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unp_detach(): unlock socket only if vput() required
At this time `unp_gc_lock' rwlock(9) could be taken after solock() as
it is done in uipc_attach(). The only reason to unlock dying `so' is
lock order with vnode(9) lock `i_lock' required to release `unp_vnode'.
So push re-lock to vnode(9) release path instead doing this every time.
Index: sys/kern/uipc_usrreq.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_usrreq.c,v
diff -u -p -r1.206 uipc_usrreq.c
--- sys/kern/uipc_usrreq.c 3 May 2024 17:43:09 -0000 1.206
+++ sys/kern/uipc_usrreq.c 20 Jun 2024 18:12:44 -0000
@@ -761,25 +761,21 @@ unp_detach(struct unpcb *unp)
unp->unp_vnode = NULL;
- /*
- * Enforce `i_lock' -> `solock()' lock order.
- */
- sounlock(so);
-
rw_enter_write(&unp_gc_lock);
LIST_REMOVE(unp, unp_link);
rw_exit_write(&unp_gc_lock);
if (vp != NULL) {
+ /* Enforce `i_lock' -> solock() lock order. */
+ sounlock(so);
VOP_LOCK(vp, LK_EXCLUSIVE);
vp->v_socket = NULL;
KERNEL_LOCK();
vput(vp);
KERNEL_UNLOCK();
+ solock(so);
}
-
- solock(so);
if (unp->unp_conn != NULL) {
/*
unp_detach(): unlock socket only if vput() required