[PATCH v2] media: hi846: fix usage of pm_runtime_get_if_in_use()

[PATCH v2] media: hi846: fix usage of pm_runtime_get_if_in_use()

[Martin Kepplinger]

pm_runtime_get_if_in_use() does not only return nonzero values when
the device is in use, it can return a negative errno too.

And especially during resuming from system suspend, when runtime pm
is not yet up again, -EAGAIN is being returned, so the subsequent
pm_runtime_put() call results in a refcount underflow.

Fix system-resume by handling -EAGAIN of pm_runtime_get_if_in_use().

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
---

revision history
----------------
v2 (thank you Sakari and Laurent):
* drop the other patch (the streaming-state in suspend/resume needs to
  be solved differently).
* Sakari pointed out that many drivers are affected by this and that
  runtime-pm might need changes instead. I think this patch doesn't hurt
  and could serve as a reminder to do so.

v1: initial submission:
https://lore.kernel.org/linux-media/20230405092904.1129395-1-martin.kepplinger@puri.sm/

 drivers/media/i2c/hi846.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/hi846.c b/drivers/media/i2c/hi846.c
index 306dc35e925f..f8709cdf28b3 100644
--- a/drivers/media/i2c/hi846.c
+++ b/drivers/media/i2c/hi846.c
@@ -1353,7 +1353,8 @@ static int hi846_set_ctrl(struct v4l2_ctrl *ctrl)
 					 exposure_max);
 	}
 
-	if (!pm_runtime_get_if_in_use(&client->dev))
+	ret = pm_runtime_get_if_in_use(&client->dev);
+	if (!ret || ret == -EAGAIN)
 		return 0;
 
 	switch (ctrl->id) {
-- 
2.30.2

Re: [PATCH v2] media: hi846: fix usage of pm_runtime_get_if_in_use()

[Sakari Ailus]

Hi Martin,

On Tue, Apr 25, 2023 at 11:47:47AM +0200, Martin Kepplinger wrote:
> pm_runtime_get_if_in_use() does not only return nonzero values when
> the device is in use, it can return a negative errno too.
> 
> And especially during resuming from system suspend, when runtime pm
> is not yet up again, -EAGAIN is being returned, so the subsequent
> pm_runtime_put() call results in a refcount underflow.
> 
> Fix system-resume by handling -EAGAIN of pm_runtime_get_if_in_use().
> 
> Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
> ---
> 
> revision history
> ----------------
> v2 (thank you Sakari and Laurent):
> * drop the other patch (the streaming-state in suspend/resume needs to
>   be solved differently).
> * Sakari pointed out that many drivers are affected by this and that
>   runtime-pm might need changes instead. I think this patch doesn't hurt
>   and could serve as a reminder to do so.

I guess it's appropriate to add:

Fixes: e8c0882685f9 ("media: i2c: add driver for the SK Hynix Hi-846 8M pixel camera")

-- 
Sakari Ailus

Re: [PATCH v2] media: hi846: fix usage of pm_runtime_get_if_in_use()

[Martin Kepplinger]

Am Dienstag, dem 16.05.2023 um 16:22 +0300 schrieb Sakari Ailus:
> Hi Martin,
> 
> On Tue, Apr 25, 2023 at 11:47:47AM +0200, Martin Kepplinger wrote:
> > pm_runtime_get_if_in_use() does not only return nonzero values when
> > the device is in use, it can return a negative errno too.
> > 
> > And especially during resuming from system suspend, when runtime pm
> > is not yet up again, -EAGAIN is being returned, so the subsequent
> > pm_runtime_put() call results in a refcount underflow.
> > 
> > Fix system-resume by handling -EAGAIN of
> > pm_runtime_get_if_in_use().
> > 
> > Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
> > ---
> > 
> > revision history
> > ----------------
> > v2 (thank you Sakari and Laurent):
> > * drop the other patch (the streaming-state in suspend/resume needs
> > to
> >   be solved differently).
> > * Sakari pointed out that many drivers are affected by this and
> > that
> >   runtime-pm might need changes instead. I think this patch doesn't
> > hurt
> >   and could serve as a reminder to do so.
> 
> I guess it's appropriate to add:
> 
> Fixes: e8c0882685f9 ("media: i2c: add driver for the SK Hynix Hi-846
> 8M pixel camera")
> 

I agree. Feel free to do so when applying.

                            martin

Re: [PATCH v2] media: hi846: fix usage of pm_runtime_get_if_in_use()

[Sakari Ailus]

On Tue, May 23, 2023 at 12:07:54PM +0200, Martin Kepplinger wrote:
> Am Dienstag, dem 16.05.2023 um 16:22 +0300 schrieb Sakari Ailus:
> > Hi Martin,
> > 
> > On Tue, Apr 25, 2023 at 11:47:47AM +0200, Martin Kepplinger wrote:
> > > pm_runtime_get_if_in_use() does not only return nonzero values when
> > > the device is in use, it can return a negative errno too.
> > > 
> > > And especially during resuming from system suspend, when runtime pm
> > > is not yet up again, -EAGAIN is being returned, so the subsequent
> > > pm_runtime_put() call results in a refcount underflow.
> > > 
> > > Fix system-resume by handling -EAGAIN of
> > > pm_runtime_get_if_in_use().
> > > 
> > > Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
> > > ---
> > > 
> > > revision history
> > > ----------------
> > > v2 (thank you Sakari and Laurent):
> > > * drop the other patch (the streaming-state in suspend/resume needs
> > > to
> > >   be solved differently).
> > > * Sakari pointed out that many drivers are affected by this and
> > > that
> > >   runtime-pm might need changes instead. I think this patch doesn't
> > > hurt
> > >   and could serve as a reminder to do so.
> > 
> > I guess it's appropriate to add:
> > 
> > Fixes: e8c0882685f9 ("media: i2c: add driver for the SK Hynix Hi-846
> > 8M pixel camera")
> > 
> 
> I agree. Feel free to do so when applying.

Done!

-- 
Sakari Ailus