> Date: Sun, 27 Jun 2021 13:36:03 +0000 > From: Klemens Nanni <[email protected]> > > On Sat, Jun 12, 2021 at 11:54:58PM -0700, Greg Steuck wrote: > > I started with a failing test for Haskell network package on 6.9-current > > amd64 > > (cabal get network-3.1.2.1 && cabal v2-test) > > > > network-3.1.2.1/build/spec/spec --match > > "/Network.Socket.ByteString/recvMsg/works well/" > > > > tests/Network/Socket/ByteStringSpec.hs:209:21: > > 1) Network.Socket.ByteString.recvMsg works well > > expected: MsgFlag {fromMsgFlag = 0} > > but got: MsgFlag {fromMsgFlag = 128} > > > > ktrace says: > > > > 47649 spec CALL sendto(14,0x8a2126e838c,0x16,0,0x8a4a3622df0,0x10) > > 47649 spec STRU struct sockaddr { AF_INET, 127.0.0.1:9486 } > > 47649 spec GIO fd 14 wrote 22 bytes > > "This is a test message" > > 47649 spec RET sendto 22/0x16 > > 47649 spec CALL > > futex(0x8a4aef6f930,0x81<FUTEX_WAIT|FUTEX_PRIVATE_FLAG>,1,0,0) > > 47649 spec STRU struct kevent { ident=13, filter=EVFILT_READ, > > flags=0x11<EV_ADD|EV_ONESHOT>, fflags=0<>, data=38, udata=0x0 } > > 47649 spec RET kevent 1 > > 47649 spec CALL recvmsg(13,0x8a4a3622c50,0) > > 47649 spec GIO fd 13 read 22 bytes > > "This is a test message" > > 47649 spec STRU struct sockaddr { AF_INET, 127.0.0.1:12293 } > > 47649 spec STRU struct msghdr { name=0x8a4a3622b70, namelen=16, > > iov=0x8a4a3622c30, iovlen=1, control=0x8a4a3622c10, controllen=0, > > flags=0x80<MSG_DONTWAIT> } > > 47649 spec STRU struct iovec { base=0x8a4a3622666, len=1002 } > > 47649 spec RET recvmsg 22/0x16 > > > > This seems to contradict recvmsg(2) which doesn't list MSG_DONTWAIT as a > > possible value of the flags. Would this be useful as a C regress test? > > Looks like this was missed in sys/kern/uipc_syscalls.c revision 1.178 > > date: 2018/07/30 12:22:14; author: mpi; state: Exp; lines: +10 -18; > commitid: K43aQe66cQkEOSbc; > Use FNONBLOCK instead of SS_NBIO to check/indicate that the I/O mode > for sockets is non-blocking. > > This allows us to G/C SS_NBIO. Having to keep the two flags in sync > in a mp-safe way is complicated. > > This change introduce a behavior change in sosplice(), it can now > always block. However this should not matter much due to the socket > lock being taken beforhand. > > bluhm@, benno@, visa@ > > Wording taken from mpi's commit message which is exactly what recvit() > does in one place, i.e. > > if (fp->f_flag & FNONBLOCK) > mp->msg_flags |= MSG_DONTWAIT; > > > Here's the documentation bits for it? > Feedback? Objections? OK?
I think this points out that diff wasn't quite right. I mean, changing the man page doesn't fix the Haskell test does it? > Index: lib/libc/sys/recv.2 > =================================================================== > RCS file: /cvs/src/lib/libc/sys/recv.2,v > retrieving revision 1.47 > diff -u -p -r1.47 recv.2 > --- lib/libc/sys/recv.2 11 Jan 2019 06:10:13 -0000 1.47 > +++ lib/libc/sys/recv.2 27 Jun 2021 13:30:33 -0000 > @@ -248,6 +248,8 @@ for ancillary data. > Indicates that the packet was received as broadcast. > .It Dv MSG_MCAST > Indicates that the packet was received as multicast. > +.It Dv MSG_DONTWAIT > +Indicates that the I/O mode for the socket is non-blocking. > .El > .Sh RETURN VALUES > These calls return the number of bytes received, or \-1 if an error occurred. > >
