[PATCH] drm/bochs: Drop manual put on probe error path

[PATCH] drm/bochs: Drop manual put on probe error path

[Myeonghun Pak]

bochs_pci_probe() allocates the DRM device with devm_drm_dev_alloc(),
which registers a devres action to drop the initial DRM device reference
on driver detach or probe failure.

The error path currently calls drm_dev_put() manually. If probe then
returns an error, devres will run the registered release action and put
the same device again, after the first put may already have released it.

Return the probe error directly and let devres own the final put.

Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
---
 drivers/gpu/drm/tiny/bochs.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
index 222e4ae1ab..5d8dc5efec 100644
--- a/drivers/gpu/drm/tiny/bochs.c
+++ b/drivers/gpu/drm/tiny/bochs.c
@@ -761,25 +761,21 @@ static int bochs_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent
 
 	ret = pcim_enable_device(pdev);
 	if (ret)
-		goto err_free_dev;
+		return ret;
 
 	pci_set_drvdata(pdev, dev);
 
 	ret = bochs_load(bochs);
 	if (ret)
-		goto err_free_dev;
+		return ret;
 
 	ret = drm_dev_register(dev, 0);
 	if (ret)
-		goto err_free_dev;
+		return ret;
 
 	drm_client_setup(dev, NULL);
 
 	return ret;
-
-err_free_dev:
-	drm_dev_put(dev);
-	return ret;
 }
 
 static void bochs_pci_remove(struct pci_dev *pdev)
-- 
2.39.5

Re: [PATCH] drm/bochs: Drop manual put on probe error path

[Thomas Zimmermann]

Hi,

please add fixes tags to all these patches you're sending. You also need 
to CC stable so that they can be backported easily. Also list the AI 
you're using to find and create these patches.

Best regards
Thomas

Am 24.04.26 um 14:34 schrieb Myeonghun Pak:
> bochs_pci_probe() allocates the DRM device with devm_drm_dev_alloc(),
> which registers a devres action to drop the initial DRM device reference
> on driver detach or probe failure.
>
> The error path currently calls drm_dev_put() manually. If probe then
> returns an error, devres will run the registered release action and put
> the same device again, after the first put may already have released it.
>
> Return the probe error directly and let devres own the final put.
>
> Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
> ---
>   drivers/gpu/drm/tiny/bochs.c | 10 +++-------
>   1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
> index 222e4ae1ab..5d8dc5efec 100644
> --- a/drivers/gpu/drm/tiny/bochs.c
> +++ b/drivers/gpu/drm/tiny/bochs.c
> @@ -761,25 +761,21 @@ static int bochs_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent
>   
>   	ret = pcim_enable_device(pdev);
>   	if (ret)
> -		goto err_free_dev;
> +		return ret;
>   
>   	pci_set_drvdata(pdev, dev);
>   
>   	ret = bochs_load(bochs);
>   	if (ret)
> -		goto err_free_dev;
> +		return ret;
>   
>   	ret = drm_dev_register(dev, 0);
>   	if (ret)
> -		goto err_free_dev;
> +		return ret;
>   
>   	drm_client_setup(dev, NULL);
>   
>   	return ret;
> -
> -err_free_dev:
> -	drm_dev_put(dev);
> -	return ret;
>   }
>   
>   static void bochs_pci_remove(struct pci_dev *pdev)

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)

Re: [PATCH] drm/bochs: Drop manual put on probe error path

[Thomas Zimmermann]

Hi

Am 24.04.26 um 15:40 schrieb Myeonghun Pak:
> Hi Thomas,
>
> Thank you for your reply. I will ensure that the requested |Fixes| tag 
> and |stable| CC are included in the next patch I send.
>
> Regarding your request for information about AI usage and how the 
> issue was identified:
>
>   * This issue was identified during our ongoing static-analysis
>     research while reviewing kernel code.
>     1
>     <https://mail.google.com/mail/u/0/#all/%23thread-f:1863355320119932959>
>   * Specifically, it was found by an experimental static analysis tool
>     that we are currently developing. The tool is not public yet, so I
>     prefer not to disclose further project details at this stage.
>
>   * AI was used only for cross-review, not as the primary means of
>     finding or fixing the bug.
>   * I manually reviewed the code and verified the issue before sending
>     the patch.
>
> I will incorporate your requests and this additional context, and then 
> resend the modified patch.

