[src/trunk]: src/sys/net Use lock rather than 64-bit atomics for platforms wi...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c0abbc16cd85
branches:  trunk
changeset: 937568:c0abbc16cd85
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Fri Aug 21 20:21:36 2020 +0000

description:
Use lock rather than 64-bit atomics for platforms without the latter.

diffstat:

 sys/net/if_wg.c |  61 ++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 56 insertions(+), 5 deletions(-)

diffs (139 lines):

diff -r c99c108ab0c5 -r c0abbc16cd85 sys/net/if_wg.c
--- a/sys/net/if_wg.c   Fri Aug 21 20:16:39 2020 +0000
+++ b/sys/net/if_wg.c   Fri Aug 21 20:21:36 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_wg.c,v 1.21 2020/08/21 15:48:13 riastradh Exp $     */
+/*     $NetBSD: if_wg.c,v 1.22 2020/08/21 20:21:36 riastradh Exp $     */
 
 /*
  * Copyright (C) Ryota Ozaki <ozaki.ryota%gmail.com@localhost>
@@ -43,7 +43,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.21 2020/08/21 15:48:13 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.22 2020/08/21 20:21:36 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -457,8 +457,13 @@
 
        uint32_t        wgs_sender_index;
        uint32_t        wgs_receiver_index;
+#ifdef __HAVE_ATOMIC64_LOADSTORE
        volatile uint64_t
                        wgs_send_counter;
+#else
+       kmutex_t        wgs_send_counter_lock;
+       uint64_t        wgs_send_counter;
+#endif
 
        struct {
                kmutex_t        lock;
@@ -2031,6 +2036,38 @@
        WG_DUMP_HASH("wgs_tkey_recv", wgs->wgs_tkey_recv);
 }
 
+static uint64_t
+wg_session_get_send_counter(struct wg_session *wgs)
+{
+#ifdef __HAVE_ATOMIC64_LOADSTORE
+       return atomic_load_relaxed(&wgs->wgs_send_counter);
+#else
+       uint64_t send_counter;
+
+       mutex_enter(&wgs->wgs_send_counter_lock);
+       send_counter = wgs->wgs_send_counter;
+       mutex_exit(&wgs->wgs_send_counter_lock);
+
+       return send_counter;
+#endif
+}
+
+static uint64_t
+wg_session_inc_send_counter(struct wg_session *wgs)
+{
+#ifdef __HAVE_ATOMIC64_LOADSTORE
+       return atomic_inc_64_nv(&wgs->wgs_send_counter) - 1;
+#else
+       uint64_t send_counter;
+
+       mutex_enter(&wgs->wgs_send_counter_lock);
+       send_counter = wgs->wgs_send_counter++;
+       mutex_exit(&wgs->wgs_send_counter_lock);
+
+       return send_counter;
+#endif
+}
+
 static void
 wg_clear_states(struct wg_session *wgs)
 {
@@ -3010,7 +3047,8 @@
        if ((time_uptime - wgs->wgs_time_established) > wg_reject_after_time) {
                WG_DLOG("The session hits REJECT_AFTER_TIME\n");
                return true;
-       } else if (wgs->wgs_send_counter > wg_reject_after_messages) {
+       } else if (wg_session_get_send_counter(wgs) >
+           wg_reject_after_messages) {
                WG_DLOG("The session hits REJECT_AFTER_MESSAGES\n");
                return true;
        }
@@ -3155,6 +3193,9 @@
        wgs->wgs_state = WGS_STATE_UNKNOWN;
        psref_target_init(&wgs->wgs_psref, wg_psref_class);
        wgs->wgs_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
+#ifndef __HAVE_ATOMIC64_LOADSTORE
+       mutex_init(&wgs->wgs_send_counter_lock, MUTEX_DEFAULT, IPL_SOFTNET);
+#endif
        wgs->wgs_recvwin = kmem_zalloc(sizeof(*wgs->wgs_recvwin), KM_SLEEP);
        mutex_init(&wgs->wgs_recvwin->lock, MUTEX_DEFAULT, IPL_NONE);
 
@@ -3163,6 +3204,9 @@
        wgs->wgs_state = WGS_STATE_UNKNOWN;
        psref_target_init(&wgs->wgs_psref, wg_psref_class);
        wgs->wgs_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
+#ifndef __HAVE_ATOMIC64_LOADSTORE
+       mutex_init(&wgs->wgs_send_counter_lock, MUTEX_DEFAULT, IPL_SOFTNET);
+#endif
        wgs->wgs_recvwin = kmem_zalloc(sizeof(*wgs->wgs_recvwin), KM_SLEEP);
        mutex_init(&wgs->wgs_recvwin->lock, MUTEX_DEFAULT, IPL_NONE);
 
@@ -3203,12 +3247,18 @@
        mutex_obj_free(wgs->wgs_lock);
        mutex_destroy(&wgs->wgs_recvwin->lock);
        kmem_free(wgs->wgs_recvwin, sizeof(*wgs->wgs_recvwin));
+#ifndef __HAVE_ATOMIC64_LOADSTORE
+       mutex_destroy(&wgs->wgs_send_counter_lock);
+#endif
        kmem_free(wgs, sizeof(*wgs));
        wgs = wgp->wgp_session_stable;
        psref_target_destroy(&wgs->wgs_psref, wg_psref_class);
        mutex_obj_free(wgs->wgs_lock);
        mutex_destroy(&wgs->wgs_recvwin->lock);
        kmem_free(wgs->wgs_recvwin, sizeof(*wgs->wgs_recvwin));
+#ifndef __HAVE_ATOMIC64_LOADSTORE
+       mutex_destroy(&wgs->wgs_send_counter_lock);
+#endif
        kmem_free(wgs, sizeof(*wgs));
 
        psref_target_destroy(&wgp->wgp_endpoint->wgsa_psref, wg_psref_class);
@@ -3441,7 +3491,7 @@
        wgmd->wgmd_receiver = wgs->wgs_receiver_index;
        /* [W] 5.4.6: msg.counter := Nm^send */
        /* [W] 5.4.6: Nm^send := Nm^send + 1 */
-       wgmd->wgmd_counter = atomic_inc_64_nv(&wgs->wgs_send_counter) - 1;
+       wgmd->wgmd_counter = wg_session_inc_send_counter(wgs);
        WG_DLOG("counter=%"PRIu64"\n", wgmd->wgmd_counter);
 }
 
@@ -3629,7 +3679,8 @@
                        wg_schedule_rekey_timer(wgp);
                }
                wgs->wgs_time_last_data_sent = time_uptime;
-               if (wgs->wgs_send_counter >= wg_rekey_after_messages) {
+               if (wg_session_get_send_counter(wgs) >=
+                   wg_rekey_after_messages) {
                        /*
                         * [W] 6.2 Transport Message Limits
                         * "WireGuard will try to create a new session, by