Date: Wed, 3 Aug 2011 14:29:20 +0000 (UTC) From: Konstantin Belousov <kib@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: r224635 - stable/8/sys/fs/devfs Message-ID: <201108031429.p73ETK2X017231@svn.freebsd.org>
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Author: kib Date: Wed Aug 3 14:29:20 2011 New Revision: 224635 URL: http://svn.freebsd.org/changeset/base/224635 Log: MFC r223988: While fixing the looping of a thread while devfs vnode is reclaimed, r179247 introduced a possibility of devfs_allocv() returning spurious ENOENT. If the vnode is selected by vnlru daemon for reclamation, then devfs_allocv() can get ENOENT from vget() due to devfs_close() dropping vnode lock around the call to cdevsw d_close method. Use LK_RETRY in the vget() call, and do some part of the devfs_reclaim() work in devfs_allocv(), clearing vp->v_data and de->de_vnode. Retry the allocation of the vnode, now with de->de_vnode == NULL. The check vp->v_data == NULL at the start of devfs_close() cannot be affected by the change, since vnode lock must be held while VI_DOOMED is set, and only dropped after the check. Modified: stable/8/sys/fs/devfs/devfs_vnops.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) Modified: stable/8/sys/fs/devfs/devfs_vnops.c ============================================================================== --- stable/8/sys/fs/devfs/devfs_vnops.c Wed Aug 3 13:39:11 2011 (r224634) +++ stable/8/sys/fs/devfs/devfs_vnops.c Wed Aug 3 14:29:20 2011 (r224635) @@ -346,6 +346,7 @@ devfs_allocv(struct devfs_dirent *de, st sx_xunlock(&dmp->dm_lock); return (ENOENT); } +loop: DEVFS_DE_HOLD(de); DEVFS_DMP_HOLD(dmp); mtx_lock(&devfs_de_interlock); @@ -354,16 +355,21 @@ devfs_allocv(struct devfs_dirent *de, st VI_LOCK(vp); mtx_unlock(&devfs_de_interlock); sx_xunlock(&dmp->dm_lock); - error = vget(vp, lockmode | LK_INTERLOCK, curthread); + vget(vp, lockmode | LK_INTERLOCK | LK_RETRY, curthread); sx_xlock(&dmp->dm_lock); if (devfs_allocv_drop_refs(0, dmp, de)) { - if (error == 0) - vput(vp); + vput(vp); return (ENOENT); } - else if (error) { - sx_xunlock(&dmp->dm_lock); - return (error); + else if ((vp->v_iflag & VI_DOOMED) != 0) { + mtx_lock(&devfs_de_interlock); + if (de->de_vnode == vp) { + de->de_vnode = NULL; + vp->v_data = NULL; + } + mtx_unlock(&devfs_de_interlock); + vput(vp); + goto loop; } sx_xunlock(&dmp->dm_lock); *vpp = vp;
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