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HPCC-33655 Fix possible LOCK_EVASION in dafileserver #19623

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HPCC-33655 Fix possible LOCK_EVASION in dafileserver #19623

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streeterd
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@streeterd streeterd commented Mar 14, 2025 •
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@streeterd streeterd self-assigned this Mar 14, 2025
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Jira Issue: https://hpccsystems.atlassian.net//browse/HPCC-33655

Jirabot Action Result:
Workflow Transition To: Merge Pending
Updated PR

@streeterd streeterd marked this pull request as ready for review March 18, 2025 10:08
@streeterd streeterd requested review from jakesmith and Copilot March 18, 2025 10:08
Copilot
Copilot AI reviewed Mar 18, 2025
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Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

jakesmith
jakesmith reviewed Mar 31, 2025
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@streeterd - please see comments.

fs/dafsserver/dafsserver.cpp Outdated
clientcounttick = msTick();
MaxClientCount = ClientCount;
if (closedclients)
if (msTick() - clientcounttick > 1000 * 60 * 60)
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the write to clientcounttick was tested outside the crit, and altered in it, but it didn't need protecting. ClientCountSect is really only protecting concurrency to ClientCount and MaxClientCount.
It would be better to move the clientcounttick, to just after the if, and scope this crit around the ClitnCount/MaxClientCount code, i.e.:

            clientcounttick = msTick();
            {
                CriticalBlock block(ClientCountSect);
                if (TF_TRACE_CLIENT_STATS && (ClientCount || MaxClientCount))
                    PROGLOG("Client count = %d, max = %d", ClientCount, MaxClientCount);
                MaxClientCount = ClientCount;
            }

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It would also be worth noting somewhere that clientcounttick and closedclients are members only touched/read by checkTimeout() that is not contended itself.

@streeterd streeterd requested review from Copilot and jakesmith March 31, 2025 15:33
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Copilot wasn't able to review any files in this pull request.

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  • fs/dafsserver/dafsserver.cpp: Language not supported

jakesmith
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@streeterd - 1 minor issue.

fs/dafsserver/dafsserver.cpp
if (TF_TRACE_CLIENT_STATS)
PROGLOG("Closed client count = %d", closedclients);
closedclients = 0;
}
}
}
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other end of block brace added, not needed.

@streeterd streeterd requested review from Copilot and jakesmith March 31, 2025 16:06
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Copilot wasn't able to review any files in this pull request.

Files not reviewed (1)
  • fs/dafsserver/dafsserver.cpp: Language not supported

@streeterd streeterd requested a review from Copilot March 31, 2025 16:06
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Copilot wasn't able to review any files in this pull request.

Files not reviewed (1)
  • fs/dafsserver/dafsserver.cpp: Language not supported

jakesmith
jakesmith reviewed Mar 31, 2025
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@streeterd - 1 trivial comment, can yo address and squash?

fs/dafsserver/dafsserver.cpp Outdated
{
CriticalBlock block(ClientCountSect);
if (TF_TRACE_CLIENT_STATS && (ClientCount || MaxClientCount))
PROGLOG("Client count = %d, max = %d", ClientCount, MaxClientCount);
clientcounttick = msTick();
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trivial: should have made observation before - would be more logical to reset this time at the end of the if block.

@streeterd
HPCC-33655 Fix possible LOCK_EVASION in dafileserver
1b03e84 
Ensure clientcounttick is tested and reset outside of ClientCountSect.

Signed-off-by: Dave Streeter <[email protected]>
@streeterd streeterd force-pushed the HPCC-33655_Fix_possible_LOCK_EVASION_in_dafileserver branch from a22ce1b to 1b03e84 Compare March 31, 2025 17:11
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@jakesmith PR comment implemented and commits squashed

jakesmith
jakesmith approved these changes Apr 1, 2025
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@streeterd - looks good.

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