Em Mon, Jun 16, 2014 at 11:58:51AM +0200, Michael Kerrisk (man-pages) escreveu: > Hi Arnaldo, > > Things have gone quiet ;-). What's the current state of this patch? Yeah, I kept meaning to prod the other people on this thread about what they thought about my last messages, patches, etc. :-) Can I have acked-by or even tested-by on those? Is it ok? - Arnaldo > Thanks, > > Michael > > > On Thu, May 29, 2014 at 4:17 PM, Arnaldo Carvalho de Melo > <acme@xxxxxxxxxxxxxxxxxx> wrote: > > Em Thu, May 29, 2014 at 02:06:04PM +0000, David Laight escreveu: > >> From: 'Arnaldo Carvalho de Melo' > >> ... > >> > > I remember some discussions from an XNET standards meeting (I've forgotten > >> > > exactly which errors on which calls were being discussed). > >> > > My recollection is that you return success with a partial transfer > >> > > count for ANY error that happens after some data has been transferred. > >> > > The actual error will be returned when it happens again on the next > >> > > system call - Note the AGAIN, not a saved error. > > > >> > A saved error, for the right entity, in the recvmmsg case, that > >> > basically is batching multiple recvmsg syscalls, doesn't sound like a > >> > problem, i.e. the idea is to, as much as possible, mimic what multiple > >> > recvmsg calls would do, but reduce its in/out kernel (and inside kernel > >> > subsystems) overhead. > > > >> > Perhaps we can have something in between, i.e. for things like EFAULT, > >> > we should report straight away, effectively dropping whatever datagrams > >> > successfully received in the current batch, do you agree? > > > >> Not unreasonable - EFAULT shouldn't happen unless the application > >> is buggy. > > > > Ok. > > > >> > For transient errors the existing mechanism, fixed so that only per > >> > socket errors are saved for later, as today, could be kept? > > > >> I don't think it is ever necessary to save an errno value for the > >> next system call at all. > >> Just process the next system call and see what happens. > > > >> If the call returns with less than the maximum number of datagrams > >> and with a non-zero timeout left - then the application can infer > >> that it was terminated by an abnormal event of some kind. > >> This might be a signal. > > > > Then it could use getsockopt(SO_ERROR) perhaps? I.e. we don't return the > > error on the next call, but we provide a way for the app to retrieve the > > reason for the smaller than expected batch? > > > >> I'm not sure if an icmp error on a connected datagram socket could > >> generate a 'disconnect'. It might happen if the interface is being > >> used for something like SCTP. > >> In either case the next call will detect the error. > > > > - Arnaldo > > > > -- > Michael Kerrisk > Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ > Linux/UNIX System Programming Training: http://man7.org/training/ > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- 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
