From: mpi <mpi@openbsd.org>
Date: Sat, 8 Jul 2017 09:19:02 +0000 (+0000)
Subject: Revert grabbing the socket lock in kqueue filters.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=9da3575e51acd695cb33e5a319251ce88c518064;p=openbsd

Revert grabbing the socket lock in kqueue filters.

It is unsafe to sleep while iterating the list of pending events in
kqueue_scan().

Reported by abieber@ and juanfra@
---

diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index 7aa6aa595a4..8f686ee379a 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uipc_socket.c,v 1.192 2017/07/04 12:58:32 mpi Exp $	*/
+/*	$OpenBSD: uipc_socket.c,v 1.193 2017/07/08 09:19:02 mpi Exp $	*/
 /*	$NetBSD: uipc_socket.c,v 1.21 1996/02/04 02:17:52 christos Exp $	*/
 
 /*
@@ -1998,10 +1998,8 @@ int
 filt_sowrite(struct knote *kn, long hint)
 {
 	struct socket *so = kn->kn_fp->f_data;
-	int s, rv;
+	int rv;
 
-	if (!(hint & NOTE_SUBMIT))
-		s = solock(so);
 	kn->kn_data = sbspace(so, &so->so_snd);
 	if (so->so_state & SS_CANTSENDMORE) {
 		kn->kn_flags |= EV_EOF;
@@ -2017,8 +2015,6 @@ filt_sowrite(struct knote *kn, long hint)
 	} else {
 		rv = (kn->kn_data >= so->so_snd.sb_lowat);
 	}
-	if (!(hint & NOTE_SUBMIT))
-		sounlock(s);
 
 	return (rv);
 }
@@ -2027,13 +2023,8 @@ int
 filt_solisten(struct knote *kn, long hint)
 {
 	struct socket *so = kn->kn_fp->f_data;
-	int s;
 
-	if (!(hint & NOTE_SUBMIT))
-		s = solock(so);
 	kn->kn_data = so->so_qlen;
-	if (!(hint & NOTE_SUBMIT))
-		sounlock(s);
 
 	return (kn->kn_data != 0);
 }
diff --git a/sys/miscfs/fifofs/fifo_vnops.c b/sys/miscfs/fifofs/fifo_vnops.c
index cc6616ad23c..62b19a40fb0 100644
--- a/sys/miscfs/fifofs/fifo_vnops.c
+++ b/sys/miscfs/fifofs/fifo_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fifo_vnops.c,v 1.56 2017/07/03 08:31:39 mpi Exp $	*/
+/*	$OpenBSD: fifo_vnops.c,v 1.57 2017/07/08 09:19:02 mpi Exp $	*/
 /*	$NetBSD: fifo_vnops.c,v 1.18 1996/03/16 23:52:42 christos Exp $	*/
 
 /*
@@ -531,10 +531,8 @@ int
 filt_fiforead(struct knote *kn, long hint)
 {
 	struct socket *so = (struct socket *)kn->kn_hook;
-	int s, rv;
+	int rv;
 
-	if (!(hint & NOTE_SUBMIT))
-		s = solock(so);
 	kn->kn_data = so->so_rcv.sb_cc;
 	if (so->so_state & SS_CANTRCVMORE) {
 		kn->kn_flags |= EV_EOF;
@@ -543,8 +541,6 @@ filt_fiforead(struct knote *kn, long hint)
 		kn->kn_flags &= ~EV_EOF;
 		rv = (kn->kn_data > 0);
 	}
-	if (!(hint & NOTE_SUBMIT))
-		sounlock(s);
 
 	return (rv);
 }
@@ -563,10 +559,8 @@ int
 filt_fifowrite(struct knote *kn, long hint)
 {
 	struct socket *so = (struct socket *)kn->kn_hook;
-	int s, rv;
+	int rv;
 
-	if (!(hint & NOTE_SUBMIT))
-		s = solock(so);
 	kn->kn_data = sbspace(so, &so->so_snd);
 	if (so->so_state & SS_CANTSENDMORE) {
 		kn->kn_flags |= EV_EOF;
@@ -575,8 +569,6 @@ filt_fifowrite(struct knote *kn, long hint)
 		kn->kn_flags &= ~EV_EOF;
 		rv = (kn->kn_data >= so->so_snd.sb_lowat);
 	}
-	if (!(hint & NOTE_SUBMIT))
-		sounlock(s);
 
 	return (rv);
 }
diff --git a/sys/sys/socketvar.h b/sys/sys/socketvar.h
index c538b32625d..6289e48ab4e 100644
--- a/sys/sys/socketvar.h
+++ b/sys/sys/socketvar.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: socketvar.h,v 1.72 2017/07/04 12:58:32 mpi Exp $	*/
+/*	$OpenBSD: socketvar.h,v 1.73 2017/07/08 09:19:02 mpi Exp $	*/
 /*	$NetBSD: socketvar.h,v 1.18 1996/02/09 18:25:38 christos Exp $	*/
 
 /*-
@@ -186,7 +186,10 @@ static inline long
 sbspace(struct socket *so, struct sockbuf *sb)
 {
 	KASSERT(sb == &so->so_rcv || sb == &so->so_snd);
+#if 0
+	/* XXXSMP kqueue_scan() calling filt_sowrite() cannot sleep. */
 	soassertlocked(so);
+#endif
 	return lmin(sb->sb_hiwat - sb->sb_cc, sb->sb_mbmax - sb->sb_mbcnt);
 }