On Tue, 2013-10-01 at 04:27 +0100, Al Viro wrote: > On Mon, Sep 30, 2013 at 07:02:23PM -0700, Linus Torvalds wrote: > > > Shouldn't a cmpxchg() in just the dup2 code solve that? > > > > If the old value was NULL, you'd have to repeat and go back and see if > > the open_fds[] bit had been cleared in the meantime (ie it's NULL not > > because somebody else is busy installing it, but because somebody just > > uninstalled it). > > Yechh... Under ->file_lock (in do_dup2()), hopefully? Or you'll get > all kinds of fun with close() thrown into the game, as well... > > > But yeah, I do agree that that sounds nasty and a complication I > > hadn't even thought about. dup2() does violate our normal "let's > > pre-allocate the fd slot" rule. Ugh. > > Hell knows... Descriptor handling *is* pretty well isolated these > days, so it just might be doable without disrupting the living hell > out of anything else. fs/file.c is pretty much it - everything else > goes through it. I have a patch mostly working here, and pretty short. I'll do proper tests before posting it tomorrow. fs/fcntl.c | 7 ++----- fs/file.c | 17 +++++++++++++---- fs/open.c | 21 +++++++++++++++++---- include/linux/fdtable.h | 1 + 4 files changed, 33 insertions(+), 13 deletions(-) Thanks ! -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