Thanks a lot.

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>

Best regards
Thomas

>
> Thank you.
>
> Myeonghun Pak
>
>
> 2026년 4월 24일 (금) 오후 10:25, Thomas Zimmermann 
> <tzimmermann@suse.de>님이 작성:
>
>     Hi,
>
>     please add fixes tags to all these patches you're sending. You
>     also need
>     to CC stable so that they can be backported easily. Also list the AI
>     you're using to find and create these patches.
>
>     Best regards
>     Thomas
>
>     Am 24.04.26 um 14:34 schrieb Myeonghun Pak:
>     > bochs_pci_probe() allocates the DRM device with
>     devm_drm_dev_alloc(),
>     > which registers a devres action to drop the initial DRM device
>     reference
>     > on driver detach or probe failure.
>     >
>     > The error path currently calls drm_dev_put() manually. If probe then
>     > returns an error, devres will run the registered release action
>     and put
>     > the same device again, after the first put may already have
>     released it.
>     >
>     > Return the probe error directly and let devres own the final put.
>     >
>     > Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
>     > ---
>     >   drivers/gpu/drm/tiny/bochs.c | 10 +++-------
>     >   1 file changed, 3 insertions(+), 7 deletions(-)
>     >
>     > diff --git a/drivers/gpu/drm/tiny/bochs.c
>     b/drivers/gpu/drm/tiny/bochs.c
>     > index 222e4ae1ab..5d8dc5efec 100644
>     > --- a/drivers/gpu/drm/tiny/bochs.c
>     > +++ b/drivers/gpu/drm/tiny/bochs.c
>     > @@ -761,25 +761,21 @@ static int bochs_pci_probe(struct pci_dev
>     *pdev, const struct pci_device_id *ent
>     >
>     >       ret = pcim_enable_device(pdev);
>     >       if (ret)
>     > -             goto err_free_dev;
>     > +             return ret;
>     >
>     >       pci_set_drvdata(pdev, dev);
>     >
>     >       ret = bochs_load(bochs);
>     >       if (ret)
>     > -             goto err_free_dev;
>     > +             return ret;
>     >
>     >       ret = drm_dev_register(dev, 0);
>     >       if (ret)
>     > -             goto err_free_dev;
>     > +             return ret;
>     >
>     >       drm_client_setup(dev, NULL);
>     >
>     >       return ret;
>     > -
>     > -err_free_dev:
>     > -     drm_dev_put(dev);
>     > -     return ret;
>     >   }
>     >
>     >   static void bochs_pci_remove(struct pci_dev *pdev)
>
>     -- 
>     --
>     Thomas Zimmermann
>     Graphics Driver Developer
>     SUSE Software Solutions Germany GmbH
>     Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
>     <http://www.suse.com>
>     GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG
>     Nürnberg)
>
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)

Re: [PATCH] drm/bochs: Drop manual put on probe error path

[Thomas Zimmermann]

Hi

Am 30.04.26 um 15:52 schrieb Myeonghun Pak:
> Thanks for the explanation.
>
> I see your point now. My patch treated uart_add_one_port() failure as 
> a fatal
> probe failure, but the current code is intentionally trying to keep 
> the driver
> alive so that other MAX3100 ports can still be available even if one 
> port cannot
> be instantiated.
>
> Please drop this patch. I will not pursue this direction.

Why? The was patch was good AFAICT. It's just missing a Fixes tag.

