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, 7 insertions, 7 deletions

diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index c0631f9cf4..b0ed2e6aeb 100644
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -403,7 +403,7 @@ void kvm_xen_maybe_deassert_callback(CPUState *cs)
 
     /* If the evtchn_upcall_pending flag is cleared, turn the GSI off. */
     if (!vi->evtchn_upcall_pending) {
-        qemu_mutex_lock_iothread();
+        bql_lock();
         /*
          * Check again now we have the lock, because it may have been
          * asserted in the interim. And we don't want to take the lock
@@ -413,7 +413,7 @@ void kvm_xen_maybe_deassert_callback(CPUState *cs)
             X86_CPU(cs)->env.xen_callback_asserted = false;
             xen_evtchn_set_callback_level(0);
         }
-        qemu_mutex_unlock_iothread();
+        bql_unlock();
     }
 }
 
@@ -773,9 +773,9 @@ static bool handle_set_param(struct kvm_xen_exit *exit, X86CPU *cpu,
 
     switch (hp.index) {
     case HVM_PARAM_CALLBACK_IRQ:
-        qemu_mutex_lock_iothread();
+        bql_lock();
         err = xen_evtchn_set_callback_param(hp.value);
-        qemu_mutex_unlock_iothread();
+        bql_unlock();
         xen_set_long_mode(exit->u.hcall.longmode);
         break;
     default:
@@ -1408,7 +1408,7 @@ int kvm_xen_soft_reset(void)
     CPUState *cpu;
     int err;
 
-    assert(qemu_mutex_iothread_locked());
+    assert(bql_locked());
 
     trace_kvm_xen_soft_reset();
 
@@ -1481,9 +1481,9 @@ static int schedop_shutdown(CPUState *cs, uint64_t arg)
         break;
 
     case SHUTDOWN_soft_reset:
-        qemu_mutex_lock_iothread();
+        bql_lock();
         ret = kvm_xen_soft_reset();
-        qemu_mutex_unlock_iothread();
+        bql_unlock();
         break;
 
     default: