[PATCH v2 4/5] Replace "iothread lock" with "BQL" in comments

[Stefan Hajnoczi <stefanha@redhat.com>]

The term "iothread lock" is obsolete. The APIs use Big QEMU Lock (BQL)
in their names. Update the code comments to use "BQL" instead of
"iothread lock".

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 docs/devel/reset.rst             |  2 +-
 hw/display/qxl.h                 |  2 +-
 include/exec/cpu-common.h        |  2 +-
 include/exec/memory.h            |  4 ++--
 include/exec/ramblock.h          |  2 +-
 include/migration/register.h     |  8 ++++----
 target/arm/internals.h           |  4 ++--
 accel/tcg/cputlb.c               |  4 ++--
 accel/tcg/tcg-accel-ops-icount.c |  2 +-
 hw/remote/mpqemu-link.c          |  2 +-
 migration/block-dirty-bitmap.c   | 10 +++++-----
 migration/block.c                | 24 ++++++++++++------------
 migration/colo.c                 |  2 +-
 migration/migration.c            |  2 +-
 migration/ram.c                  |  4 ++--
 system/physmem.c                 |  6 +++---
 target/arm/helper.c              |  2 +-
 ui/spice-core.c                  |  2 +-
 util/rcu.c                       |  2 +-
 audio/coreaudio.m                |  4 ++--
 ui/cocoa.m                       |  6 +++---
 21 files changed, 48 insertions(+), 48 deletions(-)

diff --git a/docs/devel/reset.rst b/docs/devel/reset.rst
index 38ed1790f7..d4e79718ba 100644
--- a/docs/devel/reset.rst
+++ b/docs/devel/reset.rst
@@ -19,7 +19,7 @@ Triggering reset
 
 This section documents the APIs which "users" of a resettable object should use
 to control it. All resettable control functions must be called while holding
-the iothread lock.
+the BQL.
 
 You can apply a reset to an object using ``resettable_assert_reset()``. You need
 to call ``resettable_release_reset()`` to release the object from reset. To
diff --git a/hw/display/qxl.h b/hw/display/qxl.h
index fdac14edad..e0a85a5ca4 100644
--- a/hw/display/qxl.h
+++ b/hw/display/qxl.h
@@ -159,7 +159,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(PCIQXLDevice, PCI_QXL)
  *
  * Use with care; by the time this function returns, the returned pointer is
  * not protected by RCU anymore.  If the caller is not within an RCU critical
- * section and does not hold the iothread lock, it must have other means of
+ * section and does not hold the BQL, it must have other means of
  * protecting the pointer, such as a reference to the region that includes
  * the incoming ram_addr_t.
  *
diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 41115d8919..fef3138d29 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -92,7 +92,7 @@ RAMBlock *qemu_ram_block_by_name(const char *name);
  *
  * By the time this function returns, the returned pointer is not protected
  * by RCU anymore.  If the caller is not within an RCU critical section and
- * does not hold the iothread lock, it must have other means of protecting the
+ * does not hold the BQL, it must have other means of protecting the
  * pointer, such as a reference to the memory region that owns the RAMBlock.
  */
 RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 831f7c996d..ad6466b07e 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -1962,7 +1962,7 @@ int memory_region_get_fd(MemoryRegion *mr);
  *
  * Use with care; by the time this function returns, the returned pointer is
  * not protected by RCU anymore.  If the caller is not within an RCU critical
- * section and does not hold the iothread lock, it must have other means of
+ * section and does not hold the BQL, it must have other means of
  * protecting the pointer, such as a reference to the region that includes
  * the incoming ram_addr_t.
  *
@@ -1979,7 +1979,7 @@ MemoryRegion *memory_region_from_host(void *ptr, ram_addr_t *offset);
  *
  * Use with care; by the time this function returns, the returned pointer is
  * not protected by RCU anymore.  If the caller is not within an RCU critical
- * section and does not hold the iothread lock, it must have other means of
+ * section and does not hold the BQL, it must have other means of
  * protecting the pointer, such as a reference to the region that includes
  * the incoming ram_addr_t.
  *
diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h
index 69c6a53902..3eb79723c6 100644
--- a/include/exec/ramblock.h
+++ b/include/exec/ramblock.h
@@ -34,7 +34,7 @@ struct RAMBlock {
     ram_addr_t max_length;
     void (*resized)(const char*, uint64_t length, void *host);
     uint32_t flags;
-    /* Protected by iothread lock.  */
+    /* Protected by the BQL.  */
     char idstr[256];
     /* RCU-enabled, writes protected by the ramlist lock */
     QLIST_ENTRY(RAMBlock) next;
diff --git a/include/migration/register.h b/include/migration/register.h
index fed1d04a3c..9ab1f79512 100644
--- a/include/migration/register.h
+++ b/include/migration/register.h
@@ -17,7 +17,7 @@
 #include "hw/vmstate-if.h"
 
