Description of problem: When two separate threads load TLS library functions sequentially, one thread will be very slow due to a generation counter mismatch (and thus glibc thinking it needs to reallocate memory for it).

Version-Release number of selected component (if applicable):
2.28-164.el8.x86_64

How reproducible: 100%

Steps to Reproduce:
1. yum install gcc gcc-c++ make glibc-devel openssl-devel
2. Unzip shell archive with test case.
3. Run "make".
4. Execute program "tls-test".

Actual results:
One thread is slower than the other to access TLS variables:

none loaded
main normal variable : 554.770ms
main thread-local variable : 578.829ms
lib1 loaded
main normal variable : 536.941ms
main thread-local variable : 504.300ms
lib1 variable : 2079.362ms
lib2 loaded
main normal variable : 451.575ms
main thread-local variable : 434.603ms
lib1 variable : 5567.543ms
lib2 accessed
main normal variable : 424.644ms
main thread-local variable : 429.140ms
lib1 variable : 1911.933ms

Expected results: lib1 variable access time is consistent.

Additional info:

• Issue was first noted in 2016 (https://patchwork.ozlabs.org/project/glibc/patch/1465309688.1188.19.camel@mailbox.tu-dresden.de/), and a patch was proposed.