[PATCH 09/13] drm: Tighten locking in drm_mode_getconnector
Daniel Vetter
daniel at ffwll.ch
Sun Dec 18 13:40:44 UTC 2016
On Fri, Dec 16, 2016 at 10:03:32AM -0500, Sean Paul wrote:
> On Tue, Dec 13, 2016 at 6:08 PM, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> > - Modeset state needs mode_config->connection mutex, that covers
> > figuring out the encoder, and reading properties (since in the
> > atomic case those need to look at connector->state).
> >
> > - Don't hold any locks for stuff that's invariant (i.e. possible
> > connectors).
> >
> > - Same for connector lookup and unref, those don't need any locks.
> >
> > - And finally the probe stuff is only protected by mode_config->mutex.
> >
> > While at it updated the kerneldoc for these fields in drm_connector
> > and add docs explaining what's protected by which locks.
> >
>
>
> Reviewed-by: Sean Paul <seanpaul at chromium.org>
Merged up to this patch to drm-misc, thanks for the reviews to everyone.
-Daniel
>
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> > drivers/gpu/drm/drm_connector.c | 92 ++++++++++++++++++++---------------------
> > include/drm/drm_connector.h | 23 +++++++++--
> > 2 files changed, 63 insertions(+), 52 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> > index 0d4728704099..44b556d5d40c 100644
> > --- a/drivers/gpu/drm/drm_connector.c
> > +++ b/drivers/gpu/drm/drm_connector.c
> > @@ -1160,43 +1160,65 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
> >
> > memset(&u_mode, 0, sizeof(struct drm_mode_modeinfo));
> >
> > - mutex_lock(&dev->mode_config.mutex);
> > -
> > connector = drm_connector_lookup(dev, out_resp->connector_id);
> > - if (!connector) {
> > - ret = -ENOENT;
> > - goto out_unlock;
> > - }
> > + if (!connector)
> > + return -ENOENT;
> > +
> > + drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> > + encoder = drm_connector_get_encoder(connector);
> > + if (encoder)
> > + out_resp->encoder_id = encoder->base.id;
> > + else
> > + out_resp->encoder_id = 0;
> > +
> > + ret = drm_mode_object_get_properties(&connector->base, file_priv->atomic,
> > + (uint32_t __user *)(unsigned long)(out_resp->props_ptr),
> > + (uint64_t __user *)(unsigned long)(out_resp->prop_values_ptr),
> > + &out_resp->count_props);
> > + drm_modeset_unlock(&dev->mode_config.connection_mutex);
> > + if (ret)
> > + goto out_unref;
> >
> > for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++)
> > if (connector->encoder_ids[i] != 0)
> > encoders_count++;
> >
> > + if ((out_resp->count_encoders >= encoders_count) && encoders_count) {
> > + copied = 0;
> > + encoder_ptr = (uint32_t __user *)(unsigned long)(out_resp->encoders_ptr);
> > + for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
> > + if (connector->encoder_ids[i] != 0) {
> > + if (put_user(connector->encoder_ids[i],
> > + encoder_ptr + copied)) {
> > + ret = -EFAULT;
> > + goto out_unref;
> > + }
> > + copied++;
> > + }
> > + }
> > + }
> > + out_resp->count_encoders = encoders_count;
> > +
> > + out_resp->connector_id = connector->base.id;
> > + out_resp->connector_type = connector->connector_type;
> > + out_resp->connector_type_id = connector->connector_type_id;
> > +
> > + mutex_lock(&dev->mode_config.mutex);
> > if (out_resp->count_modes == 0) {
> > connector->funcs->fill_modes(connector,
> > dev->mode_config.max_width,
> > dev->mode_config.max_height);
> > }
> >
> > - /* delayed so we get modes regardless of pre-fill_modes state */
> > - list_for_each_entry(mode, &connector->modes, head)
> > - if (drm_mode_expose_to_userspace(mode, file_priv))
> > - mode_count++;
> > -
> > - out_resp->connector_id = connector->base.id;
> > - out_resp->connector_type = connector->connector_type;
> > - out_resp->connector_type_id = connector->connector_type_id;
> > out_resp->mm_width = connector->display_info.width_mm;
> > out_resp->mm_height = connector->display_info.height_mm;
> > out_resp->subpixel = connector->display_info.subpixel_order;
> > out_resp->connection = connector->status;
