[GitHub] [incubator-nuttx] patacongo commented on issue #2663: kthread_create hangs waiting on semaphore while trying to copy file descriptors

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patacongo commented on issue #2663:
URL: https://github.com/apache/incubator-nuttx/issues/2663#issuecomment-998443854


   > To me it seems kernel threads should have a different task group struct that excludes at least tg_filelist, tg_streamlist, tg_envsize, and tg_envp. Or at least these should not be initialized for kernel threads. The latter option would be easy, like the band-aid patch I already posted
   You are right.  There is no purpose in having most of those things in a kernel thread since they cannot have pthreads and, hence, can't really have a task group.  See Why Can't Kernel Threads Have pthreads? - NUTTX - Apache Software Foundation. 
   
   
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   There are other complications like:  What if a kernel thread creates a user task?  The inheritance of file descriptors, stdio I/O and the environment will get a lot more complex.
   
   The current design does save a lot of code duplication by re-using all of the user-space task structures.
   > It also seems that kernel threads should have their UID and GID set to 0 instead of inheriting it.
   Yes, but there is not fully developed user-based security in the OS so it would end up being mostly cosmetic.
   
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