Date: Sun, 1 Jan 2012 18:45:59 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r229185 - head/sys/kern Message-ID: <201201011845.q01IjxQS025445@svn.freebsd.org>
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Author: kib Date: Sun Jan 1 18:45:59 2012 New Revision: 229185 URL: http://svn.freebsd.org/changeset/base/229185 Log: Avoid double-unlock or double unreference for ndp->ni_dvp when the vnode dp lock upgrade right after the 'success' label fails. In collaboration with: pho MFC after: 1 week Modified: head/sys/kern/vfs_lookup.c Modified: head/sys/kern/vfs_lookup.c ============================================================================== --- head/sys/kern/vfs_lookup.c Sun Jan 1 18:42:00 2012 (r229184) +++ head/sys/kern/vfs_lookup.c Sun Jan 1 18:45:59 2012 (r229185) @@ -508,12 +508,14 @@ lookup(struct nameidata *ndp) int dvfslocked; /* VFS Giant state for parent */ int tvfslocked; int lkflags_save; + int ni_dvp_unlocked; /* * Setup: break out flag bits into variables. */ dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; vfslocked = 0; + ni_dvp_unlocked = 0; ndp->ni_cnd.cn_flags &= ~GIANTHELD; wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, @@ -861,8 +863,10 @@ unionlookup: /* * Symlink code always expects an unlocked dvp. */ - if (ndp->ni_dvp != ndp->ni_vp) + if (ndp->ni_dvp != ndp->ni_vp) { VOP_UNLOCK(ndp->ni_dvp, 0); + ni_dvp_unlocked = 1; + } goto success; } @@ -909,14 +913,17 @@ nextname: VREF(ndp->ni_startdir); } if (!wantparent) { + ni_dvp_unlocked = 2; if (ndp->ni_dvp != dp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); VFS_UNLOCK_GIANT(dvfslocked); dvfslocked = 0; - } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) + } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) { VOP_UNLOCK(ndp->ni_dvp, 0); + ni_dvp_unlocked = 1; + } if (cnp->cn_flags & AUDITVNODE1) AUDIT_ARG_VNODE1(dp); @@ -945,10 +952,12 @@ success: return (0); bad2: - if (dp != ndp->ni_dvp) - vput(ndp->ni_dvp); - else - vrele(ndp->ni_dvp); + if (ni_dvp_unlocked != 2) { + if (dp != ndp->ni_dvp && !ni_dvp_unlocked) + vput(ndp->ni_dvp); + else + vrele(ndp->ni_dvp); + } bad: if (!dpunlocked) vput(dp);
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