[servers/console] Fix reentrancy issues #124
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There were a few: - The `handle_connection` method would save away the mailbox IDs for its connection to the video server (VGA), for later use. It would then sit and _block on receive_ on the input mailbox from it, effectively blocking other threads from using it. A typical reentrancy bug. - The code for opening up new consoles would call `video_mode_set()`, using the above data structure, but if multiple consoles were being opened simultaneously (which happen now since we run servers in parallel at boot), the same thing could happen - multiple threads tried to use a single connection to the VGA server, which works very poorly. I added a poor man's semaphore to work around this.
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There were a few:
handle_connectionmethod would save away the mailbox IDs forits connection to the video server (VGA), for later use. It would then
sit and block on receive on the input mailbox from it, effectively
blocking other threads from using it. A typical reentrancy bug.
video_mode_set(),using the above data structure, but if multiple consoles were being
opened simultaneously (which happen now since we run servers in parallel
at boot), the same thing could happen - multiple threads tried to use a
single connection to the VGA server, which works very poorly. I added a
poor man's semaphore to work around this.