ugen(4) and poll(2)

Thu Apr 24 16:57:02 PDT 2008

Hasso Tepper wrote:
As far as I can see what happens is that daemon opens ugen(4) device 
correctly and starts to poll(2) interrupt endpoint of the device (devices 
have single interface). The trouble is that poll(2) seems to ignore 
timeout. It doesn't return until there is data available in the 
descriptor. Ie I can make poll(2) to return with poking device, but till 
then it blocks.

Before I dig deep into areas I'm not familiar with ... Any ideas why and 
where it might happen? Anyone seen something like this?
In which waitchan is the process?  If it is in "poll" and you're really 
passing a proper timeout value, then everything should work as advertised. 
 Does a ktrace show only the poll and no return?  Sometimes processes 
tend to re-call poll over and over again (maybe due to an interrupting 
signal).

cheers
  simon
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