Best regards
Thomas

>
> Thanks,
> Myeonghun
>
> 2026년 4월 24일 (금) 오후 11:59, Thomas Zimmermann 
> <tzimmermann@suse.de>님이 작성:
>
>     Hi
>
>     Am 24.04.26 um 15:40 schrieb Myeonghun Pak:
>     > Hi Thomas,
>     >
>     > Thank you for your reply. I will ensure that the requested
>     |Fixes| tag
>     > and |stable| CC are included in the next patch I send.
>     >
>     > Regarding your request for information about AI usage and how the
>     > issue was identified:
>     >
>     >   * This issue was identified during our ongoing static-analysis
>     >     research while reviewing kernel code.
>     >     1
>     >   
>      <https://mail.google.com/mail/u/0/#all/%23thread-f:1863355320119932959>
>     >   * Specifically, it was found by an experimental static
>     analysis tool
>     >     that we are currently developing. The tool is not public
>     yet, so I
>     >     prefer not to disclose further project details at this stage.
>     >
>     >   * AI was used only for cross-review, not as the primary means of
>     >     finding or fixing the bug.
>     >   * I manually reviewed the code and verified the issue before
>     sending
>     >     the patch.
>     >
>     > I will incorporate your requests and this additional context,
>     and then
>     > resend the modified patch.
>
>     Thanks a lot.
>
>     Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
>
>     Best regards
>     Thomas
>
>     >
>     > Thank you.
>     >
>     > Myeonghun Pak
>     >
>     >
>     > 2026년 4월 24일 (금) 오후 10:25, Thomas Zimmermann
>     > <tzimmermann@suse.de>님이 작성:
>     >
>     >     Hi,
>     >
>     >     please add fixes tags to all these patches you're sending. You
>     >     also need
>     >     to CC stable so that they can be backported easily. Also
>     list the AI
>     >     you're using to find and create these patches.
>     >
>     >     Best regards
>     >     Thomas
>     >
>     >     Am 24.04.26 um 14:34 schrieb Myeonghun Pak:
>     >     > bochs_pci_probe() allocates the DRM device with
>     >     devm_drm_dev_alloc(),
>     >     > which registers a devres action to drop the initial DRM device
>     >     reference
>     >     > on driver detach or probe failure.
>     >     >
>     >     > The error path currently calls drm_dev_put() manually. If
>     probe then
>     >     > returns an error, devres will run the registered release
>     action
>     >     and put
>     >     > the same device again, after the first put may already have
>     >     released it.
>     >     >
>     >     > Return the probe error directly and let devres own the
>     final put.
>     >     >
>     >     > Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
>     >     > ---
>     >     >   drivers/gpu/drm/tiny/bochs.c | 10 +++-------
>     >     >   1 file changed, 3 insertions(+), 7 deletions(-)
>     >     >
>     >     > diff --git a/drivers/gpu/drm/tiny/bochs.c
>     >     b/drivers/gpu/drm/tiny/bochs.c
>     >     > index 222e4ae1ab..5d8dc5efec 100644
>     >     > --- a/drivers/gpu/drm/tiny/bochs.c
>     >     > +++ b/drivers/gpu/drm/tiny/bochs.c
>     >     > @@ -761,25 +761,21 @@ static int bochs_pci_probe(struct
>     pci_dev
>     >     *pdev, const struct pci_device_id *ent
>     >     >
>     >     >       ret = pcim_enable_device(pdev);
>     >     >       if (ret)
>     >     > -             goto err_free_dev;
>     >     > +             return ret;
>     >     >
>     >     >       pci_set_drvdata(pdev, dev);
>     >     >
>     >     >       ret = bochs_load(bochs);
>     >     >       if (ret)
>     >     > -             goto err_free_dev;
>     >     > +             return ret;
>     >     >
>     >     >       ret = drm_dev_register(dev, 0);
>     >     >       if (ret)
>     >     > -             goto err_free_dev;
>     >     > +             return ret;
>     >     >
>     >     >       drm_client_setup(dev, NULL);
>     >     >
>     >     >       return ret;
>     >     > -
>     >     > -err_free_dev:
>     >     > -     drm_dev_put(dev);
>     >     > -     return ret;
>     >     >   }
>     >     >
>     >     >   static void bochs_pci_remove(struct pci_dev *pdev)
>     >
>     >     --
>     >     --
>     >     Thomas Zimmermann
>     >     Graphics Driver Developer
>     >     SUSE Software Solutions Germany GmbH
>     >     Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
>     <http://www.suse.com>
>     >     <http://www.suse.com>
>     >     GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB
>     36809, AG
>     >     Nürnberg)
>     >
>     >
>
>     -- 
>     --
>     Thomas Zimmermann
>     Graphics Driver Developer
>     SUSE Software Solutions Germany GmbH
>     Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
>     <http://www.suse.com>
>     GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG
>     Nürnberg)
>
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)

