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libthr rtld locks: do not leak URWLOCK_READ_WAITERS into child
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Authored by kib on May 20 2023, 8:28 AM.
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Details

Summary
Since there is only the current thread in the child, no pending readers
exist.  Clear the bit, since it confuses future attempts to acquire
write ownership of the rtld locks, due to URWLOCK_PREFER_READERS flag.

PR:     271490

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rG FreeBSD src repository
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kib requested review of this revision.May 20 2023, 8:28 AM
kib added a reviewer: markj.

To be future-proof, clear all state about pending writers and readers.

It would be nice to turn the test case from PR 271490 into a regression test case, either in the base system or in stress2.

lib/libthr/thread/thr_rtld.c
161

Perhaps use __predict_false here.

This revision is now accepted and ready to land.May 22 2023, 1:32 PM