Hi Lukas On Fri, Oct 7, 2011 at 9:09 AM, Lukas Czerner <lczerner@xxxxxxxxxx> wrote: > On Fri, 7 Oct 2011, Michael Kerrisk wrote: > >> Lukas, >> >> On Mon, Aug 29, 2011 at 2:26 PM, Lukas Czerner <lczerner@xxxxxxxxxx> wrote: >> > When dealing with sockets, we have to be sure that there is no recv >> > still blocking on it on another thread, otherwise it might block forever, >> > since no more messages will be send via the socket. We should advice to >> > use shutdown before closing socket. >> >> I'm looking into this now. The picture may be more complex than this. >> Tell me, so you have a Solaris system available for testing? >> >> Thanks, > > Hi Michael, > > Thanks for looking into this. Unfortunately I do not have any Solaris system > for testing, that was a customer report. His complaint was mainly not because > the behaviour on Linux differs, but because this was not documented anywhere. Okay. I will see if I can find a test system somewhere. (The system I used to use seems to have gone away.) Just FYI: I confirmed what you are seeing, but the issue seems more general: basically, closing a file descriptor in one thread while reading in another thread does not cause the read operation to terminate (it will still read data if/when it becomes available). By the way, I'm wondering about creating a small repo of test programs. I might like to add a modified version of your test program to that repo. Can you put that code under a Free License and supply a copyright? Thanks, Michael >> > Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx> >> > --- >> > man2/close.2 | 7 +++++++ >> > 1 files changed, 7 insertions(+), 0 deletions(-) >> > >> > diff --git a/man2/close.2 b/man2/close.2 >> > index a2a2961..02472f3 100644 >> > --- a/man2/close.2 >> > +++ b/man2/close.2 >> > @@ -114,6 +114,13 @@ other threads in the same process. >> > Since a file descriptor may be reused, >> > there are some obscure race conditions >> > that may cause unintended side effects. >> > +.PP >> > +When dealing with sockets, you have to be sure that there is no >> > +.BR recv (2) >> > +still blocking on it on another thread, otherwise it might block forever, >> > +since no more messages will be send via the socket. Be sure to use >> > +.BR shutdown (2) >> > +to shut down all parts the connection before closing the socket. >> > .\" Date: Tue, 4 Sep 2007 13:57:35 +0200 >> > .\" From: Fredrik Noring <noring@xxxxxxxxxx> >> > .\" One such race involves signals and ERESTARTSYS. If a file descriptor >> > -- >> > 1.7.4.4 >> > >> > >> >> >> >> > > -- -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