 typedef struct SaveVMHandlers {
-    /* This runs inside the iothread lock.  */
+    /* This runs inside the BQL.  */
     SaveStateHandler *save_state;
 
     /*
@@ -30,7 +30,7 @@ typedef struct SaveVMHandlers {
     int (*save_live_complete_postcopy)(QEMUFile *f, void *opaque);
     int (*save_live_complete_precopy)(QEMUFile *f, void *opaque);
 
-    /* This runs both outside and inside the iothread lock.  */
+    /* This runs both outside and inside the BQL.  */
     bool (*is_active)(void *opaque);
     bool (*has_postcopy)(void *opaque);
 
@@ -43,14 +43,14 @@ typedef struct SaveVMHandlers {
      */
     bool (*is_active_iterate)(void *opaque);
 
-    /* This runs outside the iothread lock in the migration case, and
+    /* This runs outside the BQL in the migration case, and
      * within the lock in the savevm case.  The callback had better only
      * use data that is local to the migration thread or protected
      * by other locks.
      */
     int (*save_live_iterate)(QEMUFile *f, void *opaque);
 
-    /* This runs outside the iothread lock!  */
+    /* This runs outside the BQL!  */
     /* Note for save_live_pending:
      * must_precopy:
      * - must be migrated in precopy or in stopped state
diff --git a/target/arm/internals.h b/target/arm/internals.h
index 143d57c0fe..71d6c70bf3 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -940,7 +940,7 @@ static inline const char *aarch32_mode_name(uint32_t psr)
  *
  * Update the CPU_INTERRUPT_VIRQ bit in cs->interrupt_request, following
  * a change to either the input VIRQ line from the GIC or the HCR_EL2.VI bit.
- * Must be called with the iothread lock held.
+ * Must be called with the BQL held.
  */
 void arm_cpu_update_virq(ARMCPU *cpu);
 
@@ -949,7 +949,7 @@ void arm_cpu_update_virq(ARMCPU *cpu);
  *
  * Update the CPU_INTERRUPT_VFIQ bit in cs->interrupt_request, following
  * a change to either the input VFIQ line from the GIC or the HCR_EL2.VF bit.
- * Must be called with the iothread lock held.
+ * Must be called with the BQL held.
  */
 void arm_cpu_update_vfiq(ARMCPU *cpu);
 
diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index 5698a9fd8e..3facfcbb24 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -1975,7 +1975,7 @@ static void *atomic_mmu_lookup(CPUState *cpu, vaddr addr, MemOpIdx oi,
  * @size: number of bytes
  * @mmu_idx: virtual address context
  * @ra: return address into tcg generated code, or 0
- * Context: iothread lock held
+ * Context: BQL held
  *
  * Load @size bytes from @addr, which is memory-mapped i/o.
  * The bytes are concatenated in big-endian order with @ret_be.
@@ -2521,7 +2521,7 @@ static Int128 do_ld16_mmu(CPUState *cpu, vaddr addr,
  * @size: number of bytes
  * @mmu_idx: virtual address context
  * @ra: return address into tcg generated code, or 0
- * Context: iothread lock held
+ * Context: BQL held
  *
  * Store @size bytes at @addr, which is memory-mapped i/o.
  * The bytes to store are extracted in little-endian order from @val_le;
diff --git a/accel/tcg/tcg-accel-ops-icount.c b/accel/tcg/tcg-accel-ops-icount.c
index 5824d92580..9e1ae66f65 100644
--- a/accel/tcg/tcg-accel-ops-icount.c
+++ b/accel/tcg/tcg-accel-ops-icount.c
@@ -123,7 +123,7 @@ void icount_prepare_for_run(CPUState *cpu, int64_t cpu_budget)
 
     if (cpu->icount_budget == 0) {
         /*
-         * We're called without the iothread lock, so must take it while
+         * We're called without the BQL, so must take it while
          * we're calling timer handlers.
          */
         bql_lock();
diff --git a/hw/remote/mpqemu-link.c b/hw/remote/mpqemu-link.c
index d04ac93621..4394dc4d82 100644
--- a/hw/remote/mpqemu-link.c
+++ b/hw/remote/mpqemu-link.c
@@ -58,7 +58,7 @@ bool mpqemu_msg_send(MPQemuMsg *msg, QIOChannel *ioc, Error **errp)
     assert(qemu_in_coroutine() || !iothread);
 
