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>

3 files changed, 4 insertions, 4 deletions

diff --git a/hw/misc/edu.c b/hw/misc/edu.c
index e64a246d3f..2a976ca2b1 100644
--- a/hw/misc/edu.c
+++ b/hw/misc/edu.c
@@ -355,9 +355,9 @@ static void *edu_fact_thread(void *opaque)
         smp_mb__after_rmw();
 
         if (qatomic_read(&edu->status) & EDU_STATUS_IRQFACT) {
-            qemu_mutex_lock_iothread();
+            bql_lock();
             edu_raise_irq(edu, FACT_IRQ);
-            qemu_mutex_unlock_iothread();
+            bql_unlock();
         }
     }
 
diff --git a/hw/misc/imx6_src.c b/hw/misc/imx6_src.c
index d20727e20b..0c6003559f 100644
--- a/hw/misc/imx6_src.c
+++ b/hw/misc/imx6_src.c
@@ -131,7 +131,7 @@ static void imx6_clear_reset_bit(CPUState *cpu, run_on_cpu_data data)
     struct SRCSCRResetInfo *ri = data.host_ptr;
     IMX6SRCState *s = ri->s;
 
-    assert(qemu_mutex_iothread_locked());
+    assert(bql_locked());
 
     s->regs[SRC_SCR] = deposit32(s->regs[SRC_SCR], ri->reset_bit, 1, 0);
     DPRINTF("reg[%s] <= 0x%" PRIx32 "\n",
diff --git a/hw/misc/imx7_src.c b/hw/misc/imx7_src.c
index 24a0b4618c..b3725ff6e7 100644
--- a/hw/misc/imx7_src.c
+++ b/hw/misc/imx7_src.c
@@ -136,7 +136,7 @@ static void imx7_clear_reset_bit(CPUState *cpu, run_on_cpu_data data)
     struct SRCSCRResetInfo *ri = data.host_ptr;
     IMX7SRCState *s = ri->s;
 
-    assert(qemu_mutex_iothread_locked());
+    assert(bql_locked());
 
     s->regs[SRC_A7RCR0] = deposit32(s->regs[SRC_A7RCR0], ri->reset_bit, 1, 0);