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tcg: synchronize exit_request and tcg_current_cpu accesses

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Synchronize the remaining pair of accesses in cpu_signal.  These should
be necessary on Windows as well, at least in theory.  Probably
SuspendProcess and ResumeProcess introduce some implicit memory
barrier.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2015-08-18 06:43:15 -07:00
parent ab096a75cd
commit aed807c8e2
2 changed files with 11 additions and 5 deletions
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2
cpu-exec.c
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@ -372,7 +372,7 @@ int cpu_exec(CPUState *cpu)
atomic_mb_set(&tcg_current_cpu, cpu);
rcu_read_lock();
if (unlikely(exit_request)) {
if (unlikely(atomic_mb_read(&exit_request))) {
cpu->exit_request = 1;
}

14
cpus.c
View File

@ -663,11 +663,15 @@ static void cpu_handle_guest_debug(CPUState *cpu)
static void cpu_signal(int sig)
{
CPUState *cpu = atomic_mb_read(&tcg_current_cpu);
CPUState *cpu;
/* Ensure whatever caused the exit has reached the CPU threads before
* writing exit_request.
*/
atomic_mb_set(&exit_request, 1);
cpu = atomic_mb_read(&tcg_current_cpu);
if (cpu) {
cpu_exit(cpu);
}
exit_request = 1;
}
#ifdef CONFIG_LINUX
@ -1063,7 +1067,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
}
/* process any pending work */
exit_request = 1;
atomic_mb_set(&exit_request, 1);
while (1) {
tcg_exec_all();
@ -1441,7 +1445,9 @@ static void tcg_exec_all(void)
break;
}
}
exit_request = 0;
/* Pairs with smp_wmb in qemu_cpu_kick. */
atomic_mb_set(&exit_request, 0);
}
void list_cpus(FILE *f, fprintf_function cpu_fprintf, const char *optarg)