     /*
-     * Skip unlocking/locking iothread lock when the IOThread is running
+     * Skip unlocking/locking BQL when the IOThread is running
      * in co-routine context. Co-routine context is asserted above
      * for IOThread case.
      * Also skip lock handling while in a co-routine in the main context.
diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 92e031b6fa..2708abf3d7 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -464,7 +464,7 @@ static void send_bitmap_bits(QEMUFile *f, DBMSaveState *s,
     g_free(buf);
 }
 
-/* Called with iothread lock taken.  */
+/* Called with the BQL taken.  */
 static void dirty_bitmap_do_save_cleanup(DBMSaveState *s)
 {
     SaveBitmapState *dbms;
@@ -479,7 +479,7 @@ static void dirty_bitmap_do_save_cleanup(DBMSaveState *s)
     }
 }
 
-/* Called with iothread lock taken. */
+/* Called with the BQL taken. */
 static int add_bitmaps_to_list(DBMSaveState *s, BlockDriverState *bs,
                                const char *bs_name, GHashTable *alias_map)
 {
@@ -598,7 +598,7 @@ static int add_bitmaps_to_list(DBMSaveState *s, BlockDriverState *bs,
     return 0;
 }
 
-/* Called with iothread lock taken. */
+/* Called with the BQL taken. */
 static int init_dirty_bitmap_migration(DBMSaveState *s)
 {
     BlockDriverState *bs;
@@ -607,7 +607,7 @@ static int init_dirty_bitmap_migration(DBMSaveState *s)
     BlockBackend *blk;
     GHashTable *alias_map = NULL;
 
-    /* Runs in the migration thread, but holds the iothread lock */
+    /* Runs in the migration thread, but holds the BQL */
     GLOBAL_STATE_CODE();
     GRAPH_RDLOCK_GUARD_MAINLOOP();
 
@@ -742,7 +742,7 @@ static int dirty_bitmap_save_iterate(QEMUFile *f, void *opaque)
     return s->bulk_completed;
 }
 
-/* Called with iothread lock taken.  */
+/* Called with the BQL taken.  */
 
 static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)
 {
diff --git a/migration/block.c b/migration/block.c
index 4a675b92bc..61d4daf022 100644
--- a/migration/block.c
+++ b/migration/block.c
@@ -66,7 +66,7 @@ typedef struct BlkMigDevState {
     /* Protected by block migration lock.  */
     int64_t completed_sectors;
 
-    /* During migration this is protected by iothread lock / AioContext.
+    /* During migration this is protected by BQL / AioContext.
      * Allocation and free happen during setup and cleanup respectively.
      */
     BdrvDirtyBitmap *dirty_bitmap;
@@ -101,7 +101,7 @@ typedef struct BlkMigState {
     int prev_progress;
     int bulk_completed;
 
-    /* Lock must be taken _inside_ the iothread lock and any AioContexts.  */
+    /* Lock must be taken _inside_ the BQL and any AioContexts.  */
     QemuMutex lock;
 } BlkMigState;
 
@@ -117,7 +117,7 @@ static void blk_mig_unlock(void)
     qemu_mutex_unlock(&block_mig_state.lock);
 }
 
-/* Must run outside of the iothread lock during the bulk phase,
+/* Must run outside of the BQL during the bulk phase,
  * or the VM will stall.
  */
 
@@ -334,7 +334,7 @@ static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
     return (bmds->cur_sector >= total_sectors);
 }
 
-/* Called with iothread lock taken.  */
+/* Called with the BQL taken.  */
 
 static int set_dirty_tracking(void)
 {
@@ -361,7 +361,7 @@ fail:
     return ret;
 }
 
-/* Called with iothread lock taken.  */
+/* Called with the BQL taken.  */
 
 static void unset_dirty_tracking(void)
 {
@@ -512,7 +512,7 @@ static void blk_mig_reset_dirty_cursor(void)
     }
 }
 
