[Qemu-devel] [RFC PATCH v4 01/11] exec: Remove cpu from cpus list during cpu_exec_exit()

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

CPUState *cpu gets added to the cpus list during cpu_exec_init(). It
should be removed from cpu_exec_exit().

cpu_exec_init() is called from generic CPU::instance_finalize and some
archs like PowerPC call it from CPU unrealizefn. So ensure that we
dequeue the cpu only once.

Instead of introducing a new field CPUState.queued, I could have used
CPUState.cpu_index to check if the cpu is already dequeued from the list.
Since that doesn't work for CONFIG_USER_ONLY, I had to add a new field.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 exec.c            | 11 +++++++++++
 include/qom/cpu.h |  1 +
 2 files changed, 12 insertions(+)

diff --git a/exec.c b/exec.c
index 0a4a0c5..b196d68 100644
--- a/exec.c
+++ b/exec.c
@@ -550,6 +550,10 @@ void cpu_exec_exit(CPUState *cpu)
         return;
     }
 
+    if (cpu->queued) {
+        QTAILQ_REMOVE(&cpus, cpu, node);
+        cpu->queued = false;
+    }
     bitmap_clear(cpu_index_map, cpu->cpu_index, 1);
     cpu->cpu_index = -1;
 }
@@ -568,6 +572,12 @@ static int cpu_get_free_index(Error **errp)
 
 void cpu_exec_exit(CPUState *cpu)
 {
+    cpu_list_lock();
+    if (cpu->queued) {
+        QTAILQ_REMOVE(&cpus, cpu, node);
+        cpu->queued = false;
+    }
+    cpu_list_unlock();
 }
 #endif
 
@@ -595,6 +605,7 @@ void cpu_exec_init(CPUState *cpu, Error **errp)
         return;
     }
     QTAILQ_INSERT_TAIL(&cpus, cpu, node);
+    cpu->queued = true;
 #if defined(CONFIG_USER_ONLY)
     cpu_list_unlock();
 #endif
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 20aabc9..a00e3a8 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -284,6 +284,7 @@ struct CPUState {
     int gdb_num_regs;
     int gdb_num_g_regs;
     QTAILQ_ENTRY(CPUState) node;
+    bool queued;
 
     /* ice debug support */
     QTAILQ_HEAD(breakpoints_head, CPUBreakpoint) breakpoints;
-- 
2.1.0