Date: Mon, 27 Sep 2010 02:30:56 +0000 (UTC) From: Rick Macklem <rmacklem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r213191 - stable/8/sys/fs/nfsserver Message-ID: <201009270230.o8R2UupC009894@svn.freebsd.org>
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Author: rmacklem Date: Mon Sep 27 02:30:56 2010 New Revision: 213191 URL: http://svn.freebsd.org/changeset/base/213191 Log: MFC: r212443 This patch applies one of the two fixes suggested by zack.kirsch at isilon.com for a race between nfsrv_freeopen() and nfsrv_getlockfile() in the experimental NFS server that he found during testing. Although nfsrv_freeopen() holds a sleep lock on the lock file structure when called with cansleep != 0, nfsrv_getlockfile() could still search the list, once it acquired the NFSLOCKSTATE() mutex. I believe that acquiring the mutex in nfsrv_freeopen() fixes the race. Modified: stable/8/sys/fs/nfsserver/nfs_nfsdstate.c Directory Properties: stable/8/sys/ (props changed) stable/8/sys/amd64/include/xen/ (props changed) stable/8/sys/cddl/contrib/opensolaris/ (props changed) stable/8/sys/contrib/dev/acpica/ (props changed) stable/8/sys/contrib/pf/ (props changed) stable/8/sys/dev/xen/xenpci/ (props changed) Modified: stable/8/sys/fs/nfsserver/nfs_nfsdstate.c ============================================================================== --- stable/8/sys/fs/nfsserver/nfs_nfsdstate.c Mon Sep 27 02:09:25 2010 (r213190) +++ stable/8/sys/fs/nfsserver/nfs_nfsdstate.c Mon Sep 27 02:30:56 2010 (r213191) @@ -1085,8 +1085,11 @@ nfsrv_freeopen(struct nfsstate *stp, vno * associated with the open. * If there are locks associated with the open, the * nfslockfile structure can be freed via nfsrv_freelockowner(). - * (That is why the call must be here instead of after the loop.) + * Acquire the state mutex to avoid races with calls to + * nfsrv_getlockfile(). */ + if (cansleep != 0) + NFSLOCKSTATE(); if (lfp != NULL && LIST_EMPTY(&lfp->lf_open) && LIST_EMPTY(&lfp->lf_deleg) && LIST_EMPTY(&lfp->lf_lock) && LIST_EMPTY(&lfp->lf_locallock) && LIST_EMPTY(&lfp->lf_rollback) && @@ -1096,6 +1099,8 @@ nfsrv_freeopen(struct nfsstate *stp, vno ret = 1; } else ret = 0; + if (cansleep != 0) + NFSUNLOCKSTATE(); FREE((caddr_t)stp, M_NFSDSTATE); newnfsstats.srvopens--; nfsrv_openpluslock--;
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