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, 3 insertions, 3 deletions

diff --git a/target/arm/tcg/m_helper.c b/target/arm/tcg/m_helper.c
index a26adb75aa..d1f1e02acc 100644
--- a/target/arm/tcg/m_helper.c
+++ b/target/arm/tcg/m_helper.c
@@ -373,8 +373,8 @@ void HELPER(v7m_preserve_fp_state)(CPUARMState *env)
     bool ts = is_secure && (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_TS_MASK);
     bool take_exception;
 
-    /* Take the iothread lock as we are going to touch the NVIC */
-    qemu_mutex_lock_iothread();
+    /* Take the BQL as we are going to touch the NVIC */
+    bql_lock();
 
     /* Check the background context had access to the FPU */
     if (!v7m_cpacr_pass(env, is_secure, is_priv)) {
@@ -428,7 +428,7 @@ void HELPER(v7m_preserve_fp_state)(CPUARMState *env)
     take_exception = !stacked_ok &&
         armv7m_nvic_can_take_pending_exception(env->nvic);
 
-    qemu_mutex_unlock_iothread();
+    bql_unlock();
 
     if (take_exception) {
         raise_exception_ra(env, EXCP_LAZYFP, 0, 1, GETPC());