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Avoid double-unlock or double unreference for ndp->ni_dvp when the vnode dp

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lock upgrade right after the 'success' label fails.

In collaboration with:	pho
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2012-01-01 18:45:59 +00:00
parent f8f33f6ab6
commit cdb7a43117
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=229185
1 changed files with 15 additions and 6 deletions
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21
sys/kern/vfs_lookup.c
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@ -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 @@ lookup(struct nameidata *ndp)
/*
* 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 @@ lookup(struct nameidata *ndp)
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 @@ lookup(struct nameidata *ndp)
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);