2.6.9: serial_core: uart_open

["karl malbrain" <karl@petzent.com>]

The uart_open code loops waiting for CD to be asserted (whenever CLOCAL 
is not set).  The bottom of the loop contains the following code:

up(&state->sem);
schedule();
down(&state->sem);

if( signal_pending(current) )
   break;

When I issue an open("/dev/ttyS1", O_RDWR) from a terminal session on 
the console, the system seems to come to a stop in this loop until the 
process is killed.  I suspect that the scheduler is choosing this process
to run again because of an elevated console priority of some sort.
 
Is there a kernel mechanism to put a process to sleep until awakened by 
an event to replace this looping behaviour?
 
Thanks, karl malbrain, malbrain-at-yahoo-dot-com



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