From: Vitaliy Makkoveev <mvs@openbsd.org>
Subject: filt_sow{modify,process}(): don't take netlock
To: Alexander Bluhm <bluhm@openbsd.org>, tech@openbsd.org
Date: Fri, 31 Jan 2025 17:17:04 +0300

The `sb_mtx' mutex(9) is enough to call filt_sowrite(). The same is also
true for filt_soexcept(), but I want to do this separately because
filt_soexcept() shares filt_sormodify() and filt_sorprocess() with
filt_soread().

Index: sys/kern/uipc_socket.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_socket.c,v
diff -u -p -r1.367 uipc_socket.c
--- sys/kern/uipc_socket.c	30 Jan 2025 14:40:50 -0000	1.367
+++ sys/kern/uipc_socket.c	31 Jan 2025 14:09:19 -0000
@@ -2482,9 +2482,9 @@ filt_sowmodify(struct kevent *kev, struc
 	struct socket *so = kn->kn_fp->f_data;
 	int rv;
 
-	sofilt_lock(so, &so->so_snd);
+	mtx_enter(&so->so_snd.sb_mtx);
 	rv = knote_modify(kev, kn);
-	sofilt_unlock(so, &so->so_snd);
+	mtx_leave(&so->so_snd.sb_mtx);
 
 	return (rv);
 }
@@ -2495,9 +2495,9 @@ filt_sowprocess(struct knote *kn, struct
 	struct socket *so = kn->kn_fp->f_data;
 	int rv;
 
-	sofilt_lock(so, &so->so_snd);
+	mtx_enter(&so->so_snd.sb_mtx);
 	rv = knote_process(kn, kev);
-	sofilt_unlock(so, &so->so_snd);
+	mtx_leave(&so->so_snd.sb_mtx);
 
 	return (rv);
 }