https://bugs.kde.org/show_bug.cgi?id=428909
--- Comment #10 from Paul Floyd <pjfl...@wanadoo.fr> ---
I'll attempt to add as many explanations as possible.
First, the true nature of the problem on Fedora 33. For some very bizarre
reason, pthread_cond_destroy is no longer in libpthread:
paulf> nm /lib64/libpthread.so.0 | grep cond_destroy
U __pthread_cond_destroy@@GLIBC_PRIVATE
instead it is in libc
paulf> nm /lib64/libc.so.6 | grep cond_destroy
[snip loads more]
0000000000086440 T pthread_cond_destroy@GLIBC_2.2.5
00000000000869f0 T pthread_cond_destroy@@GLIBC_2.3.2
DRD and Helgrind are doing essentially the sme thing for the intercepts, but
differ a bit in the details. For DRD, see drd_pthread_intercepts.c where the
PTH_FUNCS macro generates 3 wrapper functions covering "name", "name@*" and
"name$*". Bart extended this for both libc and libpthread (but only libthread
with MUSL)
Hence I now see
paulf> nm vgpreload_drd-amd64-linux.so | grep pthread | grep cond | grep
destroy
U pthread_cond_destroy
0000000000017c90 T _vgw00000ZZ_libcZdsoZa_pthreadZucondZudestroy
0000000000017f70 T _vgw00000ZZ_libcZdsoZa_pthreadZucondZudestroyZAZa
0000000000018250 T _vgw00000ZZ_libcZdsoZa_pthreadZucondZudestroyZDZa
0000000000017e00 T _vgw00000ZZ_libpthreadZdsoZd0_pthreadZucondZudestroy
00000000000180e0 T _vgw00000ZZ_libpthreadZdsoZd0_pthreadZucondZudestroyZAZa
00000000000183c0 T _vgw00000ZZ_libpthreadZdsoZd0_pthreadZucondZudestroyZDZa
Helgrind is more on a case by case basis (which means the code is a bit longer
but only the required wrappers are generated). So now I see
paulf> nm vgpreload_helgrind-amd64-linux.so | grep pthread | grep cond | grep
destroy
000000000000a4f9 t pthread_cond_destroy_WRK
000000000000d87d W _vgw00000ZZ_libcZdsoZa_pthreadZucondZudestroyZAZa
000000000000d87d T _vgw00000ZZ_libpthreadZdsoZd0_pthreadZucondZudestroyZAZa
The difference here is that DRD has 3 separate functions whilst Helgrind has
just one plus an alias. They both work the same way with the redirection
mechanism - they're just symbols and calling them does the same thing.
The differences between Linux and other OSes (Solaris, FreeBSD and macOS)
concern the names of the libc / libppthread libraries and the mangling used).
Finally, MUSL. I'm not sure if this is strictly necessary (I don't have a
system to test on, perhaps I will spin up yet another Virtual Box ...). It's
certainly more consistent with DRD.
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