Nouveau - Jul 2018 - [PATCH v2 2/3] drm/nouveau: Fix runtime PM leak in nv50_disp_atomic_commit()

This is the latest version of
https://patchwork.freedesktop.org/series/45862/ . One new patch has been
added that also addresses some additional issues I found with
pmops_runtime_idle that would stop nouveau from suspending the GPU when
running under X.

Additionally,
"drm/nouveau: Fix runtime PM leak in nv50_disp_atomic_commit()" has
had
it's CC to stable removed.

Lyude Paul (3):
  drm/nouveau: Fix runtime PM leak in drm_open()
  drm/nouveau: Fix runtime PM leak in nv50_disp_atomic_commit()
  drm/nouveau: Remove bogus crtc check in pmops_runtime_idle

 drivers/gpu/drm/nouveau/dispnv50/disp.c |  2 +-
 drivers/gpu/drm/nouveau/nouveau_drm.c   | 17 ++++-------------
 2 files changed, 5 insertions(+), 14 deletions(-)

-- 
2.17.1

Noticed this as I was skimming through, if we fail to allocate memory
for cli we'll end up returning without dropping the runtime PM ref we
got. Additionally, we'll even return the wrong return code! (ret most
likely will == 0 here, we want -ENOMEM).

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Lukas Wunner <lukas at wunner.de>
---
 drivers/gpu/drm/nouveau/nouveau_drm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c
b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 0452b18d36b9..0f668e275ee1 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -919,8 +919,10 @@ nouveau_drm_open(struct drm_device *dev, struct drm_file
*fpriv)
 	get_task_comm(tmpname, current);
 	snprintf(name, sizeof(name), "%s[%d]", tmpname,
pid_nr(fpriv->pid));
 
-	if (!(cli = kzalloc(sizeof(*cli), GFP_KERNEL)))
-		return ret;
+	if (!(cli = kzalloc(sizeof(*cli), GFP_KERNEL))) {
+		ret = -ENOMEM;
+		goto done;
+	}
 
 	ret = nouveau_cli_init(drm, name, cli);
 	if (ret)
-- 
2.17.1

A CRTC being enabled doesn't mean it's on! It doesn't even
necessarily
mean it's being used. This fixes runtime PM leaks on the P50 I've got
next to me.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Cc: stable at vger.kernel.org
---
 drivers/gpu/drm/nouveau/dispnv50/disp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index d9da69c83ae7..9bae4db84cfb 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1878,7 +1878,7 @@ nv50_disp_atomic_commit(struct drm_device *dev,
 		nv50_disp_atomic_commit_tail(state);
 
 	drm_for_each_crtc(crtc, dev) {
-		if (crtc->state->enable) {
+		if (crtc->state->active) {
 			if (!drm->have_disp_power_ref) {
 				drm->have_disp_power_ref = true;
 				return 0;
-- 
2.17.1

This both uses the legacy modesetting structures in a racy manner, and
additionally also doesn't even check the right variable (enabled != the
CRTC is actually turned on for atomic).

This fixes issues on my P50 regarding the dedicated GPU not entering
runtime suspend.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Cc: stable at vger.kernel.org
---
 drivers/gpu/drm/nouveau/nouveau_drm.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c
b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 0f668e275ee1..c7ec86d6c3c9 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -881,22 +881,11 @@ nouveau_pmops_runtime_resume(struct device *dev)
 static int
 nouveau_pmops_runtime_idle(struct device *dev)
 {
-	struct pci_dev *pdev = to_pci_dev(dev);
-	struct drm_device *drm_dev = pci_get_drvdata(pdev);
-	struct nouveau_drm *drm = nouveau_drm(drm_dev);
-	struct drm_crtc *crtc;
-
 	if (!nouveau_pmops_runtime()) {
 		pm_runtime_forbid(dev);
 		return -EBUSY;
 	}
 
