The threaded VNC servers messed up with QEMU fd handlers without
any kind of locking, and that can cause some nasty race conditions.
The IO-Thread provides appropriate locking primitives to avoid that.
This patch makes CONFIG_VNC_THREAD depends on CONFIG_IO_THREAD,
and add lock and unlock calls around the two faulty calls.
Thanks to Jan Kiszka for helping me solve this issue.
Cc: Jan Kiszka <jan.kiszka@xxxxxx>
Signed-off-by: Corentin Chary <corentin.chary@xxxxxxxxx>
---
configure | 9 +++++++++
ui/vnc-jobs-async.c | 4 ++++
2 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/configure b/configure
index 5513d3e..c8c1ac1 100755
--- a/configure
+++ b/configure
@@ -2455,6 +2455,15 @@ if test \( "$cpu" = "i386" -o "$cpu" = "x86_64" \) -a \
roms="optionrom"
fi
+# VNC Thread depends on IO Thread
+if test "$vnc_thread" = "yes" -a "$io_thread" != "yes"; then
+ echo
+ echo "ERROR: VNC thread depends on IO thread which isn't enabled."
+ echo "Please use --enable-io-thread if you want to enable it."
+ echo
+ exit 1
+fi
+
echo "Install prefix $prefix"
echo "BIOS directory `eval echo $datadir`"
diff --git a/ui/vnc-jobs-async.c b/ui/vnc-jobs-async.c
index f596247..093c0d4 100644
--- a/ui/vnc-jobs-async.c
+++ b/ui/vnc-jobs-async.c
@@ -260,7 +260,9 @@ static int vnc_worker_thread_loop(VncJobQueue *queue)
goto disconnected;
}
+ qemu_mutex_lock_iothread();
vnc_write(job->vs, vs.output.buffer, vs.output.offset);
+ qemu_mutex_unlock_iothread();
disconnected:
/* Copy persistent encoding data */
@@ -269,7 +271,9 @@ disconnected:
vnc_unlock_output(job->vs);
if (flush) {
+ qemu_mutex_lock_iothread();
vnc_flush(job->vs);
+ qemu_mutex_unlock_iothread();
}
vnc_lock_queue(queue);
--
1.7.3.4
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