https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=7c8e7f92e3ce85de1fe966ad9bba8307df796e94
commit 7c8e7f92e3ce85de1fe966ad9bba8307df796e94
Author: Corinna Vinschen <cori...@vinschen.de>
AuthorDate: Wed Jul 16 11:26:15 2025 +0200
Commit: Corinna Vinschen <cori...@vinschen.de>
CommitDate: Wed Jul 16 12:16:57 2025 +0200
Cygwin: clocks: use InterlockedCompareExchange64
The clock init functions checked timer ticks/period for 0 and then
called InterlockedExchange64 if the value was still 0. This is not
quite as atomic as it was supposed to be.
Use InterlockedCompareExchange64 instead.
Fixes: 2b72887ac834b ("Cygwin: clocks: fix a hang on pre-Windows 10
machines")
Signed-off-by: Corinna Vinschen <cori...@vinschen.de>
(cherry picked from commit 167ace9a6d9605f67cd52369dd1e7758ec0d0af5)
Diff:
---
winsup/cygwin/clock.cc | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/winsup/cygwin/clock.cc b/winsup/cygwin/clock.cc
index 2a4e86922b4a..dc940906edb0 100644
--- a/winsup/cygwin/clock.cc
+++ b/winsup/cygwin/clock.cc
@@ -32,22 +32,19 @@ system_tickcount_period ()
void inline
clk_t::init ()
{
- if (!period)
- InterlockedExchange64 (&period, system_tickcount_period ());
+ InterlockedCompareExchange64 (&period, system_tickcount_period (), 0);
}
void inline
clk_realtime_t::init ()
{
- if (!ticks_per_sec)
- InterlockedExchange64 (&ticks_per_sec, system_qpc_tickspersec ());
+ InterlockedCompareExchange64 (&ticks_per_sec, system_qpc_tickspersec (), 0);
}
void inline
clk_monotonic_t::init ()
{
- if (!ticks_per_sec)
- InterlockedExchange64 (&ticks_per_sec, system_qpc_tickspersec ());
+ InterlockedCompareExchange64 (&ticks_per_sec, system_qpc_tickspersec (), 0);
}
int
