu Desnoyers over 11 years ago

Project changed from LTTng-UST to LTTng-tools

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Updated by David Goulet over 11 years ago

Status changed from New to Confirmed
Assignee set to David Goulet
Priority changed from Normal to High
Target version set to 2.1 stable

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Updated by David Goulet over 11 years ago

Status changed from Confirmed to Feedback

So actually I don't think this is an error.

Enabling an event and a filter is two different API calls so the event is first enabled successfully but the filter is wrong so the fix is simply to retry lttng enable-event with the right filter and it works.

I'm not sure I can easily disable or even delete an event on a wrong filter... Rerun the command with the correct filter is I think the correct behavior and thing to do.

Thought?

Thanks

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Updated by Mathieu Desnoyers over 11 years ago

Yes, this is a bug. This is an unexpected behavior on the command line.

If we see that setting the filter triggers an error, we should disable the event.

This is an issue at the command line level, not at the API level.

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Updated by David Goulet over 11 years ago

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I'm not sure to be honest.

There is a use case where enabling let say event ust-eventA, tracing
and then later on setting a filter on it. Disabling it seems to me a
bit harsh and not a right behavior for an already good enabled event.

David

bugs@lttng.org:

Issue #343 has been updated by Mathieu Desnoyers.

Yes, this is a bug. This is an unexpected behavior on the command
line.

If we see that setting the filter triggers an error, we should
disable the event.

This is an issue at the command line level, not at the API level.

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Updated by Mathieu Desnoyers over 11 years ago

That's a case where there has been a reported error when setting up the filter. It's OK to be harsh and disable a previously enabled event in that kind of condition. You might want to let the user know that the event id disabled due to the filter error.

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Updated by David Goulet over 11 years ago

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I guess we could simply do a lttng_disable_event if an error
occured... that makes sense to me.

I'll keep this bug alive and fix this for 2.1-stable.

Thanks
David
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