FreeChainXenon/newlib-cygwin
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Cygwin: setjmp/longjmp: drop setting spinning flag

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Per the comment in _cygtls::interrupt_now(), the spinning flag
is supposed to guard that the targeted thread is about to enter
the Cygwin DLL.  Setting spinning has then been added to _sigfe,
_sigbe, sigdelayed and stabilize_sig_stack, the latter being called
from setjmp/longjmp.

However, setjmp/longjmp only enter the DLL in case of a pending
signal, calling _cygtls::call_signal_handler(). This in turn is
already guarded by setting the incyg flag, and there's no other
action in stabilize_sig_stack which might interfere with the
signal setup.  All the rest of setjmp/longjmp is plain userspace.

Therefore, drop setting the spinning flag from stabilize_sig_stack,
because it results in dropped signals in tight longjmp loops.

Fixes: edc4f86ad2 ("* Makefile.in (clean): Remove sigfe.s.")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2024-12-05 18:34:02 +01:00
parent 3a9fb7c561
commit 96d856320a
1 changed files with 0 additions and 1 deletions
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winsup/cygwin/scripts/gendef
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@ -332,7 +332,6 @@ stabilize_sig_stack:
movq %gs:8,%r12
1: movl \$1,%r10d
xchgl %r10d,_cygtls.stacklock(%r12) # try to acquire lock
movl %r10d,_cygtls.spinning(%r12) # flag if we are waiting for lock
testl %r10d,%r10d
jz 2f
pause