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, 2 insertions, 2 deletions

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 24347ab0f7..92e031b6fa 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -774,7 +774,7 @@ static void dirty_bitmap_state_pending(void *opaque,
     SaveBitmapState *dbms;
     uint64_t pending = 0;
 
-    qemu_mutex_lock_iothread();
+    bql_lock();
 
     QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
         uint64_t gran = bdrv_dirty_bitmap_granularity(dbms->bitmap);
@@ -784,7 +784,7 @@ static void dirty_bitmap_state_pending(void *opaque,
         pending += DIV_ROUND_UP(sectors * BDRV_SECTOR_SIZE, gran);
     }
 
-    qemu_mutex_unlock_iothread();
+    bql_unlock();
 
     trace_dirty_bitmap_state_pending(pending);