Fixed a issue where same client requested multiple times

[saifuddin-xilinx]

Problem solved by the commit

-- There is a issue where same client requested the XRT driver multiple time.
-- In our XRT driver we haven't any check before creating a client or destroying a client.
-- In this PR I have added such checks based on the PID. If same PID is requested then it just increase a reference count and return, While deleting if the reference count is "0" then only it will cleanup that client.

Bug / issue (if any) fixed, which PR introduced the bug, how it was discovered

How problem was solved, alternative solutions (if any) and why they were rejected

Risks (if any) associated the changes in the commit

What has been tested and how, request additional testing if necessary

Documentation impact (if any)

[gbuildx]

Build failed :(

[gbuildx]

Build failed :(

[saifuddin-xilinx]

retest this please

[gbuildx]

Build failed :(

[saifuddin-xilinx]

retest this please

[gbuildx]

Build failed :(

[maxzhen]

Conceptually, a client is mapped to a fd. Now after this change, multiple fd from same process will share the same client. What does not work before?

Is this change valid for other parts of XRT...Say, if a cu context is opened through one fd, it is considered as "opened" by any fd in that process?

[saifuddin-xilinx]

Conceptually, a client is mapped to a fd. Now after this change, multiple fd from same process will share the same client. What does not work before?

Is this change valid for other parts of XRT...Say, if a cu context is opened through one fd, it is considered as "opened" by any fd in that process?

Thanks for the feedback. I am checking with vvas team for the application.

[saifuddin-xilinx]

No longer required. Application has to take care of opening multiple clients.