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| author | Mårten Nordheim <marten.nordheim@qt.io> | 2021-03-25 13:58:00 +0100 |
|---|---|---|
| committer | Mårten Nordheim <marten.nordheim@qt.io> | 2021-04-06 09:55:14 +0100 |
| commit | 9211d04730da7495fd2584e6768b73c3f86aba00 (patch) | |
| tree | d123064b77bc9ec4d9c0bbe8cb3e77e286fd24bd /src/corelib/thread | |
| parent | c87847db8781a6846069e0f7e55b8ccc64d9420d (diff) | |
QSemaphore: move suspect increment of waiter count
We might return false a few lines down, without decreasing the count.
Change-Id: I0a90c07f279860987e41539e9d5f3b5d2cb15207
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'src/corelib/thread')
| -rw-r--r-- | src/corelib/thread/qsemaphore.cpp | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/src/corelib/thread/qsemaphore.cpp b/src/corelib/thread/qsemaphore.cpp index ee4cee5281..5111d80ac6 100644 --- a/src/corelib/thread/qsemaphore.cpp +++ b/src/corelib/thread/qsemaphore.cpp @@ -246,13 +246,13 @@ template <bool IsTimed> bool futexSemaphoreTryAcquire(QBasicAtomicInteger<quintp // we need to wait quintptr oneWaiter = quintptr(Q_UINT64_C(1) << 32); // zero on 32-bit if (futexHasWaiterCount) { - // increase the waiter count - u.fetchAndAddRelaxed(oneWaiter); - // We don't use the fetched value from above so futexWait() fails if // it changed after the testAndSetOrdered above. if ((quint64(curValue) >> 32) == 0x7fffffff) return false; // overflow! + + // increase the waiter count + u.fetchAndAddRelaxed(oneWaiter); curValue += oneWaiter; // Also adjust nn to subtract oneWaiter when we succeed in acquiring. |