[mythtv-users] SUID root might hang your myth box

[Michael J. Lynch]

As root user do:

chmod a-s /usr/bin/mythfrontend


Brad Fuller wrote:

>
>
> Phil Blundell wrote:
>
>>on Thu, Nov 18, 2004 at 01:48:40AM -0800, Joe Barnhart wrote:
>>  
>>
>>>Why does this seemingly innocuous setting cause such a
>>>huge problem?  Why is it recommended?  Does the
>>>benefit outweigh the stress on my box turning it off
>>>and on a bunch of times trying to get the setting to
>>>work?
>>>    
>>>
>>
>>Making mythfrontsend setuid root allows it to set the video playback
>>thread to "realtime" priority, which means it will always have
>>precedence over any other task on the system.  This avoids any
>>stuttering that might be caused if the playback thread is delayed for
>>too long by other processes, which is why it's normally desirable.
>>
>>But, as you've discovered, if mythfrontend crashes in such a way that
>>the playback thread is stuck in a tight loop, it will consume all the
>>CPU time and no other task will ever be allowed to run.  Since this
>>includes ssh and the shell, there is no way to kill the errant thread.
>>The only way to regain control is to reset the machine.
>>
>>If you aren't experiencing any video playback problems, there is no
>>benefit in making the executable setuid.  On the other hand, if Myth is
>>working correctly, there should be no harm in making it setuid either.
>>  
>>
> How would one change it back?
>
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-- 
Michael J. Lynch

What if the hokey pokey IS what it's all about -- author unknown