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When detaching an unix domain socket, uipc_detach() checks

Browse Source 
unp->unp_vnode pointer to detect if there is a vnode associated with
(binded to) this socket and does necessary cleanup if there is.

The issue is that after forced unmount this check may be too late as
the unp_vnode is reclaimed and the reference is stale.

To fix this provide a helper function that is called on a socket vnode
reclamation to do necessary cleanup.

Pointed by:	kib
Reviewed by:	kib
MFC after:	2 weeks
This commit is contained in:
trociny 2012-02-25 10:15:41 +00:00
parent 1227707e55
commit 87f7f0cfe8
3 changed files with 43 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
sys/kern/uipc_usrreq.c
View File

@ -2300,6 +2300,45 @@ unp_scan(struct mbuf *m0, void (*op)(struct file *))
}
}
/*
* A helper function called by VFS before socket-type vnode reclamation.
* For an active vnode it clears unp_vnode pointer and decrements unp_vnode
* use count.
*/
void
vfs_unp_reclaim(struct vnode *vp)
{
struct socket *so;
struct unpcb *unp;
int active;
ASSERT_VOP_ELOCKED(vp, "vfs_unp_reclaim");
KASSERT(vp->v_type == VSOCK,
("vfs_unp_reclaim: vp->v_type != VSOCK"));
active = 0;
UNP_LINK_WLOCK();
so = vp->v_socket;
if (so == NULL)
goto done;
unp = sotounpcb(so);
if (unp == NULL)
goto done;
UNP_PCB_LOCK(unp);
if (unp->unp_vnode != NULL) {
KASSERT(unp->unp_vnode == vp,
("vfs_unp_reclaim: vp != unp->unp_vnode"));
vp->v_socket = NULL;
unp->unp_vnode = NULL;
active = 1;
}
UNP_PCB_UNLOCK(unp);
done:
UNP_LINK_WUNLOCK();
if (active)
vunref(vp);
}
#ifdef DDB
static void
db_print_indent(int indent)

2
sys/kern/vfs_subr.c
View File

@ -2657,6 +2657,8 @@ vgonel(struct vnode *vp)
vinactive(vp, td);
VI_UNLOCK(vp);
}
if (vp->v_type == VSOCK)
vfs_unp_reclaim(vp);
/*
* Reclaim the vnode.
*/

2
sys/sys/vnode.h
View File

@ -793,6 +793,8 @@ int vfs_read_dirent(struct vop_readdir_args *ap, struct dirent *dp, off_t off);
int vfs_unixify_accmode(accmode_t *accmode);
void vfs_unp_reclaim(struct vnode *vp);
int setfmode(struct thread *td, struct ucred *cred, struct vnode *vp, int mode);
int setfown(struct thread *td, struct ucred *cred, struct vnode *vp, uid_t uid,
gid_t gid);