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 --- cpus-common.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'cpus-common.c') diff --git a/cpus-common.c b/cpus-common.c index 59f751ecf9..98dd8c6ff1 100644 --- a/cpus-common.c +++ b/cpus-common.c @@ -84,7 +84,7 @@ void cpu_list_add(CPUState *cpu) } else { assert(!cpu_index_auto_assigned); } - QTAILQ_INSERT_TAIL(&cpus, cpu, node); + QTAILQ_INSERT_TAIL_RCU(&cpus, cpu, node); qemu_mutex_unlock(&qemu_cpu_list_lock); finish_safe_work(cpu); @@ -101,7 +101,7 @@ void cpu_list_remove(CPUState *cpu) assert(!(cpu_index_auto_assigned && cpu != QTAILQ_LAST(&cpus, CPUTailQ))); - QTAILQ_REMOVE(&cpus, cpu, node); + QTAILQ_REMOVE_RCU(&cpus, cpu, node); cpu->cpu_index = UNASSIGNED_CPU_INDEX; qemu_mutex_unlock(&qemu_cpu_list_lock); } -- cgit 1.4.1