Re: [RFC v3 21/21] omap3isp: Don't rely on devm for memory resource management

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

Thank you for the patch.

On Saturday 27 Aug 2016 02:43:29 Sakari Ailus wrote:
> devm functions are fine for managing resources that are directly related
> to the device at hand and that have no other dependencies. However, a
> process holding a file handle to a device created by a driver for a device
> may result in the file handle left behind after the device is long gone.
> This will result in accessing released (and potentially reallocated)
> memory.
> 
> Instead, rely on the media device which will stick around until all users
> are gone.

Could you move this patch to the beginning of the series to show that 
converting the driver away from devm_* isn't enough to fix the problem that 
the series tries to address ?

> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/media/platform/omap3isp/isp.c         | 38 +++++++++++++++++-------
>  drivers/media/platform/omap3isp/ispccp2.c     |  3 ++-
>  drivers/media/platform/omap3isp/isph3a_aewb.c | 20 +++++++++-----
>  drivers/media/platform/omap3isp/isph3a_af.c   | 20 +++++++++-----
>  drivers/media/platform/omap3isp/isphist.c     |  5 ++--
>  drivers/media/platform/omap3isp/ispstat.c     |  2 ++
>  6 files changed, 63 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/media/platform/omap3isp/isp.c
> b/drivers/media/platform/omap3isp/isp.c index 689efe8..262ddf7 100644
> --- a/drivers/media/platform/omap3isp/isp.c
> +++ b/drivers/media/platform/omap3isp/isp.c
> @@ -1370,7 +1370,7 @@ static int isp_get_clocks(struct isp_device *isp)
>  	unsigned int i;
> 
>  	for (i = 0; i < ARRAY_SIZE(isp_clocks); ++i) {
> -		clk = devm_clk_get(isp->dev, isp_clocks[i]);
> +		clk = clk_get(isp->dev, isp_clocks[i]);
>  		if (IS_ERR(clk)) {
>  			dev_err(isp->dev, "clk_get %s failed\n", 
isp_clocks[i]);
>  			return PTR_ERR(clk);
> @@ -1382,6 +1382,14 @@ static int isp_get_clocks(struct isp_device *isp)
>  	return 0;
>  }
> 
> +static void isp_put_clocks(struct isp_device *isp)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(isp_clocks); ++i)
> +		clk_put(isp->clock[i]);
> +}
> +
>  /*
>   * omap3isp_get - Acquire the ISP resource.
>   *
> @@ -1596,7 +1604,6 @@ static void isp_unregister_entities(struct isp_device
> *isp) omap3isp_stat_unregister_entities(&isp->isp_af);
>  	omap3isp_stat_unregister_entities(&isp->isp_hist);
> 
> -	v4l2_device_unregister(&isp->v4l2_dev);

This isn't correct. The v4l2_device instance should be unregistered here, to 
make sure that the subdev nodes are unregistered too. And even if moving the 
function call was correct, it should be done in a separate patch as it's 
unrelated to $SUBJECT.

>  	media_device_unregister(isp->media_dev);
>  	media_device_put(isp->media_dev);
>  }
> @@ -1951,6 +1958,8 @@ static void isp_release(struct media_device *mdev)
>  {
>  	struct isp_device *isp = media_device_priv(mdev);
> 
> +	v4l2_device_unregister(&isp->v4l2_dev);
> +
>  	isp_cleanup_modules(isp);
>  	isp_xclk_cleanup(isp);
> 
> @@ -1959,6 +1968,10 @@ static void isp_release(struct media_device *mdev)
>  	__omap3isp_put(isp, false);
> 
>  	media_entity_enum_cleanup(&isp->crashed);
> +
> +	isp_put_clocks(isp);
> +
> +	kfree(isp);
>  }
> 
>  static int isp_attach_iommu(struct isp_device *isp)
> @@ -2211,7 +2224,7 @@ static int isp_probe(struct platform_device *pdev)
>  	int ret;
>  	int i, m;
> 
> -	isp = devm_kzalloc(&pdev->dev, sizeof(*isp), GFP_KERNEL);
> +	isp = kzalloc(sizeof(*isp), GFP_KERNEL);
>  	if (!isp) {
>  		dev_err(&pdev->dev, "could not allocate memory\n");
>  		return -ENOMEM;
> @@ -2220,21 +2233,23 @@ static int isp_probe(struct platform_device *pdev)
>  	ret = of_property_read_u32(pdev->dev.of_node, "ti,phy-type",
>  				   &isp->phy_type);
>  	if (ret)
> -		return ret;
> +		goto error_release_isp;

I propose reorganizing this a bit more and moving DT parsing after the 
platform_set_drvdata() call. That way you can pass the ISP device to 
isp_of_parse_nodes() (which by the way also calls devm_* functions) and group 
the mutex_destroy() and various kfree() calls under a single error label. You 
might want to split this reorganization in a separate patch.

>  	isp->syscon = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
>  						      "syscon");
> -	if (IS_ERR(isp->syscon))
> -		return PTR_ERR(isp->syscon);
> +	if (IS_ERR(isp->syscon)) {
> +		ret = PTR_ERR(isp->syscon);
> +		goto error_release_isp;
> +	}
> 
>  	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 1,
>  					 &isp->syscon_offset);
>  	if (ret)
> -		return ret;
> +		goto error_release_isp;
> 
>  	ret = isp_of_parse_nodes(&pdev->dev, &isp->notifier);
>  	if (ret < 0)
> -		return ret;
> +		goto error_release_isp;
> 
>  	isp->autoidle = autoidle;
> 
> @@ -2251,8 +2266,8 @@ static int isp_probe(struct platform_device *pdev)
>  	platform_set_drvdata(pdev, isp);
> 
>  	/* Regulators */
> -	isp->isp_csiphy1.vdd = devm_regulator_get(&pdev->dev, "vdd-csiphy1");
> -	isp->isp_csiphy2.vdd = devm_regulator_get(&pdev->dev, "vdd-csiphy2");
> +	isp->isp_csiphy1.vdd = regulator_get(&pdev->dev, "vdd-csiphy1");
> +	isp->isp_csiphy2.vdd = regulator_get(&pdev->dev, "vdd-csiphy2");

How about moving this to omap3isp_csiphy_init() ? You also need to release 
those regulators.

However, I wonder whether we couldn't keep devm_* for the clocks and 
regulators, as they shouldn't be touched anymore after remove() time.

>  	/* Clocks
>  	 *
> @@ -2384,6 +2399,9 @@ error_isp:
>  	__omap3isp_put(isp, false);
>  error:
>  	mutex_destroy(&isp->isp_mutex);
> +	isp_put_clocks(isp);
> +error_release_isp:
> +	kfree(isp);
> 
>  	return ret;
>  }
> diff --git a/drivers/media/platform/omap3isp/ispccp2.c
> b/drivers/media/platform/omap3isp/ispccp2.c index ca09523..d49ce8a 100644
> --- a/drivers/media/platform/omap3isp/ispccp2.c
> +++ b/drivers/media/platform/omap3isp/ispccp2.c
> @@ -1135,7 +1135,7 @@ int omap3isp_ccp2_init(struct isp_device *isp)
>  	 * TODO: Don't hardcode the usage of PHY1 (shared with CSI2c).
>  	 */
>  	if (isp->revision == ISP_REVISION_2_0) {
> -		ccp2->vdds_csib = devm_regulator_get(isp->dev, "vdds_csib");
> +		ccp2->vdds_csib = regulator_get(isp->dev, "vdds_csib");
>  		if (IS_ERR(ccp2->vdds_csib)) {
>  			dev_dbg(isp->dev,
>  				"Could not get regulator vdds_csib\n");
> @@ -1163,4 +1163,5 @@ void omap3isp_ccp2_cleanup(struct isp_device *isp)
> 
>  	omap3isp_video_cleanup(&ccp2->video_in);
>  	media_entity_cleanup(&ccp2->subdev.entity);
> +	regulator_put(ccp2->vdds_csib);
>  }
> diff --git a/drivers/media/platform/omap3isp/isph3a_aewb.c
> b/drivers/media/platform/omap3isp/isph3a_aewb.c index ccaf92f..130df8b
> 100644
> --- a/drivers/media/platform/omap3isp/isph3a_aewb.c
> +++ b/drivers/media/platform/omap3isp/isph3a_aewb.c

Please see my comments on isph3a_af.c below, they apply here too.

[snip]

> diff --git a/drivers/media/platform/omap3isp/isph3a_af.c
> b/drivers/media/platform/omap3isp/isph3a_af.c index 92937f7..7eecf97 100644
> --- a/drivers/media/platform/omap3isp/isph3a_af.c
> +++ b/drivers/media/platform/omap3isp/isph3a_af.c
> @@ -352,9 +352,10 @@ int omap3isp_h3a_af_init(struct isp_device *isp)
>  {
>  	struct ispstat *af = &isp->isp_af;
>  	struct omap3isp_h3a_af_config *af_cfg;
> -	struct omap3isp_h3a_af_config *af_recover_cfg;
> +	struct omap3isp_h3a_af_config *af_recover_cfg = NULL;
> +	int ret;
> 
> -	af_cfg = devm_kzalloc(isp->dev, sizeof(*af_cfg), GFP_KERNEL);
> +	af_cfg = kzalloc(sizeof(*af_cfg), GFP_KERNEL);
>  	if (af_cfg == NULL)
>  		return -ENOMEM;
> 
> @@ -364,12 +365,12 @@ int omap3isp_h3a_af_init(struct isp_device *isp)
>  	af->isp = isp;
> 
>  	/* Set recover state configuration */
> -	af_recover_cfg = devm_kzalloc(isp->dev, sizeof(*af_recover_cfg),
> -				      GFP_KERNEL);
> +	af_recover_cfg = kzalloc(sizeof(*af_recover_cfg), GFP_KERNEL);
>  	if (!af_recover_cfg) {
>  		dev_err(af->isp->dev, "AF: cannot allocate memory for recover 
"
>  				      "configuration.\n");
> -		return -ENOMEM;
> +		ret = -ENOMEM;
> +		goto err;
>  	}
> 
>  	af_recover_cfg->paxel.h_start = OMAP3ISP_AF_PAXEL_HZSTART_MIN;
> @@ -381,13 +382,20 @@ int omap3isp_h3a_af_init(struct isp_device *isp)
>  	if (h3a_af_validate_params(af, af_recover_cfg)) {
>  		dev_err(af->isp->dev, "AF: recover configuration is "
>  				      "invalid.\n");

Unrelated to this patch, but this shouldn't happen. I wonder whether we could 
remove the check.

> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto err;
>  	}
> 
>  	af_recover_cfg->buf_size = h3a_af_get_buf_size(af_recover_cfg);
>  	af->recover_priv = af_recover_cfg;
> 
>  	return omap3isp_stat_init(af, "AF", &h3a_af_subdev_ops);

You need to catch the omap3isp_stat_init() failures too. Something like

	ret = omap3isp_stat_init(af, "AF", &h3a_af_subdev_ops);

done:
	if (ret) {
		kfree(af_recover_cfg);
		kfree(af_cfg);
	}

	return ret;

and replacing the above goto err; with goto done; ?

> +
> +err:
> +	kfree(af_cfg);
> +	kfree(af_recover_cfg);
> +
> +	return ret;
>  }
> 
>  void omap3isp_h3a_af_cleanup(struct isp_device *isp)
> diff --git a/drivers/media/platform/omap3isp/isphist.c
> b/drivers/media/platform/omap3isp/isphist.c index 7138b04..976cab0 100644
> --- a/drivers/media/platform/omap3isp/isphist.c
> +++ b/drivers/media/platform/omap3isp/isphist.c
> @@ -477,9 +477,9 @@ int omap3isp_hist_init(struct isp_device *isp)
>  {
>  	struct ispstat *hist = &isp->isp_hist;
>  	struct omap3isp_hist_config *hist_cfg;
> -	int ret = -1;
> +	int ret;
> 
> -	hist_cfg = devm_kzalloc(isp->dev, sizeof(*hist_cfg), GFP_KERNEL);
> +	hist_cfg = kzalloc(sizeof(*hist_cfg), GFP_KERNEL);
>  	if (hist_cfg == NULL)
>  		return -ENOMEM;

There's a return in the middle of this function that should be turned into a 
goto done.

> @@ -517,6 +517,7 @@ int omap3isp_hist_init(struct isp_device *isp)

With a done label added right here.

>  	if (ret) {
>  		if (hist->dma_ch)
>  			dma_release_channel(hist->dma_ch);
> +		kfree(hist_cfg);
>  	}
> 
>  	return ret;
> diff --git a/drivers/media/platform/omap3isp/ispstat.c
> b/drivers/media/platform/omap3isp/ispstat.c index 1b9217d..1c1365f 100644
> --- a/drivers/media/platform/omap3isp/ispstat.c
> +++ b/drivers/media/platform/omap3isp/ispstat.c
> @@ -1059,4 +1059,6 @@ void omap3isp_stat_cleanup(struct ispstat *stat)
>  	mutex_destroy(&stat->ioctl_lock);
>  	isp_stat_bufs_free(stat);
>  	kfree(stat->buf);
> +	kfree(stat->priv);
> +	kfree(stat->recover_priv);
>  }

-- 
Regards,

Laurent Pinchart