Date: Wed, 21 May 2014 03:11:27 +0000 (UTC) From: Benjamin Kaduk <bjk@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r266482 - head/sys/kern Message-ID: <201405210311.s4L3BROu047001@svn.freebsd.org>
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Author: bjk (doc committer) Date: Wed May 21 03:11:27 2014 New Revision: 266482 URL: http://svnweb.freebsd.org/changeset/base/266482 Log: Check for mismatched vref()/vdrop() Assert that the hold count has not fallen below the use count, a situation that would only happen when a vref() (or similar) is erroneously paired with a vdrop(). This situation has not been observed in the wild, but could be helpful for someone implementing a new filesystem. Reviewed by: kib Approved by: hrs (mentor) Modified: head/sys/kern/vfs_subr.c Modified: head/sys/kern/vfs_subr.c ============================================================================== --- head/sys/kern/vfs_subr.c Tue May 20 22:43:17 2014 (r266481) +++ head/sys/kern/vfs_subr.c Wed May 21 03:11:27 2014 (r266482) @@ -2343,6 +2343,8 @@ vdropl(struct vnode *vp) if (vp->v_holdcnt <= 0) panic("vdrop: holdcnt %d", vp->v_holdcnt); vp->v_holdcnt--; + VNASSERT(vp->v_holdcnt >= vp->v_usecount, vp, + ("hold count less than use count")); if (vp->v_holdcnt > 0) { VI_UNLOCK(vp); return;
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