-	list_for_each_entry(crtc, &drm->dev->mode_config.crtc_list, head) {
-		if (crtc->enabled) {
-			DRM_DEBUG_DRIVER("failing to power off - crtc active\n");
-			return -EBUSY;
-		}
-	}
 	pm_runtime_mark_last_busy(dev);
 	pm_runtime_autosuspend(dev);
 	/* we don't want the main rpm_idle to call suspend - we want to
autosuspend */
-- 
2.17.1

On Thu, Jul 12, 2018 at 01:02:54PM -0400, Lyude Paul
wrote:
> This both uses the legacy modesetting structures in a racy manner, and
> additionally also doesn't even check the right variable (enabled != the
> CRTC is actually turned on for atomic).
> 
> This fixes issues on my P50 regarding the dedicated GPU not entering
> runtime suspend.
> 
> Signed-off-by: Lyude Paul <lyude at redhat.com>
> Cc: stable at vger.kernel.org
On both patch 2&3:

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

->enable vs. ->active is probably the biggest source of pain in atomic,
and beyond typing even more kerneldoc that will be ignored (there's
another series doing exactly that on the list) I have no idea what to do.
90% rule is to look at ->enable in atomic_check code (since DPMS changes
should always work) and ->active in atomic_commit code.

Wrt the legacy state: For the legacy pointers we can set them to NULL for
atomic, and Ville has done that. That's real effective at stopping drivers
from looking at the wrong thing. But for the others like this one here I
dunno what to do to effectively hide them from atomic drivers.

</rant>

Cheers, Daniel
> ---
>  drivers/gpu/drm/nouveau/nouveau_drm.c | 11 -----------
>  1 file changed, 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c
b/drivers/gpu/drm/nouveau/nouveau_drm.c
> index 0f668e275ee1..c7ec86d6c3c9 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
> @@ -881,22 +881,11 @@ nouveau_pmops_runtime_resume(struct device *dev)
>  static int
>  nouveau_pmops_runtime_idle(struct device *dev)
>  {
> -	struct pci_dev *pdev = to_pci_dev(dev);
> -	struct drm_device *drm_dev = pci_get_drvdata(pdev);
> -	struct nouveau_drm *drm = nouveau_drm(drm_dev);
> -	struct drm_crtc *crtc;
> -
>  	if (!nouveau_pmops_runtime()) {
>  		pm_runtime_forbid(dev);
>  		return -EBUSY;
>  	}
>  
> -	list_for_each_entry(crtc, &drm->dev->mode_config.crtc_list,
head) {
> -		if (crtc->enabled) {
> -			DRM_DEBUG_DRIVER("failing to power off - crtc active\n");
> -			return -EBUSY;
> -		}
> -	}
>  	pm_runtime_mark_last_busy(dev);
>  	pm_runtime_autosuspend(dev);
>  	/* we don't want the main rpm_idle to call suspend - we want to
autosuspend */
> -- 
> 2.17.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

On Thu, Jul 12, 2018 at 01:02:53PM -0400, Lyude Paul
wrote:
> --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> @@ -1878,7 +1878,7 @@ nv50_disp_atomic_commit(struct drm_device *dev,
>  		nv50_disp_atomic_commit_tail(state);
>  
>  	drm_for_each_crtc(crtc, dev) {
> -		if (crtc->state->enable) {
> +		if (crtc->state->active) {
>  			if (!drm->have_disp_power_ref) {
>  				drm->have_disp_power_ref = true;
>  				return 0;
Somewhat tangential comment on this older patch, since you
continue to dig around in the runtime PM area:

Whenever a crtc is activated or deactivated in nouveau, we iterate
over all crtcs and acquire a runtime PM if a crtc is active and
previously there was no active one, or we drop a ref if none is
active and previously there was an active one.

For a while now I've been thinking that it would be more straightforward
to acquire a ref whenever a crtc is activated and drop one when a crtc
is deactivated, i.e. hold one ref for every active crtc.  That way the
have_disp_power_ref variable as well as the iteration logic could be
removed, leading to a simplification.  Just a suggestion anyway.

Thanks,

Lukas