From f4b43aed417204659f08b66fd8bd4949227b3cb9 Mon Sep 17 00:00:00 2001
From: Taylor R Campbell <riastradh@NetBSD.org>
Date: Thu, 31 Mar 2022 02:42:27 +0000
Subject: [PATCH 40/49] ipi(9): Convert membar_exit/enter to
membar_release/acquire.
No store-before-load ordering needed here, just need to ensure that
in
A, ipi_send, ipi receive, B,
memory operations in A happen-before memory operations in B.
---
sys/kern/subr_ipi.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/sys/kern/subr_ipi.c b/sys/kern/subr_ipi.c
index 3d76d764a55c..1598df1cbf79 100644
--- a/sys/kern/subr_ipi.c
+++ b/sys/kern/subr_ipi.c
@@ -190,7 +190,7 @@ ipi_mark_pending(u_int ipi_id, struct cpu_info *ci)
/* Mark as pending and return true if not previously marked. */
if ((atomic_load_acquire(&ci->ci_ipipend[i]) & bitm) == 0) {
#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_exit();
+ membar_release();
#endif
atomic_or_32(&ci->ci_ipipend[i], bitm);
return true;
@@ -265,7 +265,7 @@ ipi_trigger_broadcast(u_int ipi_id, bool skip_self)
/*
* put_msg: insert message into the mailbox.
*
- * Caller is responsible for issuing membar_exit first.
+ * Caller is responsible for issuing membar_release first.
*/
static inline void
put_msg(ipi_mbox_t *mbox, ipi_msg_t *msg)
@@ -304,7 +304,7 @@ ipi_cpu_handler(void)
}
pending = atomic_swap_32(&ci->ci_ipipend[i], 0);
#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_enter();
+ membar_acquire();
#endif
while ((bit = ffs(pending)) != 0) {
const u_int ipi_id = (i << IPI_BITW_SHIFT) | --bit;
@@ -342,7 +342,7 @@ ipi_msg_cpu_handler(void *arg __unused)
/* Ack the request. */
#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_exit();
+ membar_release();
#endif
atomic_dec_uint(&msg->_pending);
}
@@ -365,7 +365,7 @@ ipi_unicast(ipi_msg_t *msg, struct cpu_info *ci)
msg->_pending = 1;
#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_exit();
+ membar_release();
#endif
put_msg(&ipi_mboxes[id], msg);
@@ -391,7 +391,7 @@ ipi_multicast(ipi_msg_t *msg, const kcpuset_t *target)
local = !!kcpuset_isset(target, cpu_index(self));
msg->_pending = kcpuset_countset(target) - local;
#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_exit();
+ membar_release();
#endif
for (CPU_INFO_FOREACH(cii, ci)) {
@@ -429,7 +429,7 @@ ipi_broadcast(ipi_msg_t *msg, bool skip_self)
msg->_pending = ncpu - 1;
#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_exit();
+ membar_release();
#endif
/* Broadcast IPIs for remote CPUs. */