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Fix return type of _q_futex()

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syscall(2) returns long, not int. Says Clang:

  qfutex_linux_p.h:48:18: error:
    implicit conversion loses integer precision: 'long' to 'int'
    [-Werror,-Wshorten-64-to-32]

        int result = syscall(__NR_futex, addr, op | FUTEX_PRIVATE_FLAG, val, val2, addr2, val3);
            ~~~~~~   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Don't truncate to int in _q_futex(), pass it as long into the few
callers that care about the result.

Amends the start of the public history, but not picking back all the
way because the code moved around a lot. In 6.7 it found its current
place.

Pick-to: 6.8 6.7
Task-number: QTBUG-103528
Task-number: QTBUG-126219
Change-Id: I54ccaf5564bcaf38f05fab153b1b32379a66a178
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Marc Mutz 2024-06-11 11:52:57 +02:00
parent 22761f13d3
commit 962539d12b
1 changed files with 5 additions and 5 deletions
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10
src/corelib/thread/qfutex_linux_p.h
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@ -38,14 +38,14 @@ QT_BEGIN_NAMESPACE
namespace QtLinuxFutex {
constexpr inline bool futexAvailable() { return true; }
inline int _q_futex(int *addr, int op, int val, quintptr val2 = 0,
int *addr2 = nullptr, int val3 = 0) noexcept
inline long _q_futex(int *addr, int op, int val, quintptr val2 = 0,
int *addr2 = nullptr, int val3 = 0) noexcept
{
QtTsan::futexRelease(addr, addr2);
// we use __NR_futex because some libcs (like Android's bionic) don't
// provide SYS_futex etc.
int result = syscall(__NR_futex, addr, op | FUTEX_PRIVATE_FLAG, val, val2, addr2, val3);
long result = syscall(__NR_futex, addr, op | FUTEX_PRIVATE_FLAG, val, val2, addr2, val3);
QtTsan::futexAcquire(addr, addr2);
@ -71,8 +71,8 @@ inline bool futexWait(Atomic &futex, typename Atomic::Type expectedValue, QDeadl
{
auto timeout = deadline.deadline<std::chrono::steady_clock>().time_since_epoch();
struct timespec ts = durationToTimespec(timeout);
int r = _q_futex(addr(&futex), FUTEX_WAIT_BITSET, qintptr(expectedValue), quintptr(&ts),
nullptr, FUTEX_BITSET_MATCH_ANY);
long r = _q_futex(addr(&futex), FUTEX_WAIT_BITSET, qintptr(expectedValue), quintptr(&ts),
nullptr, FUTEX_BITSET_MATCH_ANY);
return r == 0 || errno != ETIMEDOUT;
}
template <typename Atomic> inline void futexWakeOne(Atomic &futex)