https://bugs.kde.org/show_bug.cgi?id=423963
--- Comment #25 from Christoph Cullmann <cullm...@kde.org> ---
As additional info that might be useful:
Before we ported our stuff to Qt 6.x, we did use Qt 5.15 (not with all
patches).
There we never had such issues, below is the diff of the 3rdparty/forkfd
directories between the Qt 5.15 and 6.x version now in use here:
diff -u -r -w ../../qt5/src/qtbase/src/3rdparty/forkfd/forkfd.c
src/qtbase/src/3rdparty/forkfd/forkfd.c
--- ../../qt5/src/qtbase/src/3rdparty/forkfd/forkfd.c 2020-10-06
17:17:50.510596533 +0200
+++ src/qtbase/src/3rdparty/forkfd/forkfd.c 2021-04-01 10:53:12.909416546
+0200
@@ -240,6 +240,9 @@
}
}
+#ifdef __GNUC__
+__attribute__((unused))
+#endif
static int convertForkfdWaitFlagsToWaitFlags(int ffdoptions)
{
int woptions = WEXITED;
@@ -617,12 +620,6 @@
* fork(), such as not calling the functions registered with pthread_atfork().
* If that's necessary, pass this flag.
*
- * @li @c FFD_VFORK_SEMANTICS Tell forkfd() to use semantics similar to
- * vfork(), if that's available. For example, on Linux with pidfd support
- * available, this will add the CLONE_VFORK option. On most other systems,
- * including Linux without pidfd support, this option does nothing, as using
- * the actual vfork() system call would cause a race condition.
- *
* The file descriptor returned by forkfd() supports the following operations:
*
* @li read(2) When the child process exits, then the buffer supplied to
diff -u -r -w ../../qt5/src/qtbase/src/3rdparty/forkfd/forkfd.h
src/qtbase/src/3rdparty/forkfd/forkfd.h
--- ../../qt5/src/qtbase/src/3rdparty/forkfd/forkfd.h 2020-10-06
17:17:50.510596533 +0200
+++ src/qtbase/src/3rdparty/forkfd/forkfd.h 2021-04-01 10:53:12.909416546
+0200
@@ -41,7 +41,6 @@
#define FFD_CLOEXEC 1
#define FFD_NONBLOCK 2
#define FFD_USE_FORK 4
-#define FFD_VFORK_SEMANTICS 8
#define FFD_CHILD_PROCESS (-2)
diff -u -r -w ../../qt5/src/qtbase/src/3rdparty/forkfd/forkfd_linux.c
src/qtbase/src/3rdparty/forkfd/forkfd_linux.c
--- ../../qt5/src/qtbase/src/3rdparty/forkfd/forkfd_linux.c 2020-10-06
17:17:50.510596533 +0200
+++ src/qtbase/src/3rdparty/forkfd/forkfd_linux.c 2021-04-01
10:53:12.909416546 +0200
@@ -82,7 +82,7 @@
return syscall(__NR_clone, cloneflags, child_stack, stack_size, ptid,
newtls, ctid);
#elif defined(__arc__) || defined(__arm__) || defined(__aarch64__) ||
defined(__mips__) || \
defined(__nds32__) || defined(__hppa__) || defined(__powerpc__) ||
defined(__i386__) || \
- defined(__x86_64__) || defined(__xtensa__) || defined(__alpha__)
+ defined(__x86_64__) || defined(__xtensa__) || defined(__alpha__) ||
defined(__riscv)
/* ctid and newtls are inverted on CONFIG_CLONE_BACKWARDS architectures,
* but since both values are 0, there's no harm. */
return syscall(__NR_clone, cloneflags, child_stack, ptid, ctid, newtls);
@@ -147,10 +147,10 @@
}
*system = 1;
- unsigned long cloneflags = CLONE_PIDFD;
- if (flags & FFD_VFORK_SEMANTICS)
- cloneflags |= CLONE_VFORK;
+ unsigned long cloneflags = CLONE_PIDFD | SIGCHLD;
pid = sys_clone(cloneflags, &pidfd);
+ if (pid < 0)
+ return pid;
if (ppid)
*ppid = pid;
@@ -173,7 +173,7 @@
{
siginfo_t si;
int ret;
- int options = __WALL | convertForkfdWaitFlagsToWaitFlags(ffdoptions);
+ int options = convertForkfdWaitFlagsToWaitFlags(ffdoptions);
if ((options & WNOHANG) == 0) {
/* check if the file descriptor is non-blocking */
--
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