It claims the issue is only relevant for shared descriptor tables which is of no concern for POSIX (but then is POSIX of concern to anyone today?), which I presume predates standarized threading. The comment also mentions the following systems: - OpenBSD installing a larval file -- this remains accurate - FreeBSD returning EBADF -- not accurate, the system uses the same idea as OpenBSD - NetBSD "deadlocks in amusing ways" -- their solution looks Solaris-inspired (not a compliment) and I would not be particularly surprised if it indeed deadlocked, in amusing ways or otherwise I don't believe mentioning any of these adds anything and the statement about the issue not being POSIX-relevant is outdated. dup2 description in POSIX still does not mention the problem. Just shorten the comment and be done with it. Signed-off-by: Mateusz Guzik <mjguzik@xxxxxxxxx> --- I'm pretty sure the comment adds nothing in the current form, but I'm not going to argue about it. fs/file.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/fs/file.c b/fs/file.c index d065a24980da..ad8aabc08122 100644 --- a/fs/file.c +++ b/fs/file.c @@ -1258,17 +1258,9 @@ __releases(&files->file_lock) /* * We need to detect attempts to do dup2() over allocated but still - * not finished descriptor. NB: OpenBSD avoids that at the price of - * extra work in their equivalent of fget() - they insert struct - * file immediately after grabbing descriptor, mark it larval if - * more work (e.g. actual opening) is needed and make sure that - * fget() treats larval files as absent. Potentially interesting, - * but while extra work in fget() is trivial, locking implications - * and amount of surgery on open()-related paths in VFS are not. - * FreeBSD fails with -EBADF in the same situation, NetBSD "solution" - * deadlocks in rather amusing ways, AFAICS. All of that is out of - * scope of POSIX or SUS, since neither considers shared descriptor - * tables and this condition does not arise without those. + * not finished descriptor. + * + * POSIX is silent on the issue, we return -EBUSY. */ fdt = files_fdtable(files); fd = array_index_nospec(fd, fdt->max_fds); -- 2.43.0