Re: [PATCH] drm/bochs: Drop manual put on probe error path

[Thomas Zimmermann]

Am 24.04.26 um 14:34 schrieb Myeonghun Pak:
> bochs_pci_probe() allocates the DRM device with devm_drm_dev_alloc(),
> which registers a devres action to drop the initial DRM device reference
> on driver detach or probe failure.
>
> The error path currently calls drm_dev_put() manually. If probe then
> returns an error, devres will run the registered release action and put
> the same device again, after the first put may already have released it.
>
> Return the probe error directly and let devres own the final put.
>
> Signed-off-by: Myeonghun Pak <mhun512@gmail.com>

Fixes: 04826f588682 ("drm/bochs: Allocate DRM device in struct 
bochs_device")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: virtualization@lists.linux.dev
Cc: <stable@vger.kernel.org> # v6.13+


> ---
>   drivers/gpu/drm/tiny/bochs.c | 10 +++-------
>   1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
> index 222e4ae1ab..5d8dc5efec 100644
> --- a/drivers/gpu/drm/tiny/bochs.c
> +++ b/drivers/gpu/drm/tiny/bochs.c
> @@ -761,25 +761,21 @@ static int bochs_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent
>   
>   	ret = pcim_enable_device(pdev);
>   	if (ret)
> -		goto err_free_dev;
> +		return ret;
>   
>   	pci_set_drvdata(pdev, dev);
>   
>   	ret = bochs_load(bochs);
>   	if (ret)
> -		goto err_free_dev;
> +		return ret;
>   
>   	ret = drm_dev_register(dev, 0);
>   	if (ret)
> -		goto err_free_dev;
> +		return ret;
>   
>   	drm_client_setup(dev, NULL);
>   
>   	return ret;
> -
> -err_free_dev:
> -	drm_dev_put(dev);
> -	return ret;
>   }
>   
>   static void bochs_pci_remove(struct pci_dev *pdev)

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)

Re: drm/bochs: Drop manual put on probe error path

[Markus Elfring]

…
> > Return the probe error directly and let devres own the final put.
…
> Fixes: 04826f588682 ("drm/bochs: Allocate DRM device in struct 
> bochs_device")
…

See also once more:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v7.1-rc2#n145

Regards,
Markus

[PATCH] drm/bochs: Drop manual put on probe error path

[Myeonghun Pak]

bochs_pci_probe() allocates the DRM device with devm_drm_dev_alloc(),
which registers a devres action to drop the initial DRM device reference
on driver detach or probe failure.

The error path currently calls drm_dev_put() manually. If probe then
returns an error, devres will run the registered release action and put
the same device again, after the first put may already have released it.

Return the probe error directly and let devres own the final put.

Fixes: 04826f588682 ("drm/bochs: Allocate DRM device in struct bochs_device")
Cc: stable@vger.kernel.org
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
---
 drivers/gpu/drm/tiny/bochs.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
index 222e4ae1ab..5d8dc5efec 100644
--- a/drivers/gpu/drm/tiny/bochs.c
+++ b/drivers/gpu/drm/tiny/bochs.c
@@ -761,25 +761,21 @@ static int bochs_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent
 
 	ret = pcim_enable_device(pdev);
 	if (ret)
-		goto err_free_dev;
+		return ret;
 
 	pci_set_drvdata(pdev, dev);
 
 	ret = bochs_load(bochs);
 	if (ret)
-		goto err_free_dev;
+		return ret;
 
 	ret = drm_dev_register(dev, 0);
 	if (ret)
-		goto err_free_dev;
+		return ret;
 
 	drm_client_setup(dev, NULL);
 
 	return ret;
-
-err_free_dev:
-	drm_dev_put(dev);
-	return ret;
 }
 
 static void bochs_pci_remove(struct pci_dev *pdev)
-- 
2.39.5