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authorVille Syrjälä <ville.syrjala@linux.intel.com>2020-04-28 20:19:40 +0300
committerVille Syrjälä <ville.syrjala@linux.intel.com>2020-09-01 13:38:34 +0300
commit8445e2c54c257e92084a451a0f20d6a7f3f9fa34 (patch)
tree0adb1fa4c33305ec7aa79747402605fc31a3c191
parent0e09c4fa72f9837ea8d78cb40ab0b52ff3252ea2 (diff)
downloadlinux-8445e2c54c257e92084a451a0f20d6a7f3f9fa34.tar.xz
drm: Replace mode->export_head with a boolean
In order to shrink drm_display_mode below the magic two cacheline mark in 64bit we need to shrink it by another 8 bytes. The easiest thing to eliminate is the 'export_head' list head which is only used during the getconnector ioctl to temporarly track which modes on the connector's mode list are to be exposed and which are to remain hidden. We can simply replace the list head with a boolean which we use to tag the modes that are to be exposed. If we make sure to clear the tags after we're done with them we don't even need an extra loop over the modes to reset the tags at the start of the getconnector ioctl. Conveniently we already have a hole for the boolean left behind by the removal of mode->private_flags. The final size of the struct is now 112 bytes on 32bit and 120 bytes on 64bit. Another alternative would be a temp bitmask so we wouldn't have to have anything in the mode struct itself. The main issue is how large of a bitmask do we need? I guess we could allocate it dynamically but that means an extra kcalloc() and an extra loop through the modes to count them first (or grow the bitmask with krealloc() as needed). CC: Sam Ravnborg <sam@ravnborg.org> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Emil Velikov <emil.l.velikov@gmail.com> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200428171940.19552-17-ville.syrjala@linux.intel.com Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
-rw-r--r--drivers/gpu/drm/drm_connector.c45
-rw-r--r--include/drm/drm_modes.h22
2 files changed, 42 insertions, 25 deletions
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 3d48ad1c3682..717c4e7271b0 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -2289,7 +2289,7 @@ static struct drm_encoder *drm_connector_get_encoder(struct drm_connector *conne
static bool
drm_mode_expose_to_userspace(const struct drm_display_mode *mode,
- const struct list_head *export_list,
+ const struct list_head *modes,
const struct drm_file *file_priv)
{
/*
@@ -2305,15 +2305,17 @@ drm_mode_expose_to_userspace(const struct drm_display_mode *mode,
* while preparing the list of user-modes.
*/
if (!file_priv->aspect_ratio_allowed) {
- struct drm_display_mode *mode_itr;
+ const struct drm_display_mode *mode_itr;
- list_for_each_entry(mode_itr, export_list, export_head)
- if (drm_mode_match(mode_itr, mode,
+ list_for_each_entry(mode_itr, modes, head) {
+ if (mode_itr->expose_to_userspace &&
+ drm_mode_match(mode_itr, mode,
DRM_MODE_MATCH_TIMINGS |
DRM_MODE_MATCH_CLOCK |
DRM_MODE_MATCH_FLAGS |
DRM_MODE_MATCH_3D_FLAGS))
return false;
+ }
}
return true;
@@ -2333,7 +2335,6 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
struct drm_mode_modeinfo u_mode;
struct drm_mode_modeinfo __user *mode_ptr;
uint32_t __user *encoder_ptr;
- LIST_HEAD(export_list);
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return -EOPNOTSUPP;
@@ -2377,25 +2378,30 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
out_resp->connection = connector->status;
/* 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, &export_list,
+ list_for_each_entry(mode, &connector->modes, head) {
+ WARN_ON(mode->expose_to_userspace);
+
+ if (drm_mode_expose_to_userspace(mode, &connector->modes,
file_priv)) {
- list_add_tail(&mode->export_head, &export_list);
+ mode->expose_to_userspace = true;
mode_count++;
}
+ }
/*
* This ioctl is called twice, once to determine how much space is
* needed, and the 2nd time to fill it.
- * The modes that need to be exposed to the user are maintained in the
- * 'export_list'. When the ioctl is called first time to determine the,
- * space, the export_list gets filled, to find the no.of modes. In the
- * 2nd time, the user modes are filled, one by one from the export_list.
*/
if ((out_resp->count_modes >= mode_count) && mode_count) {
copied = 0;
mode_ptr = (struct drm_mode_modeinfo __user *)(unsigned long)out_resp->modes_ptr;
- list_for_each_entry(mode, &export_list, export_head) {
+ list_for_each_entry(mode, &connector->modes, head) {
+ if (!mode->expose_to_userspace)
+ continue;
+
+ /* Clear the tag for the next time around */
+ mode->expose_to_userspace = false;
+
drm_mode_convert_to_umode(&u_mode, mode);
/*
* Reset aspect ratio flags of user-mode, if modes with
@@ -2406,13 +2412,26 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
if (copy_to_user(mode_ptr + copied,
&u_mode, sizeof(u_mode))) {
ret = -EFAULT;
+
+ /*
+ * Clear the tag for the rest of
+ * the modes for the next time around.
+ */
+ list_for_each_entry_continue(mode, &connector->modes, head)
+ mode->expose_to_userspace = false;
+
mutex_unlock(&dev->mode_config.mutex);
goto out;
}
copied++;
}
+ } else {
+ /* Clear the tag for the next time around */
+ list_for_each_entry(mode, &connector->modes, head)
+ mode->expose_to_userspace = false;
}
+
out_resp->count_modes = mode_count;
mutex_unlock(&dev->mode_config.mutex);
diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
index 7d686f9a29bf..cdf2a299ccd4 100644
--- a/include/drm/drm_modes.h
+++ b/include/drm/drm_modes.h
@@ -350,24 +350,22 @@ struct drm_display_mode {
u8 type;
/**
- * @head:
+ * @expose_to_userspace:
*
- * struct list_head for mode lists.
+ * Indicates whether the mode is to be exposed to the userspace.
+ * This is to maintain a set of exposed modes while preparing
+ * user-mode's list in drm_mode_getconnector ioctl. The purpose of
+ * this only lies in the ioctl function, and is not to be used
+ * outside the function.
*/
- struct list_head head;
+ bool expose_to_userspace;
/**
- * @export_head:
+ * @head:
*
- * struct list_head for modes to be exposed to the userspace.
- * This is to maintain a list of exposed modes while preparing
- * user-mode's list in drm_mode_getconnector ioctl. The purpose of this
- * list_head only lies in the ioctl function, and is not expected to be
- * used outside the function.
- * Once used, the stale pointers are not reset, but left as it is, to
- * avoid overhead of protecting it by mode_config.mutex.
+ * struct list_head for mode lists.
*/
- struct list_head export_head;
+ struct list_head head;
/**
* @name: