Add an assertion that nfssvc() isn't called with Giant.

Add two additional pairs of assertions, one at the end of the NFS
server event loop, and one one exit from the NFS daemon, that
assert that if debug.mpsafenet is enabled, Giant is not held, and
that if it is not enabled, Giant will be held.  This is intended
to support debugging scenarios where Giant is "leaked" during NFS
processing.

1 files changed, 10 insertions, 0 deletions

diff --git a/sys/nfsserver/nfs_syscalls.c b/sys/nfsserver/nfs_syscalls.c
index 5a6e2e5..3c6bd56 100644
--- a/sys/nfsserver/nfs_syscalls.c
+++ b/sys/nfsserver/nfs_syscalls.c
@@ -134,6 +134,8 @@ nfssvc(struct thread *td, struct nfssvc_args *uap)
 	struct nfsd_args nfsdarg;
 	int error;
 
+	KASSERT(!mtx_owned(&Giant), ("nfssvc(): called with Giant"));
+
 #ifdef MAC
 	error = mac_check_system_nfsd(td->td_ucred);
 	if (error)
@@ -550,8 +552,16 @@ nfssvc_nfsd(struct thread *td)
 			nfsd->nfsd_slp = NULL;
 			nfsrv_slpderef(slp);
 		}
+		KASSERT(!(debug_mpsafenet == 0 && !mtx_owned(&Giant)),
+		    ("nfssvc_nfsd(): debug.mpsafenet=0 && !Giant"));
+		KASSERT(!(debug_mpsafenet == 1 && mtx_owned(&Giant)),
+		    ("nfssvc_nfsd(): debug.mpsafenet=1 && Giant"));
 	}
 done:
+	KASSERT(!(debug_mpsafenet == 0 && !mtx_owned(&Giant)),
+	    ("nfssvc_nfsd(): debug.mpsafenet=0 && !Giant"));
+	KASSERT(!(debug_mpsafenet == 1 && mtx_owned(&Giant)),
+	    ("nfssvc_nfsd(): debug.mpsafenet=1 && Giant"));
 	TAILQ_REMOVE(&nfsd_head, nfsd, nfsd_chain);
 	splx(s);
 	free((caddr_t)nfsd, M_NFSD);