[Qemu-devel] Re: [PATCH v3 3/4] qxl/spice: remove qemu_mutex_{un, }lock_iothread around dispatcher

[Hans de Goede]

Looks good now, ack:

Acked-by: Hans de Goede <address@hidden>


On 03/16/2011 04:52 PM, Alon Levy wrote:
> with the previous patch making sure get_command no longer needs to lock,
> there is no reason to drop the qemu iothread mutex in qxl.c and in
> ui/spice-display.c
>
> The only location where the lock remains are the cursor related callbacks,
> that path is currently broken. It is only triggered if running spice and sdl,
> which is broken already before that.
> ---
>   hw/qxl.c           |    8 --------
>   ui/spice-display.c |   19 +++----------------
>   2 files changed, 3 insertions(+), 24 deletions(-)
>
> diff --git a/hw/qxl.c b/hw/qxl.c
> index 64580f1..cf3c938 100644
> --- a/hw/qxl.c
> +++ b/hw/qxl.c
> @@ -670,10 +670,8 @@ static void qxl_hard_reset(PCIQXLDevice *d, int loadvm)
>       dprint(d, 1, "%s: start%s\n", __FUNCTION__,
>              loadvm ? " (loadvm)" : "");
>
> -    qemu_mutex_unlock_iothread();
>       d->ssd.worker->reset_cursor(d->ssd.worker);
>       d->ssd.worker->reset_image_cache(d->ssd.worker);
> -    qemu_mutex_lock_iothread();
>       qxl_reset_surfaces(d);
>       qxl_reset_memslots(d);
>
> @@ -803,9 +801,7 @@ static void qxl_reset_surfaces(PCIQXLDevice *d)
>   {
>       dprint(d, 1, "%s:\n", __FUNCTION__);
>       d->mode = QXL_MODE_UNDEFINED;
> -    qemu_mutex_unlock_iothread();
>       d->ssd.worker->destroy_surfaces(d->ssd.worker);
> -    qemu_mutex_lock_iothread();
>       memset(&d->guest_surfaces.cmds, 0, sizeof(d->guest_surfaces.cmds));
>   }
>
> @@ -874,9 +870,7 @@ static void qxl_destroy_primary(PCIQXLDevice *d)
>       dprint(d, 1, "%s\n", __FUNCTION__);
>
>       d->mode = QXL_MODE_UNDEFINED;
> -    qemu_mutex_unlock_iothread();
>       d->ssd.worker->destroy_primary_surface(d->ssd.worker, 0);
> -    qemu_mutex_lock_iothread();
>   }
>
>   static void qxl_set_mode(PCIQXLDevice *d, int modenr, int loadvm)
> @@ -946,10 +940,8 @@ static void ioport_write(void *opaque, uint32_t addr, 
> uint32_t val)
>       case QXL_IO_UPDATE_AREA:
>       {
>           QXLRect update = d->ram->update_area;
> -        qemu_mutex_unlock_iothread();
>           d->ssd.worker->update_area(d->ssd.worker, d->ram->update_surface,
>                                      &update, NULL, 0, 0);
> -        qemu_mutex_lock_iothread();
>           break;
>       }
>       case QXL_IO_NOTIFY_CMD:
> diff --git a/ui/spice-display.c b/ui/spice-display.c
> index bdd14b8..ecb22cc 100644
> --- a/ui/spice-display.c
> +++ b/ui/spice-display.c
> @@ -62,13 +62,7 @@ void qemu_spice_rect_union(QXLRect *dest, const QXLRect *r)
>       dest->right = MAX(dest->right, r->right);
>   }
>
> -/*
> - * Called from spice server thread context (via interface_get_command).
> - *
> - * We must aquire the global qemu mutex here to make sure the
> - * DisplayState (+DisplaySurface) we are accessing doesn't change
> - * underneath us.
> - */
> +/* Called from io-thread context (via pipe_read) */
>   SimpleSpiceUpdate *qemu_spice_create_update(SimpleSpiceDisplay *ssd)
>   {
>       SimpleSpiceUpdate *update;
> @@ -78,9 +72,7 @@ SimpleSpiceUpdate 
> *qemu_spice_create_update(SimpleSpiceDisplay *ssd)
>       uint8_t *src, *dst;
>       int by, bw, bh;
>
> -    qemu_mutex_lock_iothread();
>       if (qemu_spice_rect_is_empty(&ssd->dirty)) {
> -        qemu_mutex_unlock_iothread();
>           return NULL;
>       };
>
> @@ -141,7 +133,6 @@ SimpleSpiceUpdate 
> *qemu_spice_create_update(SimpleSpiceDisplay *ssd)
>       cmd->data = (intptr_t)drawable;
>
>       memset(&ssd->dirty, 0, sizeof(ssd->dirty));
> -    qemu_mutex_unlock_iothread();
>       return update;
>   }
>
> @@ -169,6 +160,7 @@ void qemu_spice_create_host_memslot(SimpleSpiceDisplay *ssd)
>       ssd->worker->add_memslot(ssd->worker,&memslot);
>   }
>
> +/* called from iothread (main) or a vcpu-thread */
>   void qemu_spice_create_host_primary(SimpleSpiceDisplay *ssd)
>   {
>       QXLDevSurfaceCreate surface;
> @@ -186,18 +178,14 @@ void qemu_spice_create_host_primary(SimpleSpiceDisplay 
> *ssd)
>       surface.mem        = (intptr_t)ssd->buf;
>       surface.group_id   = MEMSLOT_GROUP_HOST;
>
> -    qemu_mutex_unlock_iothread();
>       ssd->worker->create_primary_surface(ssd->worker, 0,&surface);
> -    qemu_mutex_lock_iothread();
>   }
>
>   void qemu_spice_destroy_host_primary(SimpleSpiceDisplay *ssd)
>   {
>       dprint(1, "%s:\n", __FUNCTION__);
>
> -    qemu_mutex_unlock_iothread();
>       ssd->worker->destroy_primary_surface(ssd->worker, 0);
> -    qemu_mutex_lock_iothread();
>   }
>
>   void qemu_spice_vm_change_state_handler(void *opaque, int running, int reason)
> @@ -207,9 +195,7 @@ void qemu_spice_vm_change_state_handler(void *opaque, int 
> running, int reason)
>       if (running) {
>           ssd->worker->start(ssd->worker);
>       } else {
> -        qemu_mutex_unlock_iothread();
>           ssd->worker->stop(ssd->worker);
> -        qemu_mutex_lock_iothread();
>       }
>       ssd->running = running;
>   }
> @@ -233,6 +219,7 @@ void qemu_spice_display_update(SimpleSpiceDisplay *ssd,
>       qemu_spice_rect_union(&ssd->dirty,&update_area);
>   }
>
> +/* called only from iothread (main) */
>   void qemu_spice_display_resize(SimpleSpiceDisplay *ssd)
>   {
>       dprint(1, "%s:\n", __FUNCTION__);