On 01/20/2015 09:25 AM, Daniel Mack wrote: > Hi Michael, > > On 01/20/2015 09:09 AM, Michael Kerrisk (man-pages) wrote: >> On 11/30/2014 06:23 PM, Florian Weimer wrote: >>> * David Herrmann: >>> >>>> On Sun, Nov 30, 2014 at 10:02 AM, Florian Weimer <fw@xxxxxxxxxxxxx> wrote: >>>>> * Greg Kroah-Hartman: >>>>> >>>>>> +7.4 Receiving messages >>> >>>>> What happens if this is not possible because the file descriptor limit >>>>> of the processes would be exceeded? EMFILE, and the message will not >>>>> be received? >>>> >>>> The message is returned without installing the FDs. This is signaled >>>> by EMFILE, but a valid pool offset. >>> >>> Oh. This is really surprising, so it needs documentation. But it's >>> probably better than the alternative (return EMFILE and leave the >>> message stuck, so that you receive it immediately again—this behavior >>> makes non-blocking accept rather difficult to use correctly). >> >> So, was this point in the end explicitly documented? I not >> obvious that it is documented in the revised kdbus.txt that >> Greg K-H sent out 4 days ago. > > No, we've revisited this point and changed the kernel behavior again in > v3. We're no longer returning -EMFILE in this case, but rather set > KDBUS_RECV_RETURN_INCOMPLETE_FDS in a new field in the receive ioctl > struct called 'return_flags'. We believe that's a nicer way of signaling > specific errors. The message will carry -1 for all FDs that failed to > get installed, so the user can actually see which one is missing. > > That's also documented in kdbus.txt, but we missed putting it into the > Changelog - sorry for that. Thanks for the info, Daniel. Cheers, Michael -- 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-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
