[RFC][BZ #19329] high level description of pthread_create vs dlopen races

[Joseph Myers]

On Tue, 6 Dec 2016, Szabolcs Nagy wrote:

> meanwhile the rest of the world needs a way to detect
> reentry into an as-safe library call which currently
> requires as-safe tls (signal mask is not an option:
> syscalls are too slow) and a way to do soft float
> correctly (fenv is tls and arithmetics must be as-safe)
> or just access errno (which could be made as-safe even
> if tls access is not as-safe otherwise, but specifying
> that correctly in the standard is more hassle than
> requiring all tls access to be as-safe).

errno, the powerpc soft-float floating-point environment and the libdfp 
soft-dfp decimal rounding mode are all initial-exec TLS (and other cases 
of floating-point environment are hardware registers rather than TLS 
variables).  Does being initial-exec help?

-- 
Joseph S. Myers
joseph@codesourcery.com