svn commit: r316694 - head/sys/rpc
Rick Macklem
rmacklem at FreeBSD.org
Mon Apr 10 22:47:20 UTC 2017
Author: rmacklem
Date: Mon Apr 10 22:47:18 2017
New Revision: 316694
URL: https://svnweb.freebsd.org/changeset/base/316694
Log:
Fix a crash during unmount of an NFSv4.1 mount.
Larry Rosenman reported a crash on freebsd-current@ which was caused by
a premature release of the krpc backchannel socket structure.
I believe this was caused by a race between the SVC_RELEASE() in clnt_vc.c
and the xprt_unregister() in the higher layer (clnt_rc.c), which tried
to lock the mutex in the xprt structure and crashed.
This patch fixes this by removing the xprt_unregister() in the clnt_vc
layer and allowing this to always be done by the clnt_rc (higher reconnect
layer).
Reported by: ler at lerctr.org
Tested by: ler at letctr.org
MFC after: 2 weeks
Modified:
head/sys/rpc/clnt_rc.c
head/sys/rpc/clnt_vc.c
Modified: head/sys/rpc/clnt_rc.c
==============================================================================
--- head/sys/rpc/clnt_rc.c Mon Apr 10 22:46:34 2017 (r316693)
+++ head/sys/rpc/clnt_rc.c Mon Apr 10 22:47:18 2017 (r316694)
@@ -450,7 +450,6 @@ clnt_reconnect_control(CLIENT *cl, u_int
case CLSET_BACKCHANNEL:
xprt = (SVCXPRT *)info;
- SVC_ACQUIRE(xprt);
xprt_register(xprt);
rc->rc_backchannel = info;
break;
Modified: head/sys/rpc/clnt_vc.c
==============================================================================
--- head/sys/rpc/clnt_vc.c Mon Apr 10 22:46:34 2017 (r316693)
+++ head/sys/rpc/clnt_vc.c Mon Apr 10 22:47:18 2017 (r316694)
@@ -790,7 +790,7 @@ clnt_vc_destroy(CLIENT *cl)
sx_xlock(&xprt->xp_lock);
mtx_lock(&ct->ct_lock);
xprt->xp_p2 = NULL;
- xprt_unregister(xprt);
+ sx_xunlock(&xprt->xp_lock);
}
if (ct->ct_socket) {
@@ -800,10 +800,6 @@ clnt_vc_destroy(CLIENT *cl)
}
mtx_unlock(&ct->ct_lock);
- if (xprt != NULL) {
- sx_xunlock(&xprt->xp_lock);
- SVC_RELEASE(xprt);
- }
mtx_destroy(&ct->ct_lock);
if (so) {
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