-/* Called with iothread lock and AioContext taken.  */
+/* Called with the BQL and AioContext taken.  */
 
 static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
                                  int is_async)
@@ -594,7 +594,7 @@ error:
     return ret;
 }
 
-/* Called with iothread lock taken.
+/* Called with the BQL taken.
  *
  * return value:
  * 0: too much data for max_downtime
@@ -658,7 +658,7 @@ static int flush_blks(QEMUFile *f)
     return ret;
 }
 
-/* Called with iothread lock taken.  */
+/* Called with the BQL taken.  */
 
 static int64_t get_remaining_dirty(void)
 {
@@ -676,7 +676,7 @@ static int64_t get_remaining_dirty(void)
 
 
 
-/* Called with iothread lock taken.  */
+/* Called with the BQL taken.  */
 static void block_migration_cleanup_bmds(void)
 {
     BlkMigDevState *bmds;
@@ -706,7 +706,7 @@ static void block_migration_cleanup_bmds(void)
     }
 }
 
-/* Called with iothread lock taken.  */
+/* Called with the BQL taken.  */
 static void block_migration_cleanup(void *opaque)
 {
     BlkMigBlock *blk;
@@ -783,7 +783,7 @@ static int block_save_iterate(QEMUFile *f, void *opaque)
             }
             ret = 0;
         } else {
-            /* Always called with iothread lock taken for
+            /* Always called with the BQL taken for
              * simplicity, block_save_complete also calls it.
              */
             bql_lock();
@@ -811,7 +811,7 @@ static int block_save_iterate(QEMUFile *f, void *opaque)
     return (delta_bytes > 0);
 }
 
-/* Called with iothread lock taken.  */
+/* Called with the BQL taken.  */
 
 static int block_save_complete(QEMUFile *f, void *opaque)
 {
diff --git a/migration/colo.c b/migration/colo.c
index 2a74efdd77..315e31fe32 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -945,7 +945,7 @@ int coroutine_fn colo_incoming_co(void)
     qemu_thread_join(&th);
     bql_lock();
 
-    /* We hold the global iothread lock, so it is safe here */
+    /* We hold the global BQL, so it is safe here */
     colo_release_ram_cache();
 
     return 0;
diff --git a/migration/migration.c b/migration/migration.c
index be74c714d6..fb0a1a766f 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2567,7 +2567,7 @@ fail:
 
 /**
  * migration_maybe_pause: Pause if required to by
- * migrate_pause_before_switchover called with the iothread locked
+ * migrate_pause_before_switchover called with the BQL locked
  * Returns: 0 on success
  */
 static int migration_maybe_pause(MigrationState *s,
diff --git a/migration/ram.c b/migration/ram.c
index 08dc7e2909..890f31cf66 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2395,7 +2395,7 @@ static void ram_save_cleanup(void *opaque)
 
     /* We don't use dirty log with background snapshots */
     if (!migrate_background_snapshot()) {
-        /* caller have hold iothread lock or is in a bh, so there is
+        /* caller have hold BQL or is in a bh, so there is
          * no writing race against the migration bitmap
          */
         if (global_dirty_tracking & GLOBAL_DIRTY_MIGRATION) {
@@ -3131,7 +3131,7 @@ out:
  *
  * Returns zero to indicate success or negative on error
  *
- * Called with iothread lock
+ * Called with the BQL
  *
  * @f: QEMUFile where to send the data
  * @opaque: RAMState pointer
diff --git a/system/physmem.c b/system/physmem.c
index 4937e67bad..cc68a79763 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -799,7 +799,7 @@ static RAMBlock *qemu_get_ram_block(ram_addr_t addr)
     abort();
 
 found:
-    /* It is safe to write mru_block outside the iothread lock.  This
+    /* It is safe to write mru_block outside the BQL.  This
      * is what happens:
      *
      *     mru_block = xxx
@@ -1597,7 +1597,7 @@ int qemu_ram_get_fd(RAMBlock *rb)
     return rb->fd;
 }
 
-/* Called with iothread lock held.  */
+/* Called with the BQL held.  */
 void qemu_ram_set_idstr(RAMBlock *new_block, const char *name, DeviceState *dev)
 {
     RAMBlock *block;
@@ -1625,7 +1625,7 @@ void qemu_ram_set_idstr(RAMBlock *new_block, const char *name, DeviceState *dev)
     }
 }
 