> >
> > - drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> > - encoder = drm_connector_get_encoder(connector);
> > - if (encoder)
> > - out_resp->encoder_id = encoder->base.id;
> > - else
> > - out_resp->encoder_id = 0;
> > + /* delayed so we get modes regardless of pre-fill_modes state */
> > + list_for_each_entry(mode, &connector->modes, head)
> > + if (drm_mode_expose_to_userspace(mode, file_priv))
> > + mode_count++;
> >
> > /*
> > * This ioctl is called twice, once to determine how much space is
> > @@ -1219,36 +1241,10 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
> > }
> > }
> > out_resp->count_modes = mode_count;
> > -
> > - ret = drm_mode_object_get_properties(&connector->base, file_priv->atomic,
> > - (uint32_t __user *)(unsigned long)(out_resp->props_ptr),
> > - (uint64_t __user *)(unsigned long)(out_resp->prop_values_ptr),
> > - &out_resp->count_props);
> > - if (ret)
> > - goto out;
> > -
> > - if ((out_resp->count_encoders >= encoders_count) && encoders_count) {
> > - copied = 0;
> > - encoder_ptr = (uint32_t __user *)(unsigned long)(out_resp->encoders_ptr);
> > - for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
> > - if (connector->encoder_ids[i] != 0) {
> > - if (put_user(connector->encoder_ids[i],
> > - encoder_ptr + copied)) {
> > - ret = -EFAULT;
> > - goto out;
> > - }
> > - copied++;
> > - }
> > - }
> > - }
> > - out_resp->count_encoders = encoders_count;
> > -
> > out:
> > - drm_modeset_unlock(&dev->mode_config.connection_mutex);
> > -
> > - drm_connector_unreference(connector);
> > -out_unlock:
> > mutex_unlock(&dev->mode_config.mutex);
> > +out_unref:
> > + drm_connector_unreference(connector);
> >
> > return ret;
> > }
> > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> > index a24559ef8bb7..9af4141165d3 100644
> > --- a/include/drm/drm_connector.h
> > +++ b/include/drm/drm_connector.h
> > @@ -559,9 +559,6 @@ struct drm_cmdline_mode {
> > * @interlace_allowed: can this connector handle interlaced modes?
> > * @doublescan_allowed: can this connector handle doublescan?
> > * @stereo_allowed: can this connector handle stereo modes?
> > - * @modes: modes available on this connector (from fill_modes() + user)
> > - * @status: one of the drm_connector_status enums (connected, not, or unknown)
> > - * @probed_modes: list of modes derived directly from the display
> > * @funcs: connector control functions
> > * @edid_blob_ptr: DRM property containing EDID if present
> > * @properties: property tracking for this connector
> > @@ -631,11 +628,27 @@ struct drm_connector {
> > * Protected by @mutex.
> > */
> > bool registered;
> > +
> > + /**
> > + * @modes:
> > + * Modes available on this connector (from fill_modes() + user).
> > + * Protected by dev->mode_config.mutex.
> > + */
> > struct list_head modes; /* list of modes on this connector */
> >
> > + /**
> > + * @status:
> > + * One of the drm_connector_status enums (connected, not, or unknown).
> > + * Protected by dev->mode_config.mutex.
> > + */
> > enum drm_connector_status status;
> >
> > - /* these are modes added by probing with DDC or the BIOS */
> > + /**
> > + * @probed_modes:
> > + * These are modes added by probing with DDC or the BIOS, before
> > + * filtering is applied. Used by the probe helpers.Protected by
> > + * dev->mode_config.mutex.
> > + */
> > struct list_head probed_modes;
> >
> > /**
> > @@ -644,6 +657,8 @@ struct drm_connector {
> > * flat panels in embedded systems, the driver should initialize the
> > * display_info.width_mm and display_info.height_mm fields with the
> > * physical size of the display.
> > + *
> > + * Protected by dev->mode_config.mutex.
> > */
> > struct drm_display_info display_info;
> > const struct drm_connector_funcs *funcs;
> > --
> > 2.11.0
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
>
>
> --
> Sean Paul, Software Engineer, Google / Chromium OS
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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