On Fri, Mar 13, 2015 at 12:42 PM, Josh Triplett <josh@xxxxxxxxxxxxxxxx> wrote: > On Fri, Mar 13, 2015 at 04:05:29PM +0000, David Drysdale wrote: >> On Fri, Mar 13, 2015 at 1:40 AM, Josh Triplett <josh@xxxxxxxxxxxxxxxx> wrote: >> > This patch series introduces a new clone flag, CLONE_FD, which lets the caller >> > handle child process exit notification via a file descriptor rather than >> > SIGCHLD. CLONE_FD makes it possible for libraries to safely launch and manage >> > child processes on behalf of their caller, *without* taking over process-wide >> > SIGCHLD handling (either via signal handler or signalfd). >> >> Hi Josh, >> >> From the overall description (i.e. I haven't looked at the code yet) >> this looks very interesting. However, it seems to cover a lot of the >> same ground as the process descriptor feature that was added to FreeBSD >> in 9.x/10.x: >> https://www.freebsd.org/cgi/man.cgi?query=pdfork&sektion=2 > > Interesting. > >> I think it would ideally be nice for a userspace library developer to be >> able to do subprocess management (without SIGCHLD) in a similar way >> across both platforms, without lots of complicated autoconf shenanigans. >> >> So could we look at the overlap and seeing if we can come up with >> something that covers your requirements and also allows for something >> that looks like FreeBSD's process descriptors? > > Agreed; however, I think it's reasonable to provide appropriate Linux > system calls, and then let glibc or libbsd or similar provide the > BSD-compatible calls on top of those. I don't think the kernel > interface needs to exactly match FreeBSD's, as long as it's a superset > of the functionality. We need to be careful with things like read(2), though. It's hard to write a glibc function that makes read(2) do something other than what the kernel thinks. Similarly, poll(2) is defined by the kernel. It would be really nice to be consistent here. --Andy -- 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
