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>

2 files changed, 10 insertions, 10 deletions

diff --git a/hw/intc/arm_gicv3_cpuif.c b/hw/intc/arm_gicv3_cpuif.c
index ab1a00508e..77c2a6dd3b 100644
--- a/hw/intc/arm_gicv3_cpuif.c
+++ b/hw/intc/arm_gicv3_cpuif.c
@@ -934,7 +934,7 @@ void gicv3_cpuif_update(GICv3CPUState *cs)
     ARMCPU *cpu = ARM_CPU(cs->cpu);
     CPUARMState *env = &cpu->env;
 
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
 
     trace_gicv3_cpuif_update(gicv3_redist_affid(cs), cs->hppi.irq,
                              cs->hppi.grp, cs->hppi.prio);
diff --git a/hw/intc/s390_flic.c b/hw/intc/s390_flic.c
index 212f268581..f4a848460b 100644
--- a/hw/intc/s390_flic.c
+++ b/hw/intc/s390_flic.c
@@ -106,7 +106,7 @@ static int qemu_s390_clear_io_flic(S390FLICState *fs, uint16_t subchannel_id,
     QEMUS390FlicIO *cur, *next;
     uint8_t isc;
 
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
     if (!(flic->pending & FLIC_PENDING_IO)) {
         return 0;
     }
@@ -223,7 +223,7 @@ uint32_t qemu_s390_flic_dequeue_service(QEMUS390FLICState *flic)
 {
     uint32_t tmp;
 
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
     g_assert(flic->pending & FLIC_PENDING_SERVICE);
     tmp = flic->service_param;
     flic->service_param = 0;
@@ -238,7 +238,7 @@ QEMUS390FlicIO *qemu_s390_flic_dequeue_io(QEMUS390FLICState *flic, uint64_t cr6)
     QEMUS390FlicIO *io;
     uint8_t isc;
 
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
     if (!(flic->pending & CR6_TO_PENDING_IO(cr6))) {
         return NULL;
     }
@@ -262,7 +262,7 @@ QEMUS390FlicIO *qemu_s390_flic_dequeue_io(QEMUS390FLICState *flic, uint64_t cr6)
 
 void qemu_s390_flic_dequeue_crw_mchk(QEMUS390FLICState *flic)
 {
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
     g_assert(flic->pending & FLIC_PENDING_MCHK_CR);
     flic->pending &= ~FLIC_PENDING_MCHK_CR;
 }
@@ -271,7 +271,7 @@ static void qemu_s390_inject_service(S390FLICState *fs, uint32_t parm)
 {
     QEMUS390FLICState *flic = s390_get_qemu_flic(fs);
 
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
     /* multiplexing is good enough for sclp - kvm does it internally as well */
     flic->service_param |= parm;
     flic->pending |= FLIC_PENDING_SERVICE;
@@ -287,7 +287,7 @@ static void qemu_s390_inject_io(S390FLICState *fs, uint16_t subchannel_id,
     QEMUS390FLICState *flic = s390_get_qemu_flic(fs);
     QEMUS390FlicIO *io;
 
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
     io = g_new0(QEMUS390FlicIO, 1);
     io->id = subchannel_id;
     io->nr = subchannel_nr;
@@ -304,7 +304,7 @@ static void qemu_s390_inject_crw_mchk(S390FLICState *fs)
 {
     QEMUS390FLICState *flic = s390_get_qemu_flic(fs);
 
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
     flic->pending |= FLIC_PENDING_MCHK_CR;
 
     qemu_s390_flic_notify(FLIC_PENDING_MCHK_CR);
@@ -330,7 +330,7 @@ bool qemu_s390_flic_has_crw_mchk(QEMUS390FLICState *flic)
 
 bool qemu_s390_flic_has_any(QEMUS390FLICState *flic)
 {
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
     return !!flic->pending;
 }
 
@@ -340,7 +340,7 @@ static void qemu_s390_flic_reset(DeviceState *dev)
     QEMUS390FlicIO *cur, *next;
     int isc;
 
-    g_assert(qemu_mutex_iothread_locked());
+    g_assert(bql_locked());
     flic->simm = 0;
     flic->nimm = 0;
     flic->pending = 0;