Author: kib
Date: Thu May 21 11:12:27 2020
New Revision: 361327
URL: https://svnweb.freebsd.org/changeset/base/361327
Log:
MFC r361037, r361056:
Fix spurious ENOTCONN from closed unix domain socket other' side.
Modified:
stable/12/sys/kern/uipc_socket.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/kern/uipc_socket.c
==============================================================================
--- stable/12/sys/kern/uipc_socket.c Thu May 21 06:40:51 2020
(r361326)
+++ stable/12/sys/kern/uipc_socket.c Thu May 21 11:12:27 2020
(r361327)
@@ -1792,8 +1792,9 @@ restart:
m = so->so_rcv.sb_mb;
goto dontblock;
}
- if ((so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING)) == 0 &&
- (so->so_proto->pr_flags & PR_CONNREQUIRED)) {
+ if ((so->so_state & (SS_ISCONNECTING | SS_ISCONNECTED |
+ SS_ISDISCONNECTING | SS_ISDISCONNECTED)) == 0 &&
+ (so->so_proto->pr_flags & PR_CONNREQUIRED) != 0) {
SOCKBUF_UNLOCK(&so->so_rcv);
error = ENOTCONN;
goto release;
@@ -3814,8 +3815,17 @@ soisdisconnected(struct socket *so)
{
SOCK_LOCK(so);
- so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
+
+ /*
+ * There is at least one reader of so_state that does not
+ * acquire socket lock, namely soreceive_generic(). Ensure
+ * that it never sees all flags that track connection status
+ * cleared, by ordering the update with a barrier semantic of
+ * our release thread fence.
+ */
so->so_state |= SS_ISDISCONNECTED;
+ atomic_thread_fence_rel();
+ so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
if (!SOLISTENING(so)) {
SOCK_UNLOCK(so);
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