[Intel-gfx] [PATCH 6/7] drm: Don't walk fb list twice in getresources
Daniel Vetter
daniel at ffwll.ch
Sat Dec 10 21:30:40 UTC 2016
On Fri, Dec 09, 2016 at 09:57:45PM +0000, Chris Wilson wrote:
> On Fri, Dec 09, 2016 at 03:19:43PM +0100, Daniel Vetter wrote:
> > We can be more clever than that and merge the 2 list walking loops.
> > It's all under the one mutex critical section anyway, so nothing funny
> > can happen.
> >
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> > drivers/gpu/drm/drm_mode_config.c | 28 +++++++++++-----------------
> > 1 file changed, 11 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> > index 64c2971478db..a6205a92dfee 100644
> > --- a/drivers/gpu/drm/drm_mode_config.c
> > +++ b/drivers/gpu/drm/drm_mode_config.c
> > @@ -84,7 +84,6 @@ int drm_mode_getresources(struct drm_device *dev, void *data,
> > struct drm_file *file_priv)
> > {
> > struct drm_mode_card_res *card_res = data;
> > - struct list_head *lh;
> > struct drm_framebuffer *fb;
> > struct drm_connector *connector;
> > struct drm_crtc *crtc;
> > @@ -105,25 +104,20 @@ int drm_mode_getresources(struct drm_device *dev, void *data,
> >
> >
> > mutex_lock(&file_priv->fbs_lock);
> > - /*
> > - * For the non-control nodes we need to limit the list of resources
> > - * by IDs in the group list for this node
> > - */
> > - list_for_each(lh, &file_priv->fbs)
> > - fb_count++;
> > -
> > /* handle this in 4 parts */
> > /* FBs */
> > - if (card_res->count_fbs >= fb_count) {
> > - copied = 0;
> > - fb_id = (uint32_t __user *)(unsigned long)card_res->fb_id_ptr;
> > - list_for_each_entry(fb, &file_priv->fbs, filp_head) {
> > - if (put_user(fb->base.id, fb_id + copied)) {
> > - mutex_unlock(&file_priv->fbs_lock);
> > - return -EFAULT;
> > - }
> > - copied++;
> > + copied = 0;
> > + fb_id = (uint32_t __user *)(unsigned long)card_res->fb_id_ptr;
> > + list_for_each_entry(fb, &file_priv->fbs, filp_head) {
> > + fb_count++;
> > + if (fb_count > card_res->count_fbs)
> > + continue;
> > +
> > + if (put_user(fb->base.id, fb_id + copied)) {
> > + mutex_unlock(&file_priv->fbs_lock);
> > + return -EFAULT;
> > }
> > + copied++;
>
> if (fb_count < card_res->count_fbs &&
> put_user(fb->base.id fb_id + fb_count) {
> }
> fb_count++; // no need for copied
>
> I'd just like for one style :) Otoh, this seems reasonable to apply to
> crtc/encoders/connectors as well, and on the other we already have a
> counter for the others. Hmm, setting count = copied in the previous
> patch is thereby wrong (change in uABI).
It's only a change if the connector count changed between when we read it
and when we walked the list. But I guess you've convinced me that
simplifying this loops more is a good idea, and this way we can use the
same style for all of them.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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