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QEventDispatcherUNIX: remove the fallback to pipes on eventfd systems

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Linux has had it since 2.6.23, which is positively ancient from our
perspective. No one runs Qt on systems anywhere near that old (I'd be
amazed if anyone managed on CentOS / RHEL 7, which carries Linux 3.10).
And we don't deal with ENOSYS on FreeBSD either.

The removal is accomplished by dead code elimination: it's still
compiled on Linux and FreeBSD.

Drive-by
 - use NSDMI in QThreadPipe
 - remove EINTR_LOOP for eventfd_write(3): it can't be interrupted

Change-Id: I63b988479db546dabffcfffd1766e2c7acc6da46
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
This commit is contained in:
Thiago Macieira 2023-06-08 21:20:57 -07:00
parent f174ae254b
commit 41f4139306
2 changed files with 15 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
src/corelib/kernel/qeventdispatcher_unix.cpp
View File

@ -45,11 +45,6 @@ static const char *socketType(QSocketNotifier::Type type)
QThreadPipe::QThreadPipe()
{
fds[0] = -1;
fds[1] = -1;
#if defined(Q_OS_VXWORKS)
name[0] = '\0';
#endif
}
QThreadPipe::~QThreadPipe()
@ -57,7 +52,7 @@ QThreadPipe::~QThreadPipe()
if (fds[0] >= 0)
close(fds[0]);
if (fds[1] >= 0)
if (!QT_CONFIG(eventfd) && fds[1] >= 0)
close(fds[1]);
#if defined(Q_OS_VXWORKS)
@ -106,11 +101,13 @@ bool QThreadPipe::init()
initThreadPipeFD(fds[0]);
fds[1] = fds[0];
#else
int ret;
# if QT_CONFIG(eventfd)
if ((fds[0] = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC)) >= 0)
return true;
ret = fds[0] = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
# endif
if (qt_safe_pipe(fds, O_NONBLOCK) == -1) {
if (!QT_CONFIG(eventfd))
ret = qt_safe_pipe(fds, O_NONBLOCK);
if (ret == -1) {
perror("QThreadPipe: Unable to create pipe");
return false;
}
@ -128,13 +125,8 @@ void QThreadPipe::wakeUp()
{
if (wakeUps.testAndSetAcquire(0, 1)) {
#if QT_CONFIG(eventfd)
if (fds[1] == -1) {
// eventfd
eventfd_t value = 1;
int ret;
EINTR_LOOP(ret, eventfd_write(fds[0], value));
return;
}
eventfd_write(fds[0], 1);
return;
#endif
char c = 0;
qt_safe_write(fds[1], &c, 1);
@ -156,13 +148,10 @@ int QThreadPipe::check(const pollfd &pfd)
::ioctl(fds[0], FIOFLUSH, 0);
#else
# if QT_CONFIG(eventfd)
if (fds[1] == -1) {
// eventfd
eventfd_t value;
eventfd_read(fds[0], &value);
} else
eventfd_t value;
eventfd_read(fds[0], &value);
# endif
{
if (!QT_CONFIG(eventfd)) {
while (::read(fds[0], c, sizeof(c)) > 0) {}
}
#endif

8
src/corelib/kernel/qeventdispatcher_unix_p.h
View File

@ -51,13 +51,13 @@ struct QThreadPipe
int check(const pollfd &pfd);
// note for eventfd(7) support:
// if fds[1] is -1, then eventfd(7) is in use and is stored in fds[0]
int fds[2];
// fds[0] stores the eventfd, fds[1] is unused
int fds[2] = { -1, -1 };
QAtomicInt wakeUps;
#if defined(Q_OS_VXWORKS)
static const int len_name = 20;
char name[len_name];
static constexpr int len_name = 20;
char name[len_name] = {};
#endif
};