linux-user: In fork_end(), remove correct CPUs from CPU list

In fork_end(), we must fix the list of current CPUs to match the fact
that the child of the fork has only one thread. Unfortunately we were
removing the wrong CPUs from the list, which meant that if the child
subsequently did an exclusive operation it would deadlock in
start_exclusive() waiting for a sibling CPU which didn't exist.

In particular this could cause hangs doing git submodule init
operations, as reported in https://bugs.launchpad.net/qemu/+bug/955379
comment #47.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
This commit is contained in:
Peter Maydell 2016-06-07 17:31:04 +01:00 committed by Riku Voipio
parent da2a34f7f9
commit 014628a705

View File

@ -130,7 +130,7 @@ void fork_end(int child)
Discard information about the parent threads. */
CPU_FOREACH_SAFE(cpu, next_cpu) {
if (cpu != thread_cpu) {
QTAILQ_REMOVE(&cpus, thread_cpu, node);
QTAILQ_REMOVE(&cpus, cpu, node);
}
}
pending_cpus = 0;