guenther@ pointed out during a2k17 that nfsrv_rcv() already has a way to
not re-enter the socket layer. Instead of doing soreceive() directly in
the receiving path, we notify and wakeup nfsd(8) to do it.
I'd like to do that unconditionally to fix one of the blocking
recursions.
I just finished a bake a build on NFS. I'd appreciate more tests an
oks.
Index: kern/uipc_socket.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_socket.c,v
retrieving revision 1.176
diff -u -p -r1.176 uipc_socket.c
--- kern/uipc_socket.c 1 Feb 2017 20:59:47 -0000 1.176
+++ kern/uipc_socket.c 6 Feb 2017 14:33:48 -0000
@@ -1530,12 +1530,8 @@ sorwakeup(struct socket *so)
return;
#endif
sowakeup(so, &so->so_rcv);
- if (so->so_upcall) {
- /* XXXSMP breaks atomicity */
- rw_exit_write(&netlock);
+ if (so->so_upcall)
(*(so->so_upcall))(so, so->so_upcallarg, M_DONTWAIT);
- rw_enter_write(&netlock);
- }
}
void
Index: nfs/nfs_socket.c
===================================================================
RCS file: /cvs/src/sys/nfs/nfs_socket.c,v
retrieving revision 1.112
diff -u -p -r1.112 nfs_socket.c
--- nfs/nfs_socket.c 19 Dec 2016 08:36:50 -0000 1.112
+++ nfs/nfs_socket.c 6 Feb 2017 14:16:39 -0000
@@ -1570,26 +1570,15 @@ nfsrv_rcv(struct socket *so, caddr_t arg
if ((slp->ns_flag & SLP_VALID) == 0)
return;
-#ifdef notdef
- /*
- * Define this to test for nfsds handling this under heavy load.
- */
+
+ /* Defer soreceive() to an nfsd. */
if (waitflag == M_DONTWAIT) {
- slp->ns_flag |= SLP_NEEDQ; goto dorecs;
+ slp->ns_flag |= SLP_NEEDQ;
+ goto dorecs;
}
-#endif
+
auio.uio_procp = NULL;
if (so->so_type == SOCK_STREAM) {
- /*
- * If there are already records on the queue, defer soreceive()
- * to an nfsd so that there is feedback to the TCP layer that
- * the nfs servers are heavily loaded.
- */
- if (slp->ns_rec && waitflag == M_DONTWAIT) {
- slp->ns_flag |= SLP_NEEDQ;
- goto dorecs;
- }
-
/*
* Do soreceive().
*/
Index: conf/GENERIC
===================================================================
RCS file: /cvs/src/sys/conf/GENERIC,v
retrieving revision 1.239
diff -u -p -r1.239 GENERIC
--- conf/GENERIC 25 Jan 2017 00:48:36 -0000 1.239
+++ conf/GENERIC 6 Feb 2017 14:36:04 -0000
@@ -59,7 +59,7 @@ option PPP_DEFLATE
option PIPEX # Ppp IP EXtension, for npppd
option MROUTING # Multicast router
option MPLS # Multi-Protocol Label Switching
-option BFD # Bi-directional Forwarding Detection
+#option BFD # Bi-directional Forwarding Detection
#mpath0 at root # SCSI Multipathing
#scsibus* at mpath?
