From 068a5ea02f62853116788a2c42d8851a94bb7567 Mon Sep 17 00:00:00 2001 From: "Emilio G. Cota" Date: Sun, 19 Aug 2018 05:13:35 -0400 Subject: qom: convert the CPU list to RCU Iterating over the list without using atomics is undefined behaviour, since the list can be modified concurrently by other threads (e.g. every time a new thread is created in user-mode). Fix it by implementing the CPU list as an RCU QTAILQ. This requires a little bit of extra work to traverse list in reverse order (see previous patch), but other than that the conversion is trivial. Signed-off-by: Emilio G. Cota Message-Id: <20180819091335.22863-12-cota@braap.org> Signed-off-by: Paolo Bonzini --- linux-user/main.c | 2 +- linux-user/syscall.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'linux-user') diff --git a/linux-user/main.c b/linux-user/main.c index ea00dd9..923cbb7 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -126,7 +126,7 @@ void fork_end(int child) Discard information about the parent threads. */ CPU_FOREACH_SAFE(cpu, next_cpu) { if (cpu != thread_cpu) { - QTAILQ_REMOVE(&cpus, cpu, node); + QTAILQ_REMOVE_RCU(&cpus, cpu, node); } } qemu_init_cpu_list(); diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 202aa77..3c3c1ae 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -8157,7 +8157,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, TaskState *ts; /* Remove the CPU from the list. */ - QTAILQ_REMOVE(&cpus, cpu, node); + QTAILQ_REMOVE_RCU(&cpus, cpu, node); cpu_list_unlock(); -- cgit v1.1