system/cpus: rename qemu_mutex_lock_iothread() to bql_lock()

The Big QEMU Lock (BQL) has many names and they are confusing. The
actual QemuMutex variable is called qemu_global_mutex but it's commonly
referred to as the BQL in discussions and some code comments. The
locking APIs, however, are called qemu_mutex_lock_iothread() and
qemu_mutex_unlock_iothread().

The "iothread" name is historic and comes from when the main thread was
split into into KVM vcpu threads and the "iothread" (now called the main
loop thread). I have contributed to the confusion myself by introducing
a separate --object iothread, a separate concept unrelated to the BQL.

The "iothread" name is no longer appropriate for the BQL. Rename the
locking APIs to:
- void bql_lock(void)
- void bql_unlock(void)
- bool bql_locked(void)

There are more APIs with "iothread" in their names. Subsequent patches
will rename them. There are also comments and documentation that will be
updated in later patches.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Fabiano Rosas <farosas@suse.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Acked-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20240102153529.486531-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index 62d86b8be2..1d2e85746f 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -90,13 +90,13 @@ static int64_t do_calculate_dirtyrate(DirtyPageRecord dirty_pages,
 
 void global_dirty_log_change(unsigned int flag, bool start)
 {
-    qemu_mutex_lock_iothread();
+    bql_lock();
     if (start) {
         memory_global_dirty_log_start(flag);
     } else {
         memory_global_dirty_log_stop(flag);
     }
-    qemu_mutex_unlock_iothread();
+    bql_unlock();
 }
 
 /*
@@ -106,12 +106,12 @@ void global_dirty_log_change(unsigned int flag, bool start)
  */
 static void global_dirty_log_sync(unsigned int flag, bool one_shot)
 {
-    qemu_mutex_lock_iothread();
+    bql_lock();
     memory_global_dirty_log_sync(false);
     if (one_shot) {
         memory_global_dirty_log_stop(flag);
     }
-    qemu_mutex_unlock_iothread();
+    bql_unlock();
 }
 
 static DirtyPageRecord *vcpu_dirty_stat_alloc(VcpuStat *stat)
@@ -609,7 +609,7 @@ static void calculate_dirtyrate_dirty_bitmap(struct DirtyRateConfig config)
     int64_t start_time;
     DirtyPageRecord dirty_pages;
 
-    qemu_mutex_lock_iothread();
+    bql_lock();
     memory_global_dirty_log_start(GLOBAL_DIRTY_DIRTY_RATE);
 
     /*
@@ -626,7 +626,7 @@ static void calculate_dirtyrate_dirty_bitmap(struct DirtyRateConfig config)
      * KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE cap is enabled.
      */
     dirtyrate_manual_reset_protect();
-    qemu_mutex_unlock_iothread();
+    bql_unlock();
 
     record_dirtypages_bitmap(&dirty_pages, true);