[PATCH v2] Cygwin: signal: Do not handle signal when __SIGFLUSHFAST is sent

[Jeremy Drake]

On Sat, 18 Jan 2025, Takashi Yano wrote:

> While debugging this problem, I encountered another hang issue,
> which is fixed by:
> 0001-Cygwin-signal-Avoid-frequent-tls-lock-unlock-for-SIG.patch

I'm concerned about this patch.  There's a window where current_sig could
be changed after exiting the while, before the lock is acquired by
cygheap->find_tls (_main_tls);  Should current_sig be rechecked after the
lock is acquired to make sure that hasn't happened?  Also, does
current_sig need to be volatile, or is yield a sufficient fence for the
compiler to know other threads may have changed the value?