patacongo edited a comment on pull request #2488:
URL: https://github.com/apache/incubator-nuttx/pull/2488#issuecomment-740772533


   > But now you directly ignore the error at all, could you tell me how can 
the caller handle these error case securely?
   > 
   >     1. nxsem_wait_uninterruptible return fail
   >    ...
   
   From #2497 
   
   getrandom() is not a cancellation point and must not implement any 
cancellation point logic. It should not use nxsem_wait_uninterruptible() but 
should use something like nxsem_wait_noncancelable(). 
nxsem_wait-noncancelable() has not been formalized but would simply ignore the 
ECANCELED error (as well as the EINTR error).
   
   In that case, getrandom would correctly ignore the cancellation request and 
simply call nxsem_wait() again.
   
   ECANCELED should only occur in the deferred cancellation mode. In other 
modes, the task calling getrandom() will be terminated immediately with no 
return value. (I think anyway. I haven't looked at the code in a long time). In 
the deferred cancellation mode, cancellation can only occur at a few 
cancellation points; getrandom() is not a cancellatoin point.
   
   In normal usage, ECANCELED is never seen by the application code.  It is 
either not generated or is handled by the lower level cancellation point (which 
getrandom() is not).  Hence, there is no need to return the ECANCELED error 
code.
   
   
   


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