Module Name: src
Committed By: riastradh
Date: Sat Feb 25 00:33:27 UTC 2023
Modified Files:
src/sys/arch/xen/xen: xencons.c
Log Message:
xencons(4): Membar audit.
- xenconscn_getc: Once we have consumed an input slot, it is clearer
to issue xen_wmb (release, i.e., load/store-before-store) before
advancing in_cons so that the update becomes a store-release
freeing the input slot for the other side to reuse.
- xenconscn_putc: After filling an output slot, must issue xen_wmb
(release, i.e., load/store-before-store) before advancing out_prod,
and another one before notifying the other side of the advance.
To generate a diff of this commit:
cvs rdiff -u -r1.50 -r1.51 src/sys/arch/xen/xen/xencons.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/xen/xen/xencons.c
diff -u src/sys/arch/xen/xen/xencons.c:1.50 src/sys/arch/xen/xen/xencons.c:1.51
--- src/sys/arch/xen/xen/xencons.c:1.50 Thu May 7 19:25:57 2020
+++ src/sys/arch/xen/xen/xencons.c Sat Feb 25 00:33:27 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: xencons.c,v 1.50 2020/05/07 19:25:57 maxv Exp $ */
+/* $NetBSD: xencons.c,v 1.51 2023/02/25 00:33:27 riastradh Exp $ */
/*
* Copyright (c) 2006 Manuel Bouyer.
@@ -53,7 +53,7 @@
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xencons.c,v 1.50 2020/05/07 19:25:57 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xencons.c,v 1.51 2023/02/25 00:33:27 riastradh Exp $");
#include "opt_xen.h"
@@ -583,7 +583,7 @@ xenconscn_getc(dev_t dev)
xen_rmb();
c = xencons_interface->in[MASK_XENCONS_IDX(xencons_interface->in_cons,
xencons_interface->in)];
- xen_rmb();
+ xen_wmb();
xencons_interface->in_cons = cons + 1;
cn_check_magic(dev, c, xencons_cnm_state);
splx(s);
@@ -614,9 +614,9 @@ xenconscn_putc(dev_t dev, int c)
}
xencons_interface->out[MASK_XENCONS_IDX(xencons_interface->out_prod,
xencons_interface->out)] = c;
- xen_rmb();
+ xen_wmb();
xencons_interface->out_prod++;
- xen_rmb();
+ xen_wmb();
hypervisor_notify_via_evtchn(xen_start_info.console.domU.evtchn);
splx(s);
}
