diff mbox series

[v8,72/74] cpus-common: release BQL earlier in run_on_cpu

Message ID 20200326193156.4322-73-robert.foley@linaro.org
State Superseded
Headers show
Series per-CPU locks | expand

Commit Message

Robert Foley March 26, 2020, 7:31 p.m. UTC 
From: "Emilio G. Cota" <cota@braap.org>


After completing the conversion to per-CPU locks, there is no need
to release the BQL after having called cpu_kick.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

Signed-off-by: Emilio G. Cota <cota@braap.org>

Signed-off-by: Robert Foley <robert.foley@linaro.org>

---
 cpus-common.c | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

-- 
2.17.1
diff mbox series

Patch

diff --git a/cpus-common.c b/cpus-common.c
index 9ca025149e..f5daf2d518 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -137,6 +137,11 @@  void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
         return;
     }
 
+    /* We are going to sleep on the CPU lock, so release the BQL */
+    if (has_bql) {
+        qemu_mutex_unlock_iothread();
+    }
+
     wi.func = func;
     wi.data = data;
     wi.done = false;
@@ -145,21 +150,6 @@  void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
 
     cpu_mutex_lock(cpu);
     queue_work_on_cpu_locked(cpu, &wi);
-
-    /*
-     * We are going to sleep on the CPU lock, so release the BQL.
-     *
-     * During the transition to per-CPU locks, we release the BQL _after_
-     * having kicked the destination CPU (from queue_work_on_cpu_locked above).
-     * This makes sure that the enqueued work will be seen by the CPU
-     * after being woken up from the kick, since the CPU sleeps on the BQL.
-     * Once we complete the transition to per-CPU locks, we will release
-     * the BQL earlier in this function.
-     */
-    if (has_bql) {
-        qemu_mutex_unlock_iothread();
-    }
-
     while (!atomic_mb_read(&wi.done)) {
         CPUState *self_cpu = current_cpu;