commit 027d9a7d2911e993cdcbd21c7c35d1dd058f05bb
author Alex Bennée <alex.bennee@linaro.org> Fri Sep 30 22:30:59 2016 +0100
committer Paolo Bonzini <pbonzini@redhat.com> Tue Oct 04 10:00:26 2016 +0200
tree b215197742f489c9af5dd1737ee60be313190f49
parent ce7cf6a973f4b614162b9518954d441fa5e32fc6

cpu: atomically modify cpu->exit_request

ThreadSanitizer picks up potential races although we already use
barriers to ensure things are in the correct order when processing exit
requests. For true C11 defined behaviour across threads we need to use
relaxed atomic_set/atomic_read semantics to reassure tsan.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20160930213106.20186-9-alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

cpu-exec.c

diff --git a/cpu-exec.c b/cpu-exec.c
index 8823d23..e114fcd 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -192,7 +192,7 @@
         /* We were asked to stop executing TBs (probably a pending
          * interrupt. We've now stopped, so clear the flag.
          */
-        cpu->tcg_exit_req = 0;
+        atomic_set(&cpu->tcg_exit_req, 0);
     }
     return ret;
 }
@@ -490,8 +490,8 @@
             *last_tb = NULL;
         }
     }
-    if (unlikely(cpu->exit_request || replay_has_interrupt())) {
-        cpu->exit_request = 0;
+    if (unlikely(atomic_read(&cpu->exit_request) || replay_has_interrupt())) {
+        atomic_set(&cpu->exit_request, 0);
         cpu->exception_index = EXCP_INTERRUPT;
         cpu_loop_exit(cpu);
     }
@@ -503,7 +503,7 @@
 {
     uintptr_t ret;
 
-    if (unlikely(cpu->exit_request)) {
+    if (unlikely(atomic_read(&cpu->exit_request))) {
         return;
     }