Followup-For: Bug #862558
Control: reassign -1 plasma-workspace
Control: affects -1 uim-qt5 uim-mozc
Control: tags -1 + patch
Dear Maintainer,
This is a bug in ksplashqml. An upstream commit
https://cgit.kde.org/plasma-workspace.git/commit/?id=56d2c15b9acb9c4b57398b281685807c3191f622
has caused this problem.
x-session-manag,133,kdetest /usr/bin/x-session-manager
├─(ksplashqml,232)
├─ssh-agent,191 /usr/bin/im-launch x-session-manager
├─uim-toolbar,220
│ ├─{llvmpipe-0},235
│ ├─{llvmpipe-1},236
│ ├─{llvmpipe-2},237
│ └─{llvmpipe-3},238
└─uim-xim,219
ksplashqml,233,kdetest Breeze --pid
├─mozc_server,239
│ ├─{IPCServer},244
│ ├─{QueueTimer},240
│ ├─{QueueTimer},243
│ └─{WatchDog},242
├─uim-candwin-qt5,245 -v
│ ├─{QDBusConnection},249
│ └─{QXcbEventReader},248
├─{QDBusConnection},255
├─{QQmlThread},254
├─{QXcbEventReader},234
├─{llvmpipe-0},250
├─{llvmpipe-1},251
├─{llvmpipe-2},252
└─{llvmpipe-3},253
# strace -f -p 133
strace: Process 133 attached
read(3, ^Cstrace: Process 133 detached
<detached ...>
It looks like the parent process (133), x-session-manager (startkde
script), is waiting for the stdout of the ksplashqml process (232),
but which is now defunct. Its child process(es) may be writing to the
same fd.
# ls -l /proc/133/fd/3
lr-x------ 1 kdetest kdetest 64 May 31 05:13 /proc/133/fd/3 -> pipe:[88694]
The direct child of the ksplashqml process (233), the splash screen daemon,
closes the file descriptor at ksplash/ksplashqml/main.cpp:97.
# ls -l /proc/233/fd/1
ls: cannot access '/proc/233/fd/1': No such file or directory
One of the children of the process (239), mozc_server, is holding the fd:
# ls -l /proc/239/fd/1
l-wx------ 1 kdetest kdetest 64 May 31 05:14 /proc/239/fd/1 -> pipe:[88694]
So the startkde process has finished reading the pid number string from
the now-defunct process, but is still waiting for another write(s) until
the (shared) fd has been closed.
This mozc_server process has been started during uim-qt5
(a QPlatformInputContext) startup in the SplashApp
initialization phase at ksplash/ksplashqml/main.cpp:92.
Due to the upstream commit the splash screen daemon does not close file
descriptors before the SplashApp initialization, thus its subprocess
shares the fds.
The commit log states Wayland initialization of this daemon needs the
channels. While it may require open file descriptors 0, 1 or 2,
no one should expect the process to talk to the parent through the
descriptors, since the splash screen is a daemon.
An attached patch reverts the commit and redirects the file descriptors
to /dev/null.
Regards,
--
YOSHINO Yoshihito <yy.y.ja...@gmail.com>
--- plasma-workspace-5.8.6.orig/ksplash/ksplashqml/main.cpp
+++ plasma-workspace-5.8.6/ksplash/ksplashqml/main.cpp
@@ -24,6 +24,9 @@
#include <QTextStream>
#include <iostream>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
#include <unistd.h>
void logMessageHandler(QtMsgType type, const char *msg)
@@ -83,6 +86,16 @@ int main(int argc, char **argv)
return 0;
}
+
+ int devNull = open("/dev/null", O_RDWR);
+ if (devNull == -1) {
+ return -1;
+ }
+ // replace stdin,stdout,stderr, otherwise startkde will block
+ dup2(devNull, 0);
+ dup2(devNull, 1);
+ dup2(devNull, 2);
+ close(devNull);
}
//enable to send log output to /tmp/ksplash
@@ -91,13 +104,6 @@ int main(int argc, char **argv)
QQuickWindow::setDefaultAlphaBuffer(true);
SplashApp app(argc, argv);
- if (!test && !nofork) {
- // close stdin,stdout,stderr, otherwise startkde will block
- close(0);
- close(1);
- close(2);
- }
-
return app.exec();
}
