Re: [Qemu-devel] [PATCH v4 2/3] Extract code to nbd_setup function to be used for many purposes

[Paolo Bonzini <pbonzini@redhat.com>]

On 12/06/2011 07:56 AM, Chunyan Liu wrote:
>
> Currently, the nbd_setup needs parameters: device, srcpath, flags,
> partition, dev_offset, nbdflags, sockpath, bindto, port, shared,
> persistent, verbose, sigterm_rfd. More than 10 parameters. I still
> didn't find a better way to reduce parameters. Making variables global
> is a workaround to avoid nbd_setup taking too many parameters. Actually,
> except for sigterm_rfd, all others are pared from command line options.

Reading again this patch, I am not sure why you are doing it this way.

There is no reason why bdrv_new/open/delete has to be redone for every 
/dev/nbdX we try (or if there is a reason, _that_ is what should be 
fixed first).  Also the "tail" of nbd_setup, basically the select loop, 
should not be tried multiple times.

I do not understand why you cannot simply do it like this:

- in the server thread, do everything as it is now

- pass "device" to the client thread instead of opening it in main()

- in the client thread, either use "device" as it is or (if device == 
NULL, which implies find == 1) loop until nbd_init succeeds.

Am I just confused?

Paolo