patacongo commented on pull request #2497:
URL: https://github.com/apache/incubator-nuttx/pull/2497#issuecomment-740768984
> We must therefore handle ECANCELED from nxsem_wait_uninterruptible()
ourselves instead of silently returning without any random bytes.
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.
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