-/* Called with iothread lock held.  */
+/* Called with the BQL held.  */
 void qemu_ram_unset_idstr(RAMBlock *block)
 {
     /* FIXME: arch_init.c assumes that this is not called throughout
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 4a978d1102..16ec643337 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -5824,7 +5824,7 @@ static void do_hcr_write(CPUARMState *env, uint64_t value, uint64_t valid_mask)
      * Updates to VI and VF require us to update the status of
      * virtual interrupts, which are the logical OR of these bits
      * and the state of the input lines from the GIC. (This requires
-     * that we have the iothread lock, which is done by marking the
+     * that we have the BQL, which is done by marking the
      * reginfo structs as ARM_CP_IO.)
      * Note that if a write to HCR pends a VIRQ or VFIQ it is never
      * possible for it to be taken immediately, because VIRQ and
diff --git a/ui/spice-core.c b/ui/spice-core.c
index b6ee495a8f..37b277fd09 100644
--- a/ui/spice-core.c
+++ b/ui/spice-core.c
@@ -217,7 +217,7 @@ static void channel_event(int event, SpiceChannelEventInfo *info)
      * not do that.  It isn't that easy to fix it in spice and even
      * when it is fixed we still should cover the already released
      * spice versions.  So detect that we've been called from another
-     * thread and grab the iothread lock if so before calling qemu
+     * thread and grab the BQL if so before calling qemu
      * functions.
      */
     bool need_lock = !qemu_thread_is_self(&me);
diff --git a/util/rcu.c b/util/rcu.c
index bb7f633b5c..fa32c942e4 100644
--- a/util/rcu.c
+++ b/util/rcu.c
@@ -409,7 +409,7 @@ static void rcu_init_complete(void)
 
     qemu_event_init(&rcu_call_ready_event, false);
 
-    /* The caller is assumed to have iothread lock, so the call_rcu thread
+    /* The caller is assumed to have BQL, so the call_rcu thread
      * must have been quiescent even after forking, just recreate it.
      */
     qemu_thread_create(&thread, "call_rcu", call_rcu_thread,
diff --git a/audio/coreaudio.m b/audio/coreaudio.m
index 9d2db9883c..ab632b9bbb 100644
--- a/audio/coreaudio.m
+++ b/audio/coreaudio.m
@@ -299,7 +299,7 @@ static ret_type glue(coreaudio_, name)args_decl             \
 #undef COREAUDIO_WRAPPER_FUNC
 
 /*
- * callback to feed audiooutput buffer. called without iothread lock.
+ * callback to feed audiooutput buffer. called without BQL.
  * allowed to lock "buf_mutex", but disallowed to have any other locks.
  */
 static OSStatus audioDeviceIOProc(
@@ -538,7 +538,7 @@ static void update_device_playback_state(coreaudioVoiceOut *core)
     }
 }
 
-/* called without iothread lock. */
+/* called without BQL. */
 static OSStatus handle_voice_change(
     AudioObjectID in_object_id,
     UInt32 in_number_addresses,
diff --git a/ui/cocoa.m b/ui/cocoa.m
index 5ebb535070..eb99064bee 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -113,7 +113,7 @@ static void cocoa_switch(DisplayChangeListener *dcl,
 static QemuClipboardInfo *cbinfo;
 static QemuEvent cbevent;
 
-// Utility functions to run specified code block with iothread lock held
+// Utility functions to run specified code block with the BQL held
 typedef void (^CodeBlock)(void);
 typedef bool (^BoolCodeBlock)(void);
 
@@ -548,7 +548,7 @@ - (void) setContentDimensions
 
 - (void) updateUIInfoLocked
 {
-    /* Must be called with the iothread lock, i.e. via updateUIInfo */
+    /* Must be called with the BQL, i.e. via updateUIInfo */
     NSSize frameSize;
     QemuUIInfo info;
 
@@ -2075,7 +2075,7 @@ static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
      * Create the menu entries which depend on QEMU state (for consoles
      * and removable devices). These make calls back into QEMU functions,
      * which is OK because at this point we know that the second thread
-     * holds the iothread lock and is synchronously waiting for us to
+     * holds the BQL and is synchronously waiting for us to
      * finish.
      */
     add_console_menu_entries();
-- 
2.43.0