Re: [Qemu-devel] [PATCH v5 3/4] monitor: more comments on lock-free fleids/funcs

[Markus Armbruster]

Peter Xu <address@hidden> writes:

> Add some explicit comment for both Readline and cpu_set/cpu_get helpers
> that they do not need the mon_lock protection.

Appreciated!

> Signed-off-by: Peter Xu <address@hidden>
> ---
>  monitor.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index d6c3c08932..ae5bca9d7c 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -207,7 +207,7 @@ struct Monitor {
>      int suspend_cnt;            /* Needs to be accessed atomically */
>      bool skip_flush;
>      bool use_io_thr;
> -    ReadLineState *rs;
> +    ReadLineState *rs;   /* Only used in parser, so no lock needed. */

Pardon the ignorant question: why does "only used in parser" imply "no
lock needed"?

>      MonitorQMP qmp;
>      gchar *mon_cpu_path;
>      BlockCompletionFunc *password_completion_cb;
> @@ -1313,7 +1313,7 @@ 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.  BQL needed. */

It's okay to start a comment containing a phrase with a lower case
letter, but you're turning this one into two sentences, and sentences
start in upper case.  Can touch up on commit.

"BQL needed" is okay, just a bit terse; I'd write "Caller must hold
BQL".  Could change that, too.

>  int monitor_set_cpu(int cpu_index)
>  {
>      CPUState *cpu;
> @@ -1327,6 +1327,7 @@ int monitor_set_cpu(int cpu_index)
>      return 0;
>  }
>  
> +/* BQL neeeded. */

Likewise.

>  static CPUState *mon_get_cpu_sync(bool synchronize)
>  {
>      CPUState *cpu;