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[23/35] cpus: use broadcast on qemu_pause_cond

Message ID 1458581313-19045-24-git-send-email-mdroth@linux.vnet.ibm.com
State New
Headers show

Commit Message

Michael Roth March 21, 2016, 5:28 p.m. UTC 
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Jiri saw a hang on pause_all_vcpus called from postcopy_start,
where the cpus are all apparently stopped ('stopped' flag set)
but pause_all_vcpus is still stuck on a cond_wait on qemu_paused_cond.
We suspect this is happening if a qmp_stop is called at about the
same time as the postcopy code calls that pause_all_vcpus;
although they both should have the main lock held, Paolo spotted
the cond_wait unlocks the global lock so perhaps they both
could end up waiting at the same time?

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reported-by: Jiri Denemark <jdenemar@redhat.com>
Message-Id: <1453716498-27238-1-git-send-email-dgilbert@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 96bce6831bd19b61e965384427741d805c7234c3)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 cpus.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/cpus.c b/cpus.c
index 43676fa..747f14d 100644
--- a/cpus.c
+++ b/cpus.c
@@ -986,7 +986,7 @@  static void qemu_wait_io_event_common(CPUState *cpu)
     if (cpu->stop) {
         cpu->stop = false;
         cpu->stopped = true;
-        qemu_cond_signal(&qemu_pause_cond);
+        qemu_cond_broadcast(&qemu_pause_cond);
     }
     flush_queued_work(cpu);
     cpu->thread_kicked = false;
@@ -1387,7 +1387,7 @@  void cpu_stop_current(void)
         current_cpu->stop = false;
         current_cpu->stopped = true;
         cpu_exit(current_cpu);
-        qemu_cond_signal(&qemu_pause_cond);
+        qemu_cond_broadcast(&qemu_pause_cond);
     }
 }