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Fix a crash during unmount of an NFSv4.1 mount.

Browse Source 
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@lerctr.org
Tested by:	ler@letctr.org
MFC after:	2 weeks
This commit is contained in:
Rick Macklem 2017-04-10 22:47:18 +00:00
parent fb55679151
commit 34f1fddb1e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=316694
2 changed files with 1 additions and 6 deletions
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1
sys/rpc/clnt_rc.c
View File

@ -450,7 +450,6 @@ clnt_reconnect_control(CLIENT *cl, u_int request, void *info)
case CLSET_BACKCHANNEL:
xprt = (SVCXPRT *)info;
SVC_ACQUIRE(xprt);
xprt_register(xprt);
rc->rc_backchannel = info;
break;

6
sys/rpc/clnt_vc.c
View File

@ -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) {