Re: [Qemu-devel] [PATCH v3] monitor: let cur_mon be per-thread

[Eric Blake]

On 04/12/2018 01:11 AM, Peter Xu wrote:
> In the future the monitor iothread may be accessing the cur_mon as
> well (via monitor_qmp_dispatch_one()).  Before we introduce a real
> Out-Of-Band command, let's convert the cur_mon variable to be a
> per-thread variable to make sure there won't be a race between threads.
> 
> Note that thread variables are not initialized to a valid value when new
> thread is created.  However for our case we don't need to set it up,
> since the cur_mon variable is only used in such a pattern:
> 
>   old_mon = cur_mon;
>   cur_mon = xxx;
>   (do something, read cur_mon if necessary in the stack)
>   cur_mon = old_mon;
> 
> It plays a role as stack variable, so no need to be initialized at all.
> We only need to make sure the variable won't be changed unexpectedly by
> other threads.
> 
> Signed-off-by: Peter Xu <address@hidden>
> ---

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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