Module Name: src
Committed By: riastradh
Date: Fri Jul 28 10:38:44 UTC 2023
Modified Files:
src/sys/arch/xen/xen: xen_clock.c
Log Message:
xen_clock(4): Fix whitespace and sprinkle comments.
No functional change intended.
To generate a diff of this commit:
cvs rdiff -u -r1.12 -r1.13 src/sys/arch/xen/xen/xen_clock.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/xen_clock.c
diff -u src/sys/arch/xen/xen/xen_clock.c:1.12 src/sys/arch/xen/xen/xen_clock.c:1.13
--- src/sys/arch/xen/xen/xen_clock.c:1.12 Mon Jul 17 10:12:54 2023
+++ src/sys/arch/xen/xen/xen_clock.c Fri Jul 28 10:38:44 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: xen_clock.c,v 1.12 2023/07/17 10:12:54 bouyer Exp $ */
+/* $NetBSD: xen_clock.c,v 1.13 2023/07/28 10:38:44 riastradh Exp $ */
/*-
* Copyright (c) 2017, 2018 The NetBSD Foundation, Inc.
@@ -36,7 +36,7 @@
#endif
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xen_clock.c,v 1.12 2023/07/17 10:12:54 bouyer Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xen_clock.c,v 1.13 2023/07/28 10:38:44 riastradh Exp $");
#include <sys/param.h>
#include <sys/types.h>
@@ -673,11 +673,31 @@ xen_suspendclocks(struct cpu_info *ci)
KASSERT(ci == curcpu());
KASSERT(kpreempt_disabled());
+ /*
+ * Find the VIRQ_TIMER event channel and close it so new timer
+ * interrupt events stop getting delivered to it.
+ *
+ * XXX Should this happen later? This is not the reverse order
+ * of xen_resumeclocks. It is apparently necessary in this
+ * order only because we don't stash evtchn anywhere, but we
+ * could stash it.
+ */
evtch = unbind_virq_from_evtch(VIRQ_TIMER);
KASSERT(evtch != -1);
+ /*
+ * Mask the event channel so we stop getting new interrupts on
+ * it.
+ */
hypervisor_mask_event(evtch);
- event_remove_handler(evtch,
+
+ /*
+ * Now that we are no longer getting new interrupts, remove the
+ * handler and wait for any existing calls to the handler to
+ * complete. After this point, there can be no concurrent
+ * calls to xen_timer_handler.
+ */
+ event_remove_handler(evtch,
__FPTRCAST(int (*)(void *), xen_timer_handler), ci);
aprint_verbose("Xen clock: removed event channel %d\n", evtch);
@@ -705,9 +725,16 @@ xen_resumeclocks(struct cpu_info *ci)
KASSERT(ci == curcpu());
KASSERT(kpreempt_disabled());
+ /*
+ * Allocate an event channel to receive VIRQ_TIMER events.
+ */
evtch = bind_virq_to_evtch(VIRQ_TIMER);
KASSERT(evtch != -1);
+ /*
+ * Set an event handler for VIRQ_TIMER events to call
+ * xen_timer_handler.
+ */
snprintf(intr_xname, sizeof(intr_xname), "%s clock",
device_xname(ci->ci_dev));
/* XXX sketchy function pointer cast -- fix the API, please */
@@ -716,7 +743,6 @@ xen_resumeclocks(struct cpu_info *ci)
ci, IPL_CLOCK, NULL, intr_xname, true, ci) == NULL)
panic("failed to establish timer interrupt handler");
-
aprint_verbose("Xen %s: using event channel %d\n", intr_xname, evtch);
/* Disarm the periodic timer on Xen>=3.1 which is allegedly buggy. */
@@ -729,11 +755,15 @@ xen_resumeclocks(struct cpu_info *ci)
/* Pretend the last hardclock happened right now. */
ci->ci_xen_hardclock_systime_ns = xen_vcputime_systime_ns();
-
/* Arm the one-shot timer. */
error = HYPERVISOR_set_timer_op(ci->ci_xen_hardclock_systime_ns +
NS_PER_TICK);
KASSERT(error == 0);
+
+ /*
+ * Ready to go. Unmask the event. After this point, Xen may
+ * start calling xen_timer_handler.
+ */
hypervisor_unmask_event(evtch);
/* We'd better not have switched CPUs. */
