libexec/ld.elf_so/rtld.c: revision 1.205
libexec/ld.elf_so/rtld.h: revision 1.140
libexec/ld.elf_so/symbols.map: revision 1.3
libexec/ld.elf_so/symbols.map: revision 1.4
lib/libc/gen/pthread_atfork.c: revision 1.13
lib/libc/gen/pthread_atfork.c: revision 1.14
libexec/ld.elf_so/rtld.h: revision 1.139
libexec/ld.elf_so/rtld.c: revision 1.204
Introduce intermediate locking for fork, so that the dynamic linker is
in a consistent state. This most importantly avoids races between dlopen
and friends and fork, potentially resulting in dead locks in the child
when it itself tries to acquire locks.
Rename __atomic_fork to __locked_fork and give it &errno as argument.
rtld and libc use different storage, so the initial version would
incorrectly report the failure reason for fork().
There is still a small race condition inside ld.elf_so as it doesn't use
thread-safe errno internally, but that's a more contained internal
issue.
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