Date: Wed, 6 Mar 2024 07:50:48 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 2ce23b1f7672 - main - libc posix_spawn(): explain why rtld can be used after fork Message-ID: <202403060750.4267omhK054444@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=2ce23b1f76721e44646fc98ba4e24a113a6d5972 commit 2ce23b1f76721e44646fc98ba4e24a113a6d5972 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2024-03-06 07:24:22 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2024-03-06 07:25:14 +0000 libc posix_spawn(): explain why rtld can be used after fork Sponsored by: The FreeBSD Foundation MFC after: 1 week --- lib/libc/gen/posix_spawn.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/lib/libc/gen/posix_spawn.c b/lib/libc/gen/posix_spawn.c index d405517ba68d..ee2ce05ff317 100644 --- a/lib/libc/gen/posix_spawn.c +++ b/lib/libc/gen/posix_spawn.c @@ -325,6 +325,11 @@ do_posix_spawn(pid_t *pid, const char *path, * ideal vfork(2) if we get an EINVAL from rfork -- this should only * happen with newer libc on older kernel that doesn't accept * RFSPAWN. + * + * Combination of vfork() (or its equivalent rfork() form) and + * a special property of the libthr rtld locks ensure that + * rtld is operational in the child. In particular, libthr + * rtld locks do not store owner' tid into the lock word. */ #ifdef _RFORK_THREAD_STACK_SIZE /*
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