diff mbox series

[v8,3/5] monitor: more comments on lock-free elements

Message ID 20180528071958.17053-4-peterx@redhat.com
State New
Headers show
Series monitor: let Monitor be thread safe | expand

Commit Message

Peter Xu May 28, 2018, 7:19 a.m. UTC 
Add some explicit comments for both Readline and cpu_set/cpu_get helpers
that they do not need the mon_lock protection.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 monitor.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/monitor.c b/monitor.c
index d6c3c08932..f23178951e 100644
--- a/monitor.c
+++ b/monitor.c
@@ -207,7 +207,15 @@  struct Monitor {
     int suspend_cnt;            /* Needs to be accessed atomically */
     bool skip_flush;
     bool use_io_thr;
+
+    /*
+     * State used only in the thread "owning" the monitor.
+     * If @use_io_thr, this is mon_global.mon_iothread.
+     * Else, it's the main thread.
+     * These members can be safely accessed without locks.
+     */
     ReadLineState *rs;
+
     MonitorQMP qmp;
     gchar *mon_cpu_path;
     BlockCompletionFunc *password_completion_cb;
@@ -1313,7 +1321,7 @@  void qmp_qmp_capabilities(bool has_enable, QMPCapabilityList *enable,
     cur_mon->qmp.commands = &qmp_commands;
 }
 
-/* set the current CPU defined by the user */
+/* Set the current CPU defined by the user. Callers must hold BQL. */
 int monitor_set_cpu(int cpu_index)
 {
     CPUState *cpu;
@@ -1327,6 +1335,7 @@  int monitor_set_cpu(int cpu_index)
     return 0;
 }
 
+/* Callers must hold BQL. */
 static CPUState *mon_get_cpu_sync(bool synchronize)
 {
     CPUState